Synthesis and thermodynamic properties of nano magnesium borate MgBO 2 (OH) with three different morphologies

Synthesis and thermodynamic properties of nano magnesium borate MgBO 2 (OH) with three different morphologies | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Synthesis and thermodynamic properties of nano magnesium borate MgBO 2 (OH) with three different morphologies Jingxin Bi, Xiaoqin Feng, Jia Zheng, Fanglong Cen, Hongyan Zhang, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4137398/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract MgBO 2 (OH) with flower-like, sea urchin-like, and rice panicle-like morphologies have been synthesized and characterized by XRD, FI-IR, SEM and TEM. The molar enthalpies of solution of MgBO 2 (OH) with different morphologies in 3.00 mol·L − 1 HCl(aq) were measured. With the incorporation of the previously determined enthalpy of solution of H 3 BO 3 in 3.00 mol·L − 1 HCl(aq), the enthalpy of solution of MgO in (HCl + H 3 BO 3 )(aq) and the standard molar enthalpies of formation of MgO(s), H 3 BO 3 (s) and H 2 O(l), the standard molar enthalpies of formation of MgBO 2 (OH) with flower-like, sea urchin-like, and rice panicle-like morphologies were calculated to be -(1465.40 ± 1.44), -(1464.32 ± 1.31) and − (1476.62 ± 1.46) kJ·mol − 1 , respectively. The results show that the morphology and crystal structure of the sample have an effect on its standard molar enthalpy of formation, and the crystal structure has a greater influence. Magnesium borate Different morphologies Standard molar enthalpy of formation Solution calorimetry Figures Figure 1 Figure 2 Figure 3 Figure 4 1 Introduction Borate have been used widely in various materials due to its physical and chemical properties such as flame retardant, heat resistance, high hardness, high strength, wear resistance and light weight[ 1 ]. Among them, magnesium borate was mainly used in luminous materials, flame retardant materials, coatings and other materials due to its high stability, chemical stability and low cost[ 2 – 5 ]. The results show that the morphology and particle size of the sample has a great influence on its properties. For example, the flame retardancy of nano α-4CaO·5B 2 O 3 ·7H 2 O with spherical-like, pupal-like, and sheet-like morphology is enhanced sequentially[ 6 ]; the flame-retardant properties of BaO·4B 2 O 3 ·5H 2 O nanoribbons and nanosheets increases sequentially[ 7 ]; the flame retardancy of 2MgO·B 2 O 3 ·1.5H 2 O with nanowire morphology is superior to that of sample with nanorod morphology[ 8 ]; among zinc borate (Zn 8 [(BO 3 ) 3 O 2 (OH) 3 ]:Eu 3+ ) phosphors with six different morphologies, zinc borate phosphors with hexahedral morphologies exhibit the strongest luminescence intensity[ 9 ]. Therefore, the synthesis and properties research of borate with different morphologies and particle sizes have received increasing attention. MgBO 2 (OH)(2MgO·B 2 O 3 ·H 2 O) is a kind of translucent mineral widely distributed in nature. MgBO 2 (OH) with different morphologies and particle sizes has been prepared using hydrothermal and ion thermal methods, and its properties have been studied. For example, Liu et al.[ 10 ] obtained nanospherical-like MgBO 2 (OH):Eu 3+ , Y 3+ with good luminescent properties by hydrothermal method, indicating that MgBO 2 (OH) is a good luminescent material matrix. Sun[ 11 ] and Liu et al.[ 12 ] synthesized hierarchical porous MgBO 2 (OH) microspheres by hydrothermal method, and the results showed that this sample has potential application prospects as an efficient adsorbent for removing Congo red (CR) or other organic dyes from wastewater. Zhang et al.[ 13 ] prepared porous MgBO 2 (OH) nanospheres by ionic thermal method, which have potential advantages in dye adsorption and heterogeneous catalysis. The above results indicate that MgBO 2 (OH) has good properties in luminescence, mechanics, adsorption and other aspects. Thermodynamic properties can provide information about the stability and reactivity of the substances, playing a very important role in scientific research and industrial production. In the past few decades, researchers have carried out many studies on the thermodynamic properties of borates using calorimetry. For example, Konings R.J.M et al.[ 14 ] measured the standard molar enthalpies of formation of CsBO 2 ; Wang et al.[ 15 ] determined the standard molar formation enthalpies of BaB 8 O 11 (OH) 4 ·3H 2 O and MB 8 O 11 (OH) 4 ·xH 2 O (M = Ca, Sr, Ba); Liang et al.[ 16 ] determined the standard molar enthalpies of formation of 2ZnO·2B 2 O 3 ·3H 2 O and ZnB 4 O 7 ; the standard molar enthalpies of formation of alkali metal and alkaline earth metal hydrated borates such as lithium borate[ 17 ], sodium borate[ 19 ], potassium borate[ 19 , 22 ], calcium borate[ 18 , 23 , 24 ], barium borate[ 25 ] and strontium borate[ 26 ] were tested by Gao[ 17 – 20 ] and Liu et al.[ 6 , 21 ]. At present, a few studies on the thermodynamic properties of hydrated magnesium borate have been reported, such as MgO·3B 2 O 3 ·3.5H 2 O[ 27 ], 2MgO·3B 2 O 3 ·17H 2 O[ 28 ] and 2MgO·B 2 O 3 ·1.5H 2 O[ 29 ]. Research has shown that the thermodynamic properties of materials are related to their morphology and particle size. For example, Liu et al.[ 30 ] found that the standard molar formation enthalpy of formation of nano Ca[B 6 O 9 (OH) 2 ]·3H 2 O with sheet-like, ellipsoidal-like and flower-like morphologies decreased(more exothermic enthalpy) sequentially; Geng et al.[ 31 ] found that the standard molar enthalpy of 2CaO·B 2 O 3 ·H 2 O increases(less exothermic enthalpy) with the decrease of its particle size; Guo et al.[ 32 ] found that the standard molar formation enthalpy of Zn 3 B 10 O 18 ·14H 2 O increases (less exothermic enthalpy) with the decrease of its particle size. Zhu et al.[ 33 ] determined the thermodynamic properties of MgBO 2 (OH) nanowhiskers, but there have been no comparative studies on the thermodynamic properties of MgBO 2 (OH) with different morphologies. In this paper, the MgBO 2 (OH) with three different morphologies were prepared by hydrothermal method, and the standard molar enthalpies of formation of MgBO 2 (OH) with different morphologies were measured, and the influence of morphologies on their thermodynamic properties was analyzed. 2 Experimental 2.1 Synthesis of samples All the chemical reagents used in the experiment were analytical grade. Typically, 1.529 g of MgCl 2 ·6H 2 O, 0.928 g of H 3 BO 3 and 0.300 g of NaOH (molar ratio of Mg:B:OH = 1:2:1) were individually dissolved into 10.0, 30.0 and 10.0 mL of deionized (DI) water. Subsequently, the solutions of H 3 BO 3 and NaOH were successively dropwise added to the above MgCl 2 ·6H 2 O solution under vigorous magnetic stirring, and 0.1g sodium dodecyl sulfonate was added to the MgCl 2 ·6H 2 O solution. Having been agitated for 10 min, the as-formed precursor slurry was transferred into a Teflon-lined stainless steel autoclave, and maintained at 180°C for 12 h. Finally, the obtained white precipitate were collected by filtration and washed with distilled water and ethanol for several times. The flower-like MgBO 2 (OH) named A1 was obtained after drying at 70°C for 12 h. 5.12 g Mg(NO 3 ) 2 ·6H 2 O and 4.34 g NH 4 B 5 O 8 ·4H 2 O were dissolved in 50 mL of distilled water. Then the resulting solution was transferred into the Teflon-lined autoclave after stirring for 10 min and maintained at 160°C for 12 h. After the reaction was completed, the product was cooled to room temperature, filtered, washed with deionized water and anhydrous ethanol for several times. The sea urchin-like microstructure MgBO 2 (OH) named A2 was obtained after drying at 60°C for 12 h. 1.6 g NaOH, 3.66 g H 3 BO 3 and 4.06 g MgCl 2 ·6H 2 O dissolve in 10.0 mL, 30.0 mL and 10.0mL distilled water, respectively. Then the resulting solution was transferred into the Teflon-lined autoclave after stirring for 10 min and maintained at 220°C for 6 h. After the reaction was completed, the product was cooled to room temperature, filtered, washed with deionized water and anhydrous ethanol for several times. The rice panicle-like microstructure MgBO 2 (OH) named A3 was obtained after drying at 60°C for 6 h. 2.2 Characterization of the samples At 298 ± 1K and 0.1 ± 0.01MPa, the phase composition and crystallinity of the products are characterized by X-ray powder diffraction (XRD, Ultima Ⅳ, Cu target), and Fourier infrared spectrometer (FI-IR, Nicolet NEXUS 670) were used to characterize the phase of the samples. The morphologies and sizes of the samples were investigated by scanning electron microscopy (SEM, Nova Nano 450) and transmission electron microscopy(TEM, JEOL JEM-F 200). 2.3Calorimetric experiment MgBO 2 (OH) can be regarded as the products of the following reactions, respectively: MgO(s) + H 3 BO 3 (aq) = MgBO 2 (OH)(s) + H 2 O(l) The thermodynamic cycle designed for the determination of the standard molar enthalpy of formation of MgBO 2 (OH) is shown in Fig. 1 . The 3.00 mol·L − 1 HCl(aq) solvent can dissolve all components of virtual reaction (5), and its concentration is (3.0093 ± 0.0001) mol·L − 1 determined by titration with standard sodium carbonate. Using its density of 1.019 g·cm − 3 (taken from the Handbook of Chemistry), its concentration can also be expressed as the form of HCl·17.575H 2 O[ 34 ]. The molar enthalpies of solution of H 3 BO 3 (s), MgO(s) in 3 mol·L − 1 HCl(aq) were measured, namely Δ r H m θ (1), Δ r H m θ (4), respectively. The calculated amount of MgO(s) was dissolved in (hydrochloric acid + boric acid) aqueous solution which consisted of 3 mol·L − 1 HCl(aq) and the calculated amount of H 3 BO 3 (s) (Δ r H m θ (2)). In all these determinations, strict control of the stoichiometry in each step of the calorimetric cycle must be observed, with the objective that the dissolution of the reactants give the same composition as those of the products in reactions. The standard molar enthalpy of dissolution of MgBO 2 (OH) in 3.0093 mol·dm − 3 HCl(aq) was determined by an application calorimeter at 298.15 K. Applying Hess’s law, the enthalpy of reaction (5) (Δ r H m θ (5)) can be calculated according to the following expression: Δ r H m θ (5)=Δ r H m θ (1)+Δ r H m θ (2)-Δ r H m θ (3)-Δ r H m θ (4) where Δ r H m θ (3) is the enthalpy of dilution of HCl(aq). The standard molar enthalpy of formation of MgBO 2 (OH) can be obtained by combining the standard molar enthalpy of formation of MgO(s), H 3 BO 3 (s) and H 2 O(l) in the virtual reaction. All the enthalpies of solution were measured with an SRC 100 heat conduction microcalorimeter (Wuhan Machinery Technology Co. China), which has been described in detail previously[ 35 ]. To check the performance of the calorimeter, the enthalpy of dissolution of KCl (mass fraction ≥ 0.9999) in 100 mL deionized water at T = 298.15K was determined to be (17.564 ± 0.026) kJ·mol − 1 (Table.1) and the enthalpy of solution of Tris (hydroxymethyl)aminoethane) (mass fraction ≥ 0. 9999) in 100 mL HCl(aq) (0.100 ± 0.0001) mol·L − 1 at T = 298.15K was determined to be (-29.677 ± 0.045) kJ·mol − 1 (Table.2) which are consistent with the results of the measurements reported in the literature[ 36 , 37 ]. The results shows that the device used for measuring the enthalpy of the solution in this work is reliable. Table 1 The enthalpy of solution of KCl in water at 298.15 K. No m /g Δ sol H m /kJ·mol − 1 1 0.3722 17.597 2 0.3704 17.576 3 0.3715 17.526 4 0.3749 17.545 5 0.3752 17.580 Mean 17.564 ± 0.026 Table 2 The enthalpy of solution of Tris in (0.100 ± 0.0001) mol·dm − 3 HCl at 298.15 K No m /g Δ sol H m /kJ·mol − 1 1 0.5000 -29.667 2 0.5003 -29.621 3 0.5000 -29.687 4 0.5003 -29.758 5 0.5007 -29.655 Mean -29.677 ± 0.045 3 Results and discussion 3.1 Characterization of the synthetic sample Figure 2 gives the XRD patterns of the prepared samples A1, A2 and A3. It can be seen from the figure that all diffraction peaks of samples A1, A2 and A3 are basically consistent with the standard card (JCPDS:039-1370), and no other impurity phase exists. Samples A1, A2 and A3 can be considered to be MgBO 2 (OH). The FT-IR spectra of sample A1, A2 and A3 are shown in Fig. 3 a, b, c, respectively. The FT-IR spectrum of synthetic samples exhibit the following absorption bands and they were assigned referring to literature[ 38 ]. The peak shape and peak position of the three samples are consistent. In Fig. 3 , the band at 3290–3580 cm − 1 is the stretching of O-H bond. The band at 1627 cm − 1 is assigned to the H-O-H bending mode, which shows this compound contains crystal water. The bands at 1450cm − 1 , 1396 cm − 1 and 923 cm − 1 are the asymmetric and symmetric stretching modes of B (3) -O, respectively. The band at 1280 cm − 1 and 1174 cm − 1 are in-plane bending of B-O-H. The band at 1068 cm − 1 , 1006cm − 1 and 785 cm − 1 are the asymmetric and symmetric stretching modes of B (4) -O, respectively. The band at 620–713 cm − 1 is the out-of-plane bending of B (3) -O. The band at 557 cm − 1 is the bending of B (3) -O. The low-magnification, high-magnification SEM images, TEM images and SAED images of three samples with different morphologies are shown in Fig. 4 . From Fig. 4 (a-d), it can be observed that sample A1 exhibits the flower-like microstructure, which is assembled by nanosheets with an average length of 500 nm, a width of 500 nm and thickness of about 10 nm. As shown in Fig. 4 (e-h), sample A2 exhibits the sea urchin-like microstructure, which is constructed by a large number of nanowires with an average length of 500 nm and diameter of 10 nm. From Fig. 4 (i-l), it can be seen that sample A3 exhibits the rice panicle-like microstructure, which is composed of nanorods with an average length of 100 nm and diameter of 20 nm. It can be found from SAED images (Fig. 4 . d, h, l(inset)) that the samples A1 and A2 are polycrystalline structure, while A3 is monocrystalline structure. 3.2 Results of the calorimetric experiment The molar enthalpies of solution of MgBO 2 (OH) with different morphologies in 100 mL of 3 mol·L − 1 HCl(aq) at 298.15 K are listed in Table 3 . In this table, m is the mass of samples, Δ sol H is the enthalpy of the solution, and Δ sol H m is the molar enthalpy of the solution of solute. The uncertainty is estimated as twice the standard deviation of the mean, namely, δ = in which n is experimental number (n = 5); x i is experimental value of each series of repeated measurements; and is mean value. Table 3 Molar enthalpies of solution of MgBO 2 (OH)(s) with different morphologies in 3 mol·dm − 3 HCl(aq) at 298.15 K and pressure p = 0.1 MPa. a, b No m /g Δ sol H /J Δ sol H m /kJ·mol − 1 MgBO 2 (OH) (A1) 1 0.1003 -84.2523 -70.66 2 0.1003 -84.3685 -70.76 3 0.1007 -85.5227 -71.44 4 0.1000 -84.6504 -71.21 5 0.1001 -84.7158 -71.19 Mean -71.05 ± 0.29 c MgBO 2 (OH) (A2) 1 0.1001 -85.9084 -72.10 2 0.1000 -85.8072 -72.18 3 0.1003 -85.9769 -72.11 4 0.1004 -86.0238 -72.07 5 0.1001 -85.9007 -72.17 Mean -72.13 ± 0.04 c MgBO 2 (OH) (A3) 1 0.1007 -71.3338 -59.59 2 0.1005 -71.3433 -59.72 3 0.1009 -72.0350 -60.06 4 0.1005 -71.9314 -60.21 5 0.1010 -71.5299 -59.57 Mean -59.83 ± 0.26 c a In each experiment, 100.00 cm 3 of 3.0093mol·L − 1 HCl(aq) was used; b Standard uncertainties u are u (T) = 0.001 K, u (p) = 2 kPa, and u (m) = 0.01 mg; c Expanded uncertainty U, which was estimated as twice the standard deviation of the mean with 0.95 level of confidence. Table 4 gives the thermochemical cycles used for the derivation of the standard molar enthalpies of formation of MgBO 2 (OH)(s) with different morphologies. The mean molar enthalpy of solution of H 3 BO 3 (s) of (22.60 ± 0.17) kJ·mol − 1 in 3 mol·L − 1 HCl(aq) was taken from the literature [34] . The enthalpy of dilution of HCl(aq) was calculated from the NBS tables[ 39 ]. The enthalpy changes for the formation of MgBO 2 (OH) from the reagents in the solid phase (reaction 5) were calculated to be -(54.83 ± 0.38)kJ·mol − 1 for sample A1, -(53.75 ± 0.25) kJ·mol − 1 for sample A2, -(66.05 ± 0.4) kJ·mol − 1 for sample A3 based on the thermochemical cycles. The standard molar enthalpies of formation of MgO(s), H 3 BO 3 (s) and H 2 O(l) were taken from the CODATA Key Values[ 40 ], namely − (601.60 ± 0.30) kJ·mol − 1 , -(1094.80 ± 0.80) kJ·mol − 1 and − (285.83 ± 0.04) kJ·mol − 1 , respectively. Δ f H m θ (MgBO 2 (OH),s)=Δ f H m θ (5)+Δ f H m θ (MgO,s)+Δ f H m θ (H 3 BO 3 ,s)-Δ f H m θ (H 2 O,l). From these data, the standard molar enthalpies of formation of MgBO 2 (OH) were calculated to be -(1465.40 ± 1.44) kJ·mol − 1 for sample A1, -(1464.32 ± 1.31) kJ·mol − 1 for sample A2, and − (1476.62 ± 1.46) kJ·mol − 1 for sample A3, respectively. Table 4 The standard molar reaction enthalpy of each virtual reaction in the thermodynamic cycle for calculating Δ f H m θ MgBO 2 (OH) a No Reaction Δ r H m θ /kJ·mol − 1 Refs. 1 H 3 BO 3 (s) + 252.313(HCl:17.575H 2 O) = H 3 BO 3 (aq) + 252.313(HCl:17.575H 2 O) 22.60 ± 0.17 [ 34 ] 2 MgO(s) + H 3 BO 3 (aq) + 252.313(HCl:17.575H 2 O) = MgCl 2 (aq) + H 3 BO 3 (aq) + 250.313(HCl:17.719H 2 O) -148.50 ± 0.18 [ 34 ] 3 252.313(HCl:17.575H 2 O) + H 2 O(l) = 252.313(HCl:17.579H 2 O) -0.02 ± 0.01 [ 34 ] 4 MgBO 2 (OH)(s) + 252.313(HCl:17.579H 2 O) = MgCl 2 (aq) + H 3 BO 3 (aq) + 250.313(HCl:17.719H 2 O) -71.05 ± 0.29 b (A1) -72.13 ± 0.04 b (A2) -59.83 ± 0.26 b (A3) This work 5 MgO(s) + H 3 BO 3 (s) = MgBO 2 (OH)(s) + H 2 O(l) -54.83 ± 0.38 c (A1) -53.75 ± 0.25 c (A2) -66.05 ± 0.40 c (A3) a Δ f H m θ (MgBO 2 (OH), s) = Δ f H m θ (5) + Δ f H m θ (MgO, s) + Δ f H m θ (H 3 BO 3 , s) – Δ f H m θ (H 2 O, l). c Uncertainty of the combined reaction is estimated as the square root of the sum of the squares of uncertainty of each individual reaction. From the results, it can be found that the standard enthalpy of formation of sample A3 is lower than the standard molar formation enthalpy of sample A1 and A2. This is because sample A3 is a single crystal with higher stability, while sample A1 and A2 are polycrystal with less stability, which is confirmed in the SAED image in Fig. 4 . The standard enthalpy of formation of sample A1 is slightly lower than that of sample A2, which may be because the size of the nanosheet assembled into sample A1 is similar to that of the nanowire assembled into sample A2. 4 Conclusions MgBO 2 (OH) with three different morphologies have been synthesized by hydrothermal method. The results show that MgBO 2 (OH) with rice panicle-like morphology have a single crystal structure, while the MgBO 2 (OH) with flower-like and sea urchin-like morphology are both polycrystalline structure. The overall particle size of the constituent units of MgBO 2 (OH) with flower-like is larger than that of sea urchin-like. By measuring enthalpies of solution through proper thermodynamic cycle, together with the standard molar enthalpies of formation of MgO(s), H 3 BO 3 (s) and H 2 O(l), the standard molar formation enthalpies of MgBO 2 (OH) with flower-like, sea urchin-like, and rice panicle-like morphologies were calculated to be -(1465.40 ± 1.44),-(1464.32 ± 1.31) and − (1476.62 ± 1.46) kJ·mol − 1 , respectively. The results show that the morphology and crystal structure of the sample have an effect on its standard molar enthalpy of formation, and the crystal structure has a greater influence. Declarations CRediT authorship contribution statement Jingxin Bi: Original draft writing-and sample preparation. Jia Zheng: Writing-reviewing and editing. Xiaoqin Feng: Sample characterization. Fanglong Cen: Data processing. Hongyan Zhang: Picture design. Hongsheng Huang: Experimental design, writing guidance and hardware support. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements This work is financially supported by the National Natural Science Foundation of China (No. 21963006) , key laboratory of energy chemistry in Guizhou universities (Qian Jiao Ji [2022]035) and high level talent scientific research startup project of Guizhou Institute of Technology (XJGC20190614). References Petrova, O., Taydakov, I., Anurova, M., Akkuzina, A., Avetisov, R., Khomyakov, A., Mozhevitina, E., Avetissov, I.: Luminescent hybrid materials based on an europium organic complex and borate glasses. J. Non-Cryst. Solids. 429 , 213-218 (2015) https://doi.org/10.1016/j.jnoncrysol.2015.09.012. Kindrat, I.I., Padlyak, B.V.: Luminescence properties and quantum efficiency of the Eu-doped borate glasses. Opt. Mater . 77 , 93-103 (2018) https://doi.org/10.1016/j.optmat.2018.01.019. Tao, Y.H., Huang, C., Lai, C.H., Huang, C.X., Yong, Q.:Biomimetic galactomannan/bentonite/graphene oxide film with superior mechanical and fire retardant properties by borate cross-linking. Carbohyd. Polym . 245 , 116508 (2020) https://doi.org/10.1016/j.carbpol.2020.116508. Attia, N., Ahmed, H., Yehia, D., Zaddin, Y.:Novel synthesis of nanoparticles-based back coating flame-retardant materials for historic textile fabrics conservation. J. Ind. Text. 46 (6), 1379-1392 (2017) https://doi.org/10.1177/1528083715619957. Zeng, Y., Gricius, Z., Weinell, C.E., Dam-Johansen, K., Ring, L., Kill, S.: Interactions between calcium carbonate and ammonium polyphosphate in low‐borate concentration hydrocarbon intumescent coatings. Fire. Mater. 46 (3), 499-512 (2022) https://doi.org/10.1002/fam.2994. Zuo, J., Liu, Z.H.: Controllable Synthesis, Characterization and Flame Retardant Properties of Three Kinds of α-4CaO·5B 2 O 3 ·7H 2 O Nanostructures Constructed by Nanoflakes. Acta. Chim. Sinica. 68 (24), 2535-2542 (2010) Miao, J., Guo, R.F., Liu, Z.H.: Preparation of BaO·4B 2 O 3 ·5H 2 O Nanomaterial and Evaluation of Its Flame Retardant Performance to PP by Thermal Decomposition Kinetics Method. Acta. Phys-Chim. Sin. 36 (6), 1905052 (2020) https://doi.org/10.3866/PKU.WHXB201905052 Zhang, L., Liu, Z.H.: Preparation of 2MgO·B 2 O 3 ·1.5H 2 O nanomaterials and evaluation of their flame retardant properties by a thermal decomposition kinetic method. J. Therm. Anal. Calorim. 129 (2), 715-719 (2017 https://doi.org/10.1007/s10973-017-6288-2. Liang, P., Liu, Z.H.: Controllable synthesis, growth mechanism and luminescence property of a novel monodisperse microsphere with a hole for Zn 8 [(BO 3 ) 3 O 2 (OH) 3 ]:Eu 3+ . Crystengcomm. 18 (8), 1311-1320 (2016) https://doi.org/10.1039/C5CE02018B. Liu, J.P., Li, Y.Y., Huang, X.T., Li, Z.K., Li, G.Y., Zeng, H.B.: Hydrothermal synthesis of single-crystal szaibelyite MgBO 2 (OH) nanobeltas a new host material for red-emitting rare-earth ions. Chem. Mater. 20 (1), 250-257 (2008) https://doi.org/10.1021/cm702719s. Sun, P.P., Chen, L.Y., Xu, L., Zhu, W.C.: Hierarchical porous MgBO 2 (OH) microspheres: Hydrothermal synthesis, thermal decomposition, and application as adsorbents for Congo red removal. Chinese. J. Chem. Eng . 26 (07), 1561-1569 (2018) https://doi.org/10.1016/j.cjche.2018.01.013. Ma, Y.Q., Liu, Z.H.: Excellent adsorption performance for Congo red on hierarchical porous magnesium borate microsphere prepared by a template-free hydrothermal method. J. Taiwan. Inst. Chem. E . 86 , 92-100 (2018) https://doi.org/10.1016/j.jtice.2018.02.015. Zhang, Z.Q., Zhu, W.C., Wang, R.G., Zhang, L.L., Zhu, L., Zhang, Q.: Ionothermal confined self-organization for hierarchical porous magnesium borate superstructures as highly efficient adsorbents for dye removal. J. Mater. Chem. A. 2 (45), 19167-19179 (2014) https://doi.org/10.1039/C4TA03580A. Konings, R.J.M., Cordfunke, E.H.P., Ouweltjes, W.: The standard enthalpy of formation of cesium monoborate: CsBO 2 . J. Chem. Thermodyn . 19 (2), 201-203 (1987) https://doi.org/10.1016/0021-9614(87)90112-1. Wang, J.F., Liang, P.: Thermochemical properties of alkaline-earth metals borates of a series of MB 8 O 11 (OH) 4 ·xH 2 O (M=Ca, Sr, Ba; x=0, 3). J. Chem. Thermodyn . 134 , 1-4 (2019) https://doi.org/10.1016/j.jct.2019.02.030. Liang, P., Li, S.Y.: Synthesis, characterization and standard molar enthalpies of formation of two zinc borates: 2ZnO·2B 2 O 3 ·3H 2 O and ZnB 4 O 7 . J. Chem. Thermodyn . 139 (C), 105868 (2019) https://doi.org/10.1016/j.jct.2019.07.010. Li, J., Li, B., Gao, S.Y.: Thermochemistry of hydrated lithium borates. J. Chem. Thermodyn. 30 (6), 681-688 (1998) https://doi.org/10.1006/jcht.1997.0324. Zhu, L.X., Yue, T., Gao, S.Y., Liu, Z.H., Xia, S.P.: Thermochemistry of rubidium calcium octaborate dodecahydrate. Thermochim. Acta . 402 (1), 241-245 (2003) https://doi.org/10.1016/S0040-6031(02)00539-7. Li, J., Li, B., Gao, S.Y.: Thermochemistry of hydrated potassium and sodium borates. J. Chem. Thermodyn. 30 (4), 425-430 (1998) https://doi.org/10.1006/jcht.1997.0304. Li, J., Gao, S.Y., Xia, S.P., Li, B., Hu, R.Z.: Thermochemistry of hydrated magnesium borates. J. Chem. Thermodyn. 29 (4), 491-497 (1997) https://doi.org/10.1006/jcht.1996.0183. Guo, R.F., Ma, Y.Q., Liu, Z.H.: Three hierarchical porous magnesium borate microspheres: a serial preparation strategy, growth mechanism and excellent adsorption behavior for Congo red. Rsc. Adv . 9 (35), 20009-20018 (2019) https://doi.org/10.1039/C9RA03654G. Liu, Z.H., Li, P., Li, L.Q., Jia, Q.X.: Synthesis, characterization and thermochemistry of K 2 B 5 O 8 (OH)·2H 2 O. Thermochim. Acta . 454 (1), 23-25 (2007) https://doi.org/10.1016/j.tca.2006.12.008. Liu, Z.H., Zuo, C.F., Li, S.Y.: Synthesis and thermochemistry of 2CaO·B 2 O 3 ·H 2 O. Thermochim. Acta. 424 (1-2), 59-62 (2004) https://doi.org/10.1016/j.tca.2004.05.029. Liu, Z.H., Li, P., Zuo, C.F.: Standard Molar Enthalpies of Formation for the Two Hydrated Calcium Borates xCaO·5B 2 O 3 ·yH 2 O (x=2 and 4, y=5 and 7). J. Chem. Eng. Data. 51 (1), 272-275 (2006) https://doi.org/10.1021/je050383m. Liu, Z.H., Wang, Y., Huang, H.S.: Determination of Standard Molar Enthalpies of Formation for the Two Barium Borates BaB 2 O 4 ·xH 2 O (x=4, 0) by Microcalorimetry. J. Chem. Eng. Data . 52 (2), 487-490 (2007) https://doi.org/10.1021/je060422+. Huang, H.S., Liu, Z.H.: Synthesis and thermochemistry of SrB 2 O 4 ·2.5H 2 O and SrB 6 O 10 ·5H 2 O. Thermochim. Acta . 463 (1-2), 87-89 (2007) https://doi.org/10.1016/j.tca.2007.07.010. Liu, Z.H., Hu, M.C.: Synthesis and thermochemistry of MgO·3B 2 O 3 ·3.5H 2 O. Thermochim. Acta. 403 (2), 181–184 (2003) https://doi.org/10.1016/S0040-6031(03)00058-3. Liu, Z.H., Hu, M.C.: Synthesis, characterization, and thermochemistry of a new form of 2MgO·3B 2 O 3 ·17H 2 O. Thermochim. Acta. 414 (2), 215–218 (2004) https://doi.org/10.1016/j.tca.2003.12.026. Liu, Z.H., Zhao, U., Hu, M.C.: Synthesis, Characterization and Thermochemistry of 2MgO·B 2 O 3 ·1.5H 2 O. Chinese. J. Chem . 21 (12), 1569-1572 (2010) https://doi.org/10.1002/cjoc.20030211211. Liu, J., Ma, X.Y., Liu, Z.H.: Preparation of Ca[B 6 O 9 (OH) 2 ]·3H 2 O nanomaterials by a phase transformation method and their flame retardant and thermodynamic properties. Powder. Technol. 246 , 26–30 (2013) https://doi.org/10.1016/j.powtec.2013.05.001. Geng, Y.J., Liu, Z.H.: Preparation and thermodynamic characterization of 2CaO·B 2 O 3 ·H 2 O nanomaterials with enhanced flame retardant properties. Colloid. Surface. A . 522 (5), 563–568 (2017) https://doi.org/10.1016/j.colsurfa.2017.03.044. Guo, Y.W., Mao, L., Rong, F., Liu, Z.H.: Preparation of Zn 3 B 10 O 18 ·14H 2 O nanomaterials and their thermochemical properties. Thermochim. Acta. 539 , 56–61 (2012) https://doi.org/10.1016/j.tca.2012.04.007. Zhu, W.C., Zhang, X.Y., Zhang, Q., Xing, L.,Zhu, S.L.: Subunit contribution model for thermodynamic properties of borates and its application in hydrothermal synthesis of MgBO 2 (OH) nanowhiskers. CIESC Journal. 64 (2), 443-451 (2013) https://doi.org/10.3969/j.issn.0438-1157.2013.02.007 Liu, Z.H., Hu, M.C.: New synthetic method and thermochemistry of szaibelyite. Thermochim. Acta. 411 (1), 27-29 (2004) https://doi.org/10.1016/j.tca.2003.07.009. Yu, H.G., Liu, Y., Tan, Z.C., Dong, J.X., Zou, T.J., Huang, X.M., Qu, S.S.: A solution-reaction isoperibol calorimeter and standard molar enthalpies of formation of Ln (hq)2Ac(Ln= La, Pr), Thermochim. Acta. 401 (2), 217-224 (2003) https://doi.org/10.1016/S0040-6031(02)00566-X. Archer, D.G.: Thermodynamic properties of the KCl+H 2 O system. J. Phys. Chem. Ref. Data. 28 (1), 1-17 (1999) https://doi.org/10.1063/1.556034. Rychlý, R., Pekárek, V.: The use of potassium chloride and tris(hydroxymethyl)aminomethane as standard substances for solution calorimetry. J. Chem. Thermodyn. 9 (4), 391–396 (1977) https://doi.org/10.1016/0021-9614(77)90060-X. Li, J., Xia, S.P., Gao, S.Y.: FT-IR and Raman spectroscopic study of hydrated borates. Spectrochim. Acta. A. 51 (4), 519-532 (1995) https://doi.org/10.1016/0584-8539(94)00183-C. Wagman, D.D., Evans, W.H., Parker, V.B.: The NBS tables of chemical thermodynamic properties. J. Phys. Chem. Ref. Data. 11 (Suppl. 2) (1982) https://doi.org/ 10.1063/1.555845.https://doi.org/ 10.1063/1.555845. Cox, J.D., Wagman, D.D., Medvedev, V.A.: CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989 https://api.semanticscholar.org/CorpusID:91473815. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4137398","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":282081908,"identity":"c69f11db-8bbf-455f-a13c-8e85a6b19da3","order_by":0,"name":"Jingxin Bi","email":"","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Jingxin","middleName":"","lastName":"Bi","suffix":""},{"id":282081909,"identity":"9a16ebd1-c90c-4073-b0a7-976ba6261e83","order_by":1,"name":"Xiaoqin Feng","email":"","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Xiaoqin","middleName":"","lastName":"Feng","suffix":""},{"id":282081910,"identity":"517ddf11-7f5d-4105-ae3a-f03e545e9e8c","order_by":2,"name":"Jia Zheng","email":"","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Jia","middleName":"","lastName":"Zheng","suffix":""},{"id":282081911,"identity":"85e3d9e8-487c-4e60-a110-d0bb4131d717","order_by":3,"name":"Fanglong Cen","email":"","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Fanglong","middleName":"","lastName":"Cen","suffix":""},{"id":282081914,"identity":"0a6e4c92-bae6-41de-abeb-c0b4885ed323","order_by":4,"name":"Hongyan Zhang","email":"","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Hongyan","middleName":"","lastName":"Zhang","suffix":""},{"id":282081916,"identity":"cc07e4cf-703c-4fd1-ba17-b6d9b0484c47","order_by":5,"name":"Hongsheng Huang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvklEQVRIiWNgGAWjYBACefbm4x8+/rNh5idai2HPsTTGGWxp7JINROu54WPGzMN2mN/gALE6GGfwmD3m4UmTNj6evIHhR8U2wlrYpdvKDedI2BibnXlWwNhz5jYRtsw5vEHijUFastmNHANmxjYitDDcSDCQ4Ek4XL95BvFaUswkeQ4cZjaQIFYLMJCTDWc2pDFLAP1ykCi/AKPy4IOPDcCobE/e+OBHBTEOQ4AE4qMGoYVUHaNgFIyCUTBCAAAJoj9Y8O7o8wAAAABJRU5ErkJggg==","orcid":"","institution":"Guizhou Institute of Technology","correspondingAuthor":true,"prefix":"","firstName":"Hongsheng","middleName":"","lastName":"Huang","suffix":""}],"badges":[],"createdAt":"2024-03-20 13:12:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4137398/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4137398/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":53376317,"identity":"e891d312-897d-426e-b4af-ca9ee4acb339","added_by":"auto","created_at":"2024-03-25 09:17:03","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":97682,"visible":true,"origin":"","legend":"\u003cp\u003eThe designed thermochemical cycle of MgBO\u003csub\u003e2\u003c/sub\u003e(OH)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4137398/v1/b61cdf433fd55d693e8190a5.png"},{"id":53376295,"identity":"e3e6fb85-2e34-4132-9a7e-57e2a021b6b5","added_by":"auto","created_at":"2024-03-25 09:17:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1817671,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of samples: (a)A1, (b)A2, (c)A3\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4137398/v1/f08be35e7e16784f3ef0b5af.png"},{"id":53376318,"identity":"3299a29a-476d-4c75-ab61-83fbfc02cde9","added_by":"auto","created_at":"2024-03-25 09:17:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1939399,"visible":true,"origin":"","legend":"\u003cp\u003eThe FT-IR spectra of samples: (a)A1, (b)A2, (c)A3.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4137398/v1/e4ea644c7dd7ace5d46ded13.png"},{"id":53376291,"identity":"c631f681-44f2-4e12-b799-074344b25997","added_by":"auto","created_at":"2024-03-25 09:17:00","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":360458,"visible":true,"origin":"","legend":"\u003cp\u003eThe SEM images of samples: (a, b)A1, (e, f)A2, (i, j)A3; TEM images of samples: (c, d)A1, (g, h)A2, (k, l)A3 and the selected area electronic diffraction (SAED) of samples:(d)A1, (h)A2, (l)A3\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4137398/v1/02236de04f772c385c4e4b06.png"},{"id":53818619,"identity":"96e93c0f-9f7f-486a-a638-dc8788b0bc75","added_by":"auto","created_at":"2024-03-31 21:07:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":700094,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4137398/v1/137a1acb-67d7-4eb0-942c-84ccb4c7598e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Synthesis and thermodynamic properties of nano magnesium borate MgBO 2 (OH) with three different morphologies","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eBorate have been used widely in various materials due to its physical and chemical properties such as flame retardant, heat resistance, high hardness, high strength, wear resistance and light weight[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Among them, magnesium borate was mainly used in luminous materials, flame retardant materials, coatings and other materials due to its high stability, chemical stability and low cost[\u003cspan additionalcitationids=\"CR3 CR4\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The results show that the morphology and particle size of the sample has a great influence on its properties. For example, the flame retardancy of nano α-4CaO\u0026middot;5B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;7H\u003csub\u003e2\u003c/sub\u003eO with spherical-like, pupal-like, and sheet-like morphology is enhanced sequentially[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]; the flame-retardant properties of BaO\u0026middot;4B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;5H\u003csub\u003e2\u003c/sub\u003eO nanoribbons and nanosheets increases sequentially[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]; the flame retardancy of 2MgO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;1.5H\u003csub\u003e2\u003c/sub\u003eO with nanowire morphology is superior to that of sample with nanorod morphology[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]; among zinc borate (Zn\u003csub\u003e8\u003c/sub\u003e[(BO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e(OH)\u003csub\u003e3\u003c/sub\u003e]:Eu\u003csup\u003e3+\u003c/sup\u003e) phosphors with six different morphologies, zinc borate phosphors with hexahedral morphologies exhibit the strongest luminescence intensity[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, the synthesis and properties research of borate with different morphologies and particle sizes have received increasing attention.\u003c/p\u003e \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH)(2MgO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO) is a kind of translucent mineral widely distributed in nature. MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with different morphologies and particle sizes has been prepared using hydrothermal and ion thermal methods, and its properties have been studied. For example, Liu et al.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] obtained nanospherical-like MgBO\u003csub\u003e2\u003c/sub\u003e(OH):Eu\u003csup\u003e3+\u003c/sup\u003e, Y\u003csup\u003e3+\u003c/sup\u003e with good luminescent properties by hydrothermal method, indicating that MgBO\u003csub\u003e2\u003c/sub\u003e(OH) is a good luminescent material matrix. Sun[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and Liu et al.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] synthesized hierarchical porous MgBO\u003csub\u003e2\u003c/sub\u003e(OH) microspheres by hydrothermal method, and the results showed that this sample has potential application prospects as an efficient adsorbent for removing Congo red (CR) or other organic dyes from wastewater. Zhang et al.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] prepared porous MgBO\u003csub\u003e2\u003c/sub\u003e(OH) nanospheres by ionic thermal method, which have potential advantages in dye adsorption and heterogeneous catalysis. The above results indicate that MgBO\u003csub\u003e2\u003c/sub\u003e(OH) has good properties in luminescence, mechanics, adsorption and other aspects.\u003c/p\u003e \u003cp\u003eThermodynamic properties can provide information about the stability and reactivity of the substances, playing a very important role in scientific research and industrial production. In the past few decades, researchers have carried out many studies on the thermodynamic properties of borates using calorimetry. For example, Konings R.J.M et al.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] measured the standard molar enthalpies of formation of CsBO\u003csub\u003e2\u003c/sub\u003e; Wang et al.[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] determined the standard molar formation enthalpies of BaB\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e11\u003c/sub\u003e(OH)\u003csub\u003e4\u003c/sub\u003e\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO and MB\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e11\u003c/sub\u003e(OH)\u003csub\u003e4\u003c/sub\u003e\u0026middot;xH\u003csub\u003e2\u003c/sub\u003eO (M\u0026thinsp;=\u0026thinsp;Ca, Sr, Ba); Liang et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] determined the standard molar enthalpies of formation of 2ZnO\u0026middot;2B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO and ZnB\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e; the standard molar enthalpies of formation of alkali metal and alkaline earth metal hydrated borates such as lithium borate[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], sodium borate[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], potassium borate[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], calcium borate[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], barium borate[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] and strontium borate[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] were tested by Gao[\u003cspan additionalcitationids=\"CR18 CR19\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and Liu et al.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. At present, a few studies on the thermodynamic properties of hydrated magnesium borate have been reported, such as MgO\u0026middot;3B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;3.5H\u003csub\u003e2\u003c/sub\u003eO[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], 2MgO\u0026middot;3B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;17H\u003csub\u003e2\u003c/sub\u003eO[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] and 2MgO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;1.5H\u003csub\u003e2\u003c/sub\u003eO[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Research has shown that the thermodynamic properties of materials are related to their morphology and particle size. For example, Liu et al.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] found that the standard molar formation enthalpy of formation of nano Ca[B\u003csub\u003e6\u003c/sub\u003eO\u003csub\u003e9\u003c/sub\u003e(OH)\u003csub\u003e2\u003c/sub\u003e]\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO with sheet-like, ellipsoidal-like and flower-like morphologies decreased(more exothermic enthalpy) sequentially; Geng et al.[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] found that the standard molar enthalpy of 2CaO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO increases(less exothermic enthalpy) with the decrease of its particle size; Guo et al.[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] found that the standard molar formation enthalpy of Zn\u003csub\u003e3\u003c/sub\u003eB\u003csub\u003e10\u003c/sub\u003eO\u003csub\u003e18\u003c/sub\u003e\u0026middot;14H\u003csub\u003e2\u003c/sub\u003eO increases (less exothermic enthalpy) with the decrease of its particle size.\u003c/p\u003e \u003cp\u003eZhu et al.[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] determined the thermodynamic properties of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) nanowhiskers, but there have been no comparative studies on the thermodynamic properties of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with different morphologies. In this paper, the MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with three different morphologies were prepared by hydrothermal method, and the standard molar enthalpies of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with different morphologies were measured, and the influence of morphologies on their thermodynamic properties was analyzed.\u003c/p\u003e"},{"header":"2 Experimental","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e2.1 Synthesis of samples\u003c/h2\u003e\n \u003cp\u003eAll the chemical reagents used in the experiment were analytical grade.\u003c/p\u003e\n \u003cp\u003eTypically, 1.529 g of MgCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO, 0.928 g of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e and 0.300 g of NaOH (molar ratio of Mg:B:OH\u0026thinsp;=\u0026thinsp;1:2:1) were individually dissolved into 10.0, 30.0 and 10.0 mL of deionized (DI) water. Subsequently, the solutions of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e and NaOH were successively dropwise added to the above MgCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO solution under vigorous magnetic stirring, and 0.1g sodium dodecyl sulfonate was added to the MgCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO solution. Having been agitated for 10 min, the as-formed precursor slurry was transferred into a Teflon-lined stainless steel autoclave, and maintained at 180\u0026deg;C for 12 h. Finally, the obtained white precipitate were collected by filtration and washed with distilled water and ethanol for several times. The flower-like MgBO\u003csub\u003e2\u003c/sub\u003e(OH) named A1 was obtained after drying at 70\u0026deg;C for 12 h.\u003c/p\u003e\u003cbr\u003e\n \u003cp\u003e5.12 g Mg(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO and 4.34 g NH\u003csub\u003e4\u003c/sub\u003eB\u003csub\u003e5\u003c/sub\u003eO\u003csub\u003e8\u003c/sub\u003e\u0026middot;4H\u003csub\u003e2\u003c/sub\u003eO were dissolved in 50 mL of distilled water. Then the resulting solution was transferred into the Teflon-lined autoclave after stirring for 10 min and maintained at 160\u0026deg;C for 12 h. After the reaction was completed, the product was cooled to room temperature, filtered, washed with deionized water and anhydrous ethanol for several times. The sea urchin-like microstructure MgBO\u003csub\u003e2\u003c/sub\u003e(OH) named A2 was obtained after drying at 60\u0026deg;C for 12 h.\u003c/p\u003e\u0026nbsp;1.6 g NaOH, 3.66 g H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e and 4.06 g MgCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO dissolve in 10.0 mL, 30.0 mL and 10.0mL distilled water, respectively. Then the resulting solution was transferred into the Teflon-lined autoclave after stirring for 10 min and maintained at 220\u0026deg;C for 6 h. After the reaction was completed, the product was cooled to room temperature, filtered, washed with deionized water and anhydrous ethanol for several times. The rice panicle-like microstructure MgBO\u003csub\u003e2\u003c/sub\u003e(OH) named A3 was obtained after drying at 60\u0026deg;C for 6 h.\u003ch2\u003e2.2 Characterization of the samples\u003c/h2\u003e\n \u003cp\u003eAt 298\u0026thinsp;\u0026plusmn;\u0026thinsp;1K and 0.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01MPa, the phase composition and crystallinity of the products are characterized by X-ray powder diffraction (XRD, Ultima Ⅳ, Cu target), and Fourier infrared spectrometer (FI-IR, Nicolet NEXUS 670) were used to characterize the phase of the samples. The morphologies and sizes of the samples were investigated by scanning electron microscopy (SEM, Nova Nano 450) and transmission electron microscopy(TEM, JEOL JEM-F 200).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e2.3Calorimetric experiment\u003c/h2\u003e\n \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) can be regarded as the products of the following reactions, respectively:\u003c/p\u003e\n \u003cp\u003eMgO(s)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(aq)\u0026thinsp;=\u0026thinsp;MgBO\u003csub\u003e2\u003c/sub\u003e(OH)(s)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO(l)\u003c/p\u003e\n \u003cp\u003eThe thermodynamic cycle designed for the determination of the standard molar enthalpy of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) is shown in Fig. \u003cspan\u003e1\u003c/span\u003e. The 3.00 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) solvent can dissolve all components of virtual reaction (5), and its concentration is (3.0093\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0001) mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e determined by titration with standard sodium carbonate. Using its density of 1.019 g\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e (taken from the Handbook of Chemistry), its concentration can also be expressed as the form of HCl\u0026middot;17.575H\u003csub\u003e2\u003c/sub\u003eO[\u003cspan\u003e34\u003c/span\u003e].\u003c/p\u003e\u003cbr\u003e\n \u003cp\u003eThe molar enthalpies of solution of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s), MgO(s) in 3 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) were measured, namely \u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(1), \u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(4), respectively. The calculated amount of MgO(s) was dissolved in (hydrochloric acid\u0026thinsp;+\u0026thinsp;boric acid) aqueous solution which consisted of 3 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) and the calculated amount of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) (\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(2)). In all these determinations, strict control of the stoichiometry in each step of the calorimetric cycle must be observed, with the objective that the dissolution of the reactants give the same composition as those of the products in reactions. The standard molar enthalpy of dissolution of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) in 3.0093 mol\u0026middot;dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e HCl(aq) was determined by an application calorimeter at 298.15 K. Applying Hess\u0026rsquo;s law, the enthalpy of reaction (5) (\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(5)) can be calculated according to the following expression:\u003c/p\u003e\n \u003cp\u003e\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(5)=\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(1)+\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(2)-\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(3)-\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(4)\u003c/p\u003e\n \u003cp\u003ewhere \u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(3) is the enthalpy of dilution of HCl(aq).\u003c/p\u003e\n \u003cp\u003eThe standard molar enthalpy of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) can be obtained by combining the standard molar enthalpy of formation of MgO(s), H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) and H\u003csub\u003e2\u003c/sub\u003eO(l) in the virtual reaction.\u003c/p\u003e\n \u003cp\u003eAll the enthalpies of solution were measured with an SRC 100 heat conduction microcalorimeter (Wuhan Machinery Technology Co. China), which has been described in detail previously[\u003cspan\u003e35\u003c/span\u003e]. To check the performance of the calorimeter, the enthalpy of dissolution of KCl (mass fraction\u0026thinsp;\u0026ge;\u0026thinsp;0.9999) in 100 mL deionized water at T\u0026thinsp;=\u0026thinsp;298.15K was determined to be (17.564\u0026thinsp;\u0026plusmn;\u0026thinsp;0.026) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Table.1) and the enthalpy of solution of Tris (hydroxymethyl)aminoethane) (mass fraction\u0026thinsp;\u0026ge;\u0026thinsp;0. 9999) in 100 mL HCl(aq) (0.100\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0001) mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at T\u0026thinsp;=\u0026thinsp;298.15K was determined to be (-29.677\u0026thinsp;\u0026plusmn;\u0026thinsp;0.045) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Table.2) which are consistent with the results of the measurements reported in the literature[\u003cspan\u003e36\u003c/span\u003e, \u003cspan\u003e37\u003c/span\u003e]. The results shows that the device used for measuring the enthalpy of the solution in this work is reliable.\u003c/p\u003e\n \u003cdiv\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eThe enthalpy of solution of KCl in water at 298.15 K.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003eNo\u003cbr\u003e\u003c/th\u003e\n \u003cth align=\"left\"\u003em /g\u003cbr\u003e\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026Delta;\u003csub\u003esol\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e/kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003cbr\u003e\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e1\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.3722\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.597\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e2\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.3704\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.576\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e3\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.3715\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.526\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e4\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.3749\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.545\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e5\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.3752\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.580\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003eMean\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e17.564\u0026thinsp;\u0026plusmn;\u0026thinsp;0.026\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\u003cbr\u003e\n \u003cdiv\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eThe enthalpy of solution of Tris in (0.100\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0001) mol\u0026middot;dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e HCl at 298.15 K\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003eNo\u003cbr\u003e\u003c/th\u003e\n \u003cth align=\"left\"\u003em /g\u003cbr\u003e\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026Delta;\u003csub\u003esol\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e/kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003cbr\u003e\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e1\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.5000\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.667\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e2\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.5003\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.621\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e3\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.5000\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.687\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e4\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.5003\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.758\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e5\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e0.5007\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.655\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003eMean\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd align=\"char\"\u003e-29.677\u0026thinsp;\u0026plusmn;\u0026thinsp;0.045\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"3 Results and discussion","content":"\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e3.1 Characterization of the synthetic sample\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan\u003e2\u003c/span\u003e gives the XRD patterns of the prepared samples A1, A2 and A3. It can be seen from the figure that all diffraction peaks of samples A1, A2 and A3 are basically consistent with the standard card (JCPDS:039-1370), and no other impurity phase exists. Samples A1, A2 and A3 can be considered to be MgBO\u003csub\u003e2\u003c/sub\u003e(OH).\u003c/p\u003e\n \u003cp\u003eThe FT-IR spectra of sample A1, A2 and A3 are shown in Fig. \u003cspan\u003e3\u003c/span\u003ea, b, c, respectively. The FT-IR spectrum of synthetic samples exhibit the following absorption bands and they were assigned referring to literature[\u003cspan\u003e38\u003c/span\u003e]. The peak shape and peak position of the three samples are consistent. In Fig. \u003cspan\u003e3\u003c/span\u003e, the band at 3290\u0026ndash;3580 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the stretching of O-H bond. The band at 1627 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is assigned to the H-O-H bending mode, which shows this compound contains crystal water. The bands at 1450cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1396 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 923 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are the asymmetric and symmetric stretching modes of B\u003csub\u003e(3)\u003c/sub\u003e-O, respectively. The band at 1280 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1174 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are in-plane bending of B-O-H. The band at 1068 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1006cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 785 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are the asymmetric and symmetric stretching modes of B\u003csub\u003e(4)\u003c/sub\u003e-O, respectively. The band at 620\u0026ndash;713 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the out-of-plane bending of B\u003csub\u003e(3)\u003c/sub\u003e-O. The band at 557 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the bending of B\u003csub\u003e(3)\u003c/sub\u003e-O.\u003c/p\u003e\n \u003cp\u003eThe low-magnification, high-magnification SEM images, TEM images and SAED images of three samples with different morphologies are shown in Fig. \u003cspan\u003e4\u003c/span\u003e. From Fig. \u003cspan\u003e4\u003c/span\u003e (a-d), it can be observed that sample A1 exhibits the flower-like microstructure, which is assembled by nanosheets with an average length of 500 nm, a width of 500 nm and thickness of about 10 nm. As shown in Fig. \u003cspan\u003e4\u003c/span\u003e (e-h), sample A2 exhibits the sea urchin-like microstructure, which is constructed by a large number of nanowires with an average length of 500 nm and diameter of 10 nm. From Fig. \u003cspan\u003e4\u003c/span\u003e (i-l), it can be seen that sample A3 exhibits the rice panicle-like microstructure, which is composed of nanorods with an average length of 100 nm and diameter of 20 nm. It can be found from SAED images (Fig. \u003cspan\u003e4\u003c/span\u003e. d, h, l(inset)) that the samples A1 and A2 are polycrystalline structure, while A3 is monocrystalline structure.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003e3.2 Results of the calorimetric experiment\u003c/h2\u003e\n \u003cp\u003eThe molar enthalpies of solution of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with different morphologies in 100 mL of 3 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) at 298.15 K are listed in Table \u003cspan\u003e3\u003c/span\u003e. In this table, m is the mass of samples, \u0026Delta;\u003csub\u003esol\u003c/sub\u003eH is the enthalpy of the solution, and \u0026Delta;\u003csub\u003esol\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e is the molar enthalpy of the solution of solute. The uncertainty is estimated as twice the standard deviation of the mean, namely, \u0026delta; \u003cspan\u003e\u003cspan\u003e=\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1711357473.png\"\u003e\u003c/span\u003e\u003c/span\u003e in which n is experimental number (n\u0026thinsp;=\u0026thinsp;5); \u003cem\u003ex\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e is experimental value of each series of repeated measurements; and \u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1711357367.png\"\u003e\u0026nbsp;is mean value.\u003c/p\u003e\n \u003cdiv\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eMolar enthalpies of solution of MgBO\u003csub\u003e2\u003c/sub\u003e(OH)(s) with different morphologies in 3 mol\u0026middot;dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e HCl(aq) at 298.15 K and pressure p\u0026thinsp;=\u0026thinsp;0.1 MPa. \u003csup\u003ea, b\u003c/sup\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003em /g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta;\u003csub\u003esol\u003c/sub\u003eH /J\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta;\u003csub\u003esol\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e /kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) (A1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-84.2523\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-70.66\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-84.3685\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-70.76\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-85.5227\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-84.6504\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-84.7158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) (A2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-85.9084\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-85.8072\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-85.9769\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-86.0238\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-85.9007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) (A3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.3338\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.3433\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59.72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1009\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.0350\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-60.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.9314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-60.21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1010\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.5299\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e\u003csup\u003ea\u003c/sup\u003e In each experiment, 100.00 cm\u003csup\u003e3\u003c/sup\u003e of 3.0093mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) was used;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e\u003csup\u003eb\u003c/sup\u003e Standard uncertainties u are u (T)\u0026thinsp;=\u0026thinsp;0.001 K, u (p)\u0026thinsp;=\u0026thinsp;2 kPa, and u (m)\u0026thinsp;=\u0026thinsp;0.01 mg;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003csup\u003ec\u003c/sup\u003e Expanded uncertainty U, which was estimated as twice the standard deviation of the mean with 0.95 level of confidence.\u003c/p\u003e\n \u003cp\u003eTable \u003cspan\u003e4\u003c/span\u003e gives the thermochemical cycles used for the derivation of the standard molar enthalpies of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH)(s) with different morphologies. The mean molar enthalpy of solution of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) of (22.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in 3 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) was taken from the literature\u003csup\u003e[34]\u003c/sup\u003e. The enthalpy of dilution of HCl(aq) was calculated from the NBS tables[\u003cspan\u003e39\u003c/span\u003e]. The enthalpy changes for the formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) from the reagents in the solid phase (reaction 5) were calculated to be -(54.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38)kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A1, -(53.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A2, -(66.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A3 based on the thermochemical cycles. The standard molar enthalpies of formation of MgO(s), H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) and H\u003csub\u003e2\u003c/sub\u003eO(l) were taken from the CODATA Key Values[\u003cspan\u003e40\u003c/span\u003e], namely \u0026minus;\u0026thinsp;(601.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, -(1094.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.80) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and \u0026minus;\u0026thinsp;(285.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively.\u003c/p\u003e\n \u003cp\u003e\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(MgBO\u003csub\u003e2\u003c/sub\u003e(OH),s)=\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(5)+\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(MgO,s)+\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e,s)-\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(H\u003csub\u003e2\u003c/sub\u003eO,l).\u003c/p\u003e\n \u003cp\u003eFrom these data, the standard molar enthalpies of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) were calculated to be -(1465.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A1, -(1464.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A2, and \u0026minus;\u0026thinsp;(1476.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.46) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for sample A3, respectively.\u003c/p\u003e\n \u003cdiv\u003e\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 4\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eThe standard molar reaction enthalpy of each virtual reaction in the thermodynamic cycle for calculating \u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eReaction\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e\u0026Delta;\u003csub\u003er\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e/kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRefs.\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s)\u0026thinsp;+\u0026thinsp;252.313(HCl:17.575H\u003csub\u003e2\u003c/sub\u003eO)\u0026thinsp;=\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;252.313(HCl:17.575H\u003csub\u003e2\u003c/sub\u003eO)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e22.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e[\u003cspan\u003e34\u003c/span\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMgO(s)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;252.313(HCl:17.575H\u003csub\u003e2\u003c/sub\u003eO)\u0026thinsp;=\u0026thinsp;MgCl\u003csub\u003e2\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;250.313(HCl:17.719H\u003csub\u003e2\u003c/sub\u003eO)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e-148.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e[\u003cspan\u003e34\u003c/span\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e252.313(HCl:17.575H\u003csub\u003e2\u003c/sub\u003eO)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO(l)\u0026thinsp;=\u0026thinsp;252.313(HCl:17.579H\u003csub\u003e2\u003c/sub\u003eO)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e-0.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e[\u003cspan\u003e34\u003c/span\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH)(s)\u0026thinsp;+\u0026thinsp;252.313(HCl:17.579H\u003csub\u003e2\u003c/sub\u003eO)\u0026thinsp;=\u0026thinsp;MgCl\u003csub\u003e2\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(aq)\u0026thinsp;+\u0026thinsp;250.313(HCl:17.719H\u003csub\u003e2\u003c/sub\u003eO)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-71.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003csup\u003eb\u003c/sup\u003e(A1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-72.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003csup\u003eb\u003c/sup\u003e(A2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003csup\u003eb\u003c/sup\u003e(A3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThis\u003c/p\u003e\n \u003cp\u003ework\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMgO(s)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s)\u0026thinsp;=\u0026thinsp;MgBO\u003csub\u003e2\u003c/sub\u003e(OH)(s)\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO(l)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-54.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003csup\u003ec\u003c/sup\u003e(A1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-53.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003csup\u003ec\u003c/sup\u003e(A2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-66.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003csup\u003ec\u003c/sup\u003e(A3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e\u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(MgBO\u003csub\u003e2\u003c/sub\u003e(OH), s) = \u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(5) + \u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(MgO, s) + \u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e, s) \u0026ndash; \u0026Delta;\u003csub\u003ef\u003c/sub\u003eH\u003csub\u003em\u003c/sub\u003e\u003csup\u003e\u0026theta;\u003c/sup\u003e(H\u003csub\u003e2\u003c/sub\u003eO, l).\u003c/p\u003e\n \u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1711357554.png\"\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e\u003csup\u003ec\u003c/sup\u003eUncertainty of the combined reaction is estimated as the square root of the sum of the squares of uncertainty of each individual reaction.\u003c/p\u003e\n \u003cp\u003eFrom the results, it can be found that the standard enthalpy of formation of sample A3 is lower than the standard molar formation enthalpy of sample A1 and A2. This is because sample A3 is a single crystal with higher stability, while sample A1 and A2 are polycrystal with less stability, which is confirmed in the SAED image in Fig. \u003cspan\u003e4\u003c/span\u003e. The standard enthalpy of formation of sample A1 is slightly lower than that of sample A2, which may be because the size of the nanosheet assembled into sample A1 is similar to that of the nanowire assembled into sample A2.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4 Conclusions","content":"\u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) with three different morphologies have been synthesized by hydrothermal method. The results show that MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with rice panicle-like morphology have a single crystal structure, while the MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with flower-like and sea urchin-like morphology are both polycrystalline structure. The overall particle size of the constituent units of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with flower-like is larger than that of sea urchin-like. By measuring enthalpies of solution through proper thermodynamic cycle, together with the standard molar enthalpies of formation of MgO(s), H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) and H\u003csub\u003e2\u003c/sub\u003eO(l), the standard molar formation enthalpies of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with flower-like, sea urchin-like, and rice panicle-like morphologies were calculated to be -(1465.40 ± 1.44),-(1464.32 ± 1.31) and − (1476.62 ± 1.46) kJ·mol\u003csup\u003e− 1\u003c/sup\u003e, respectively. The results show that the morphology and crystal structure of the sample have an effect on its standard molar enthalpy of formation, and the crystal structure has a greater influence.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eJingxin Bi:\u003c/strong\u003e Original draft\u0026nbsp;writing-and sample\u0026nbsp;preparation. \u003cstrong\u003eJia Zheng:\u003c/strong\u003e Writing-reviewing and editing. \u003cstrong\u003eXiaoqin Feng:\u003c/strong\u003e Sample characterization. \u003cstrong\u003eFanglong Cen:\u0026nbsp;\u003c/strong\u003eData processing. \u003cstrong\u003eHongyan Zhang:\u003c/strong\u003e Picture\u0026nbsp;design. \u003cstrong\u003eHongsheng Huang:\u003c/strong\u003e Experimental design, writing guidance and hardware support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is financially supported by the National Natural Science Foundation of China (No. 21963006) , key laboratory of energy chemistry in Guizhou universities (Qian Jiao Ji [2022]035) and high level talent scientific research startup project of Guizhou Institute of Technology (XJGC20190614).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePetrova, O., Taydakov, I., Anurova, M., Akkuzina, A., Avetisov, R., Khomyakov, A., Mozhevitina, E., Avetissov, I.: Luminescent hybrid materials based on an europium organic complex and borate glasses. \u003cem\u003eJ. Non-Cryst. Solids.\u003c/em\u003e\u003cstrong\u003e429\u003c/strong\u003e, 213-218 (2015) https://doi.org/10.1016/j.jnoncrysol.2015.09.012.\u003c/li\u003e\n\u003cli\u003eKindrat, I.I., Padlyak, B.V.: Luminescence properties and quantum efficiency of the Eu-doped borate glasses. \u003cem\u003eOpt. Mater\u003c/em\u003e. \u003cstrong\u003e77\u003c/strong\u003e,\u003cstrong\u003e \u003c/strong\u003e93-103 (2018) https://doi.org/10.1016/j.optmat.2018.01.019.\u003c/li\u003e\n\u003cli\u003eTao, Y.H., Huang, C., Lai, C.H., Huang, C.X., Yong, Q.:Biomimetic galactomannan/bentonite/graphene oxide film with superior mechanical and fire retardant properties by borate cross-linking. \u003cem\u003eCarbohyd. Polym\u003c/em\u003e. \u003cstrong\u003e245\u003c/strong\u003e, 116508 (2020) https://doi.org/10.1016/j.carbpol.2020.116508.\u003c/li\u003e\n\u003cli\u003eAttia, N., Ahmed, H., Yehia, D., Zaddin, Y.:Novel synthesis of nanoparticles-based back coating flame-retardant materials for historic textile fabrics conservation. \u003cem\u003eJ. Ind. Text.\u003c/em\u003e\u003cstrong\u003e46\u003c/strong\u003e(6), 1379-1392 (2017) https://doi.org/10.1177/1528083715619957.\u003c/li\u003e\n\u003cli\u003eZeng, Y., Gricius, Z., Weinell, C.E., Dam-Johansen, K., Ring, L., Kill, S.: Interactions between calcium carbonate and ammonium polyphosphate in low‐borate concentration hydrocarbon intumescent coatings. \u003cem\u003eFire. Mater.\u003c/em\u003e\u003cstrong\u003e46\u003c/strong\u003e(3), 499-512 (2022) https://doi.org/10.1002/fam.2994.\u003c/li\u003e\n\u003cli\u003eZuo, J., Liu, Z.H.: Controllable Synthesis, Characterization and Flame Retardant Properties of Three Kinds of \u0026alpha;-4CaO\u0026middot;5B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;7H\u003csub\u003e2\u003c/sub\u003eO Nanostructures Constructed by Nanoflakes. \u003cem\u003eActa. Chim. Sinica.\u003c/em\u003e\u003cstrong\u003e68\u003c/strong\u003e(24), 2535-2542 (2010)\u003c/li\u003e\n\u003cli\u003eMiao, J., Guo, R.F., Liu, Z.H.: Preparation of BaO\u0026middot;4B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;5H\u003csub\u003e2\u003c/sub\u003eO Nanomaterial and Evaluation of Its Flame Retardant Performance to PP by Thermal Decomposition Kinetics Method. \u003cem\u003eActa. Phys-Chim. Sin.\u003c/em\u003e\u003cstrong\u003e36\u003c/strong\u003e(6), 1905052 (2020) https://doi.org/10.3866/PKU.WHXB201905052 \u003c/li\u003e\n\u003cli\u003eZhang, L., Liu, Z.H.: Preparation of 2MgO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;1.5H\u003csub\u003e2\u003c/sub\u003eO nanomaterials and evaluation of their flame retardant properties by a thermal decomposition kinetic method. \u003cem\u003eJ. Therm. Anal. Calorim.\u003c/em\u003e\u003cstrong\u003e129\u003c/strong\u003e(2), 715-719 (2017 https://doi.org/10.1007/s10973-017-6288-2.\u003c/li\u003e\n\u003cli\u003eLiang, P., Liu, Z.H.: Controllable synthesis, growth mechanism and luminescence property of a novel monodisperse microsphere with a hole for Zn\u003csub\u003e8\u003c/sub\u003e[(BO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e(OH)\u003csub\u003e3\u003c/sub\u003e]:Eu\u003csup\u003e3+\u003c/sup\u003e. \u003cem\u003eCrystengcomm. \u003c/em\u003e\u003cstrong\u003e18\u003c/strong\u003e(8), 1311-1320 (2016) https://doi.org/10.1039/C5CE02018B.\u003c/li\u003e\n\u003cli\u003eLiu, J.P., Li, Y.Y., Huang, X.T., Li, Z.K., Li, G.Y., Zeng, H.B.: Hydrothermal synthesis of single-crystal szaibelyite MgBO\u003csub\u003e2\u003c/sub\u003e(OH) nanobeltas a new host material for red-emitting rare-earth ions. \u003cem\u003eChem. Mater.\u003c/em\u003e\u003cstrong\u003e20\u003c/strong\u003e(1), 250-257 (2008) https://doi.org/10.1021/cm702719s.\u003c/li\u003e\n\u003cli\u003eSun, P.P., Chen, L.Y., Xu, L., Zhu, W.C.: Hierarchical porous MgBO\u003csub\u003e2\u003c/sub\u003e(OH) microspheres: Hydrothermal synthesis, thermal decomposition, and application as adsorbents for Congo red removal. \u003cem\u003eChinese. J. Chem. Eng\u003c/em\u003e. \u003cstrong\u003e26\u003c/strong\u003e(07), 1561-1569 (2018) https://doi.org/10.1016/j.cjche.2018.01.013.\u003c/li\u003e\n\u003cli\u003eMa, Y.Q., Liu, Z.H.: Excellent adsorption performance for Congo red on hierarchical porous magnesium borate microsphere prepared by a template-free hydrothermal method. \u003cem\u003eJ. Taiwan. Inst. Chem. E\u003c/em\u003e. \u003cstrong\u003e86\u003c/strong\u003e, 92-100 (2018) https://doi.org/10.1016/j.jtice.2018.02.015.\u003c/li\u003e\n\u003cli\u003eZhang, Z.Q., Zhu, W.C., Wang, R.G., Zhang, L.L., Zhu, L., Zhang, Q.: Ionothermal confined self-organization for hierarchical porous magnesium borate superstructures as highly efficient adsorbents for dye removal. \u003cem\u003eJ. Mater. Chem. A.\u003c/em\u003e\u003cstrong\u003e2\u003c/strong\u003e(45), 19167-19179 (2014) https://doi.org/10.1039/C4TA03580A.\u003c/li\u003e\n\u003cli\u003eKonings, R.J.M., Cordfunke, E.H.P., Ouweltjes, W.: The standard enthalpy of formation of cesium monoborate: CsBO\u003csub\u003e2\u003c/sub\u003e. \u003cem\u003eJ. Chem. Thermodyn\u003c/em\u003e. \u003cstrong\u003e19\u003c/strong\u003e(2), 201-203 (1987) https://doi.org/10.1016/0021-9614(87)90112-1.\u003c/li\u003e\n\u003cli\u003eWang, J.F., Liang, P.: Thermochemical properties of alkaline-earth metals borates of a series of MB\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e11\u003c/sub\u003e(OH)\u003csub\u003e4\u003c/sub\u003e\u0026middot;xH\u003csub\u003e2\u003c/sub\u003eO (M=Ca, Sr, Ba; x=0, 3). \u003cem\u003eJ. Chem. Thermodyn\u003c/em\u003e. \u003cstrong\u003e134\u003c/strong\u003e, 1-4 (2019) https://doi.org/10.1016/j.jct.2019.02.030.\u003c/li\u003e\n\u003cli\u003eLiang, P., Li, S.Y.: Synthesis, characterization and standard molar enthalpies of formation of two zinc borates: 2ZnO\u0026middot;2B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO and ZnB\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e. \u003cem\u003eJ. Chem. Thermodyn\u003c/em\u003e. \u003cstrong\u003e139\u003c/strong\u003e(C), 105868 (2019) https://doi.org/10.1016/j.jct.2019.07.010.\u003c/li\u003e\n\u003cli\u003eLi, J., Li, B., Gao, S.Y.: Thermochemistry of hydrated lithium borates. \u003cem\u003eJ. Chem. Thermodyn.\u003c/em\u003e\u003cstrong\u003e30\u003c/strong\u003e(6), 681-688 (1998) https://doi.org/10.1006/jcht.1997.0324.\u003c/li\u003e\n\u003cli\u003eZhu, L.X., Yue, T., Gao, S.Y., Liu, Z.H., Xia, S.P.: Thermochemistry of rubidium calcium octaborate dodecahydrate. \u003cem\u003eThermochim. Acta\u003c/em\u003e. \u003cstrong\u003e402\u003c/strong\u003e(1), 241-245 (2003) https://doi.org/10.1016/S0040-6031(02)00539-7.\u003c/li\u003e\n\u003cli\u003eLi, J., Li, B., Gao, S.Y.: Thermochemistry of hydrated potassium and sodium borates. \u003cem\u003eJ. Chem. Thermodyn.\u003c/em\u003e\u003cstrong\u003e30\u003c/strong\u003e(4), 425-430 (1998) https://doi.org/10.1006/jcht.1997.0304.\u003c/li\u003e\n\u003cli\u003eLi, J., Gao, S.Y., Xia, S.P., Li, B., Hu, R.Z.: Thermochemistry of hydrated magnesium borates. \u003cem\u003eJ. Chem. Thermodyn.\u003c/em\u003e\u003cstrong\u003e29\u003c/strong\u003e(4), 491-497 (1997) https://doi.org/10.1006/jcht.1996.0183.\u003c/li\u003e\n\u003cli\u003eGuo, R.F., Ma, Y.Q., Liu, Z.H.: Three hierarchical porous magnesium borate microspheres: a serial preparation strategy, growth mechanism and excellent adsorption behavior for Congo red. \u003cem\u003eRsc. Adv\u003c/em\u003e. \u003cstrong\u003e9\u003c/strong\u003e(35), 20009-20018 (2019) https://doi.org/10.1039/C9RA03654G.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Li, P., Li, L.Q., Jia, Q.X.: Synthesis, characterization and thermochemistry of K\u003csub\u003e2\u003c/sub\u003eB\u003csub\u003e5\u003c/sub\u003eO\u003csub\u003e8\u003c/sub\u003e(OH)\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eThermochim. Acta\u003c/em\u003e. \u003cstrong\u003e454\u003c/strong\u003e(1), 23-25 (2007) https://doi.org/10.1016/j.tca.2006.12.008.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Zuo, C.F., Li, S.Y.: Synthesis and thermochemistry of 2CaO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eThermochim. Acta.\u003c/em\u003e\u003cstrong\u003e424\u003c/strong\u003e(1-2), 59-62 (2004) https://doi.org/10.1016/j.tca.2004.05.029.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Li, P., Zuo, C.F.: Standard Molar Enthalpies of Formation for the Two Hydrated Calcium Borates xCaO\u0026middot;5B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;yH\u003csub\u003e2\u003c/sub\u003eO (x=2 and 4, y=5 and 7). \u003cem\u003eJ. Chem. Eng. Data.\u003c/em\u003e\u003cstrong\u003e51\u003c/strong\u003e(1), 272-275 (2006) https://doi.org/10.1021/je050383m.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Wang, Y., Huang, H.S.: Determination of Standard Molar Enthalpies of Formation for the Two Barium Borates BaB\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026middot;xH\u003csub\u003e2\u003c/sub\u003eO (x=4, 0) by Microcalorimetry. \u003cem\u003eJ. Chem. Eng. Data\u003c/em\u003e. \u003cstrong\u003e52\u003c/strong\u003e(2), 487-490 (2007) https://doi.org/10.1021/je060422+.\u003c/li\u003e\n\u003cli\u003eHuang, H.S., Liu, Z.H.: Synthesis and thermochemistry of SrB\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026middot;2.5H\u003csub\u003e2\u003c/sub\u003eO and SrB\u003csub\u003e6\u003c/sub\u003eO\u003csub\u003e10\u003c/sub\u003e\u0026middot;5H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eThermochim. Acta\u003c/em\u003e. \u003cstrong\u003e463\u003c/strong\u003e(1-2), 87-89 (2007) https://doi.org/10.1016/j.tca.2007.07.010.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Hu, M.C.: Synthesis and thermochemistry of MgO\u0026middot;3B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;3.5H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eThermochim. Acta.\u003c/em\u003e\u003cstrong\u003e403\u003c/strong\u003e(2), 181\u0026ndash;184 (2003) https://doi.org/10.1016/S0040-6031(03)00058-3.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Hu, M.C.: Synthesis, characterization, and thermochemistry of a new form of 2MgO\u0026middot;3B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;17H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eThermochim. Acta.\u003c/em\u003e\u003cstrong\u003e414\u003c/strong\u003e(2), 215\u0026ndash;218 (2004) https://doi.org/10.1016/j.tca.2003.12.026.\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Zhao, U., Hu, M.C.: Synthesis, Characterization and Thermochemistry of 2MgO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;1.5H\u003csub\u003e2\u003c/sub\u003eO. \u003cem\u003eChinese. J. Chem\u003c/em\u003e. \u003cstrong\u003e21\u003c/strong\u003e(12), 1569-1572 (2010) https://doi.org/10.1002/cjoc.20030211211.\u003c/li\u003e\n\u003cli\u003eLiu, J., Ma, X.Y., Liu, Z.H.: Preparation of Ca[B\u003csub\u003e6\u003c/sub\u003eO\u003csub\u003e9\u003c/sub\u003e(OH)\u003csub\u003e2\u003c/sub\u003e]\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO nanomaterials by a phase transformation method and their flame retardant and thermodynamic properties. \u003cem\u003ePowder. Technol. \u003c/em\u003e\u003cstrong\u003e246\u003c/strong\u003e, 26\u0026ndash;30 (2013) https://doi.org/10.1016/j.powtec.2013.05.001.\u003c/li\u003e\n\u003cli\u003eGeng, Y.J., Liu, Z.H.: Preparation and thermodynamic characterization of 2CaO\u0026middot;B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO nanomaterials with enhanced flame retardant properties. \u003cem\u003eColloid. Surface. A\u003c/em\u003e. \u003cstrong\u003e522\u003c/strong\u003e(5), 563\u0026ndash;568 (2017) https://doi.org/10.1016/j.colsurfa.2017.03.044.\u003c/li\u003e\n\u003cli\u003eGuo, Y.W., Mao, L., Rong, F., Liu, Z.H.: Preparation of Zn\u003csub\u003e3\u003c/sub\u003eB\u003csub\u003e10\u003c/sub\u003eO\u003csub\u003e18\u003c/sub\u003e\u0026middot;14H\u003csub\u003e2\u003c/sub\u003eO nanomaterials and their thermochemical properties. \u003cem\u003eThermochim. Acta.\u003c/em\u003e\u003cstrong\u003e539\u003c/strong\u003e, 56\u0026ndash;61 (2012) https://doi.org/10.1016/j.tca.2012.04.007.\u003c/li\u003e\n\u003cli\u003eZhu, W.C., Zhang, X.Y., Zhang, Q., Xing, L.,Zhu, S.L.: Subunit contribution model for thermodynamic properties of borates and its application in hydrothermal synthesis of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) nanowhiskers. \u003cem\u003eCIESC Journal.\u003c/em\u003e\u003cstrong\u003e64\u003c/strong\u003e(2), 443-451 (2013) https://doi.org/10.3969/j.issn.0438-1157.2013.02.007\u003c/li\u003e\n\u003cli\u003eLiu, Z.H., Hu, M.C.: New synthetic method and thermochemistry of szaibelyite. \u003cem\u003eThermochim. Acta.\u003c/em\u003e\u003cstrong\u003e411\u003c/strong\u003e(1), 27-29 (2004) https://doi.org/10.1016/j.tca.2003.07.009.\u003c/li\u003e\n\u003cli\u003eYu, H.G., Liu, Y., Tan, Z.C., Dong, J.X., Zou, T.J., Huang, X.M., Qu, S.S.: A solution-reaction isoperibol calorimeter and standard molar enthalpies of formation of Ln (hq)2Ac(Ln= La, Pr), Thermochim. Acta. \u003cstrong\u003e401\u003c/strong\u003e(2), 217-224 (2003) https://doi.org/10.1016/S0040-6031(02)00566-X.\u003c/li\u003e\n\u003cli\u003eArcher, D.G.: Thermodynamic properties of the KCl+H\u003csub\u003e2\u003c/sub\u003eO system. \u003cem\u003eJ. Phys. Chem. Ref. Data.\u003c/em\u003e\u003cstrong\u003e28\u003c/strong\u003e(1), 1-17 (1999) https://doi.org/10.1063/1.556034.\u003c/li\u003e\n\u003cli\u003eRychl\u0026yacute;, R., Pek\u0026aacute;rek, V.: The use of potassium chloride and tris(hydroxymethyl)aminomethane as standard substances for solution calorimetry. \u003cem\u003eJ. Chem. Thermodyn.\u003c/em\u003e\u003cstrong\u003e9\u003c/strong\u003e(4), 391\u0026ndash;396 (1977) https://doi.org/10.1016/0021-9614(77)90060-X.\u003c/li\u003e\n\u003cli\u003eLi, J., Xia, S.P., Gao, S.Y.: FT-IR and Raman spectroscopic study of hydrated borates. \u003cem\u003eSpectrochim. Acta. A.\u003c/em\u003e\u003cstrong\u003e51\u003c/strong\u003e(4), 519-532 (1995) https://doi.org/10.1016/0584-8539(94)00183-C.\u003c/li\u003e\n\u003cli\u003eWagman, D.D., Evans, W.H., Parker, V.B.: The NBS tables of chemical thermodynamic properties. \u003cem\u003eJ. Phys. Chem. Ref. Data.\u003c/em\u003e\u003cstrong\u003e11\u003c/strong\u003e(Suppl. 2) (1982) https://doi.org/ 10.1063/1.555845.https://doi.org/ 10.1063/1.555845.\u003c/li\u003e\n\u003cli\u003eCox, J.D., Wagman, D.D., Medvedev, V.A.: CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989 https://api.semanticscholar.org/CorpusID:91473815.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Magnesium borate, Different morphologies, Standard molar enthalpy of formation, Solution calorimetry","lastPublishedDoi":"10.21203/rs.3.rs-4137398/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4137398/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMgBO\u003csub\u003e2\u003c/sub\u003e(OH) with flower-like, sea urchin-like, and rice panicle-like morphologies have been synthesized and characterized by XRD, FI-IR, SEM and TEM. The molar enthalpies of solution of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with different morphologies in 3.00 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq) were measured. With the incorporation of the previously determined enthalpy of solution of H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e in 3.00 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e HCl(aq), the enthalpy of solution of MgO in (HCl\u0026thinsp;+\u0026thinsp;H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e)(aq) and the standard molar enthalpies of formation of MgO(s), H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e(s) and H\u003csub\u003e2\u003c/sub\u003eO(l), the standard molar enthalpies of formation of MgBO\u003csub\u003e2\u003c/sub\u003e(OH) with flower-like, sea urchin-like, and rice panicle-like morphologies were calculated to be -(1465.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44), -(1464.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31) and \u0026minus;\u0026thinsp;(1476.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.46) kJ\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The results show that the morphology and crystal structure of the sample have an effect on its standard molar enthalpy of formation, and the crystal structure has a greater influence.\u003c/p\u003e","manuscriptTitle":"Synthesis and thermodynamic properties of nano magnesium borate MgBO 2 (OH) with three different morphologies","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-25 09:16:19","doi":"10.21203/rs.3.rs-4137398/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"77f27f11-d921-4703-9ba8-e6c91b63bd9d","owner":[],"postedDate":"March 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-31T20:59:29+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-25 09:16:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4137398","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4137398","identity":"rs-4137398","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}