{"paper_id":"4c447df8-77a9-4388-ac10-5ebfae9024b5","body_text":"Preparation of ZnGa2O4 Nanoflowers and Their Full-color Luminescence Properties | 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 Article Preparation of ZnGa2O4 Nanoflowers and Their Full-color Luminescence Properties Yan Liu, Xinhuan Wan, Tingting Zheng, Xiuyun Zhang, Chen Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2785059/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 Sep, 2023 Read the published version in Scientific Reports → Version 1 posted 8 You are reading this latest preprint version Abstract Gallate material, a luminescent matrix with excellent performance is normally prepared by vapor deposition or solid phase sintering method at high temperature, however, it has not been solved to prepare gallate-based fluorescent materials with full-color luminescent properties at low temperature. In this paper, ZnGa 2 O 4 undoped or doped with Cr or Mn nanoflowers composed of nanosheet-level structure were prepared by hydrothermal method at low temperature. Under ultraviolet light irradiation, ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ display three primary colors of blue, green and red luminescence through self-excitation, Mn 2+ and Cr 3+ excitation respectively. The solid fluorescence yields of blue, green, and red colors are 32.3, 36.5, and 40.7%, respectively. It is highly expected to be applied to color display, biological imaging, white light devices. Physical sciences/Materials science/Materials for optics Physical sciences/Materials science/Nanoscale materials Zinc Gallate Full Color Fluorescent Material Luminescence Property Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction In recent years, inorganic luminescent materials have attracted people's attention because of their wide applications in fluorescence imaging, color display, white Light Emitting Diodes (LEDs) and so on. 1 – 3 Therefore, constructing and designing efficient inorganic luminescent materials has become a hot topic for material scientists. Zinc gallate (ZnGa 2 O 4 ), a ternary spinel material with a band gap of 4.4–4.7 eV, has exhibited excellent potential in future display system due to its prominent blue emission, high chemical and thermal stability, and good cathodoluminescence characteristics at low-voltage. 4 , 5 Compared with other luminescent materials, zinc gallate can be self-excited by Ga-O group, and has blue light emission 6 , 7 . ZnGa 2 O 4 can also be used as the matrix of fluorescent materials, which has high luminous efficiency and narrow spectral band. The luminescent color can be changed by adjusting the surface properties 4 , 8 and composition of fluorescent materials, 9 , 10 or by doping the dopant activators. 11 , 12 Most fluorescent materials use rare earth metals as activators, such as Eu 3+ , Tb 3+ , Y 3+ , etc. 13 – 15 , but rare earth metals are expensive and lack of resources. Previous studies have shown that transition metal ions Mn 2+ and Cr 3+ can be used as activators of fluorescent materials, such as ZnGa 2 O 4 :Mn 2+ emitting green fluorescence and ZnGa 2 O 4 :Cr 3+ emitting red fluorescence. 11 , 16 , 17 Various synthetic methods have been adopted to synthesize these fluorescent materials, such as thermal evaporation 18 , solid-state reaction method 19 , Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD) and so on. 20 These synthetic methods usually require high reaction temperature, which is over 900°C, so the energy consumption is high, which brings hidden dangers to environmental pollution control. Therefore, it is an urgent problem to find a low-temperature synthesis method for energy saving and emission reduction in the field of synthesis of full-color luminescent materials. In this paper, undoped (ZnGa 2 O 4 ), Mn 2+ -doped (ZnGa 2 O 4 :Mn 2+ ) and Cr 3+ -doped (ZnGa 2 O 4 :Cr 3+ ) nano-luminescent materials have been synthesized at low temperature by one step hydrothermal method under the template action of ethylenediamine. These luminescent materials are composed of 5 µm -sized nano-flowers, each of which is composed of 6–10 nm nanoflake hierarchical structure. Under ultraviolet irradiation, ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ display three primary colors of blue, green and red through self-excitation, Mn 2+ excitation and Cr 3+ ion excitation, respectively. Methods Raw materials and reagents Gallium nitrate hydrate (Ga(NO 3 ) 3 ·xH 2 O), Zinc acetate dihydrate (Zn(CH 3 COO) 2 ·2H 2 O), Manganese acetate tetrahydrate (Mn(CH 3 COO) 2 ·4H 2 O), Chromium nitrate nonahydrate (Cr(NO 3 ) 3 ·9H 2 O), and Anhydrous ethylenediamine (NH 2 (CH 2 ) 2 NH 2 ) are analytically pure and boughten from Sigma-Aldrich Shanghai trading Co., Ltd.. Anhydrous ethanol (CH 3 CH 2 OH), ≥ 99.9% are boughten from Shanghai Sinopharm Chemical Co., Ltd.. All reagents were not further treated before use. Water used in the experiment is Milli-Q ultrapure water. Sample preparation Synthesis of ZnGa 2 O 4 Ga(NO 3 ) 3 ·xH 2 O 0.512g (2mmol) and Zn(CH 3 COO) 2 ·2H 2 O 0.220g (1mmol) are added into 20 mL deionized water, magnetically stirred for 20 min at room temperature. And then 10 mL anhydrous ethylenediamine is added into the above solution, with continue stirring for 20 min. The mixed solution is transferred to a 50 mL reaction kettle and placed into an oven, and stirred at 220°C for 12 h. The white precipitate was obtained by washed with water and absolute ethanol several times, and dried at 60°C for 12 h. Synthesis of ZnGa 2 O 4 : Mn 2+ : Ga(NO 3 ) 3 ·xH 2 O 0.512g (2mmol) and Zn(CH 3 COO) 2 ·2H 2 O 0.220g (1mmol) are added into 17.5 mL deionized water, magnetically stirred for 20 min at room temperature. And then 2.5 mL Mn(CH 3 COO) 2 solution with a concentration of 4 mmol L − 1 is added to above solution so that the concentration of Mn 2+ is 1% of that of Zn 2+ , and magnetically stirred at room temperature for 20 min. Next, 10 mL anhydrous ethylenediamine is added into the above solution, with continue stirring for 20 min. The mixed solution is transferred to a 50 mL reaction kettle and placed into an oven, and stirred at 220°C for 12 h. The white precipitate was obtained by washed with water and absolute ethanol several times, and dried at 60°C for 12 h. Synthesis of ZnGa 2 O 4 : Cr 3+ : The method is as same as the preparation of ZnGa 2 O 4 :Mn 2+ , and finally the concentration of Cr 3+ is 0.5% of that of Zn 2+ . Sample characterization The phase structure of the sample was determined at room temperature by X-ray powder diffraction analyzer (Rigaku D/Max 2200PC, graphite monochromator filter, Cu Kα radiation, λ = 0.1542 nm) with the condition of tube voltage 40 kV, the tube current 20 mA, the scanning range 10–80° (2θ) and the scanning speed 10 min − 1 . The morphology and microstructure of the product were characterized by transmission electron microscope (JEM-100CXII, accelerating voltage 80 kV), high resolution transmission electron microscope (Philips Tecnai 20U-TWIN, accelerating voltage 200 kV) and scanning electron microscope (FE-SEM, S-4800, Hitachi, accelerating voltage 5 kV). X-ray photoelectron spectrometer (PHI-5300 ESCA spectrometer, Perkin Elmer, Al Kα as excitation light source) was used to analyze the surface properties of the samples. Before the spectrogram analysis, the electron binding energies of all elements were corrected with the C 1s peak at 284.6 eV as reference. Room temperature fluorescence spectrum (PL) and fluorescence lifetime of samples were measured by Agilent Cary Eclipse Fluorescence Spectrometer. The UV-VIS absorption spectrum of the sample at room temperature was tested by Agilent Cary Series UV-VIS spectrometer, and BaSO 4 was used as baseline correction before the test. The infrared spectrum of the sample was tested by NICOLET FT-IR spectrometer, and the KBr was used as the background. Results and Discussion Phase Structure and Morphology Characteristics ZnGa 2 O 4 is a bimetallic oxide composed of ZnO and Ga 2 O 3 , with Fd-3m space group symmetry, a = b = c = 8.335, and spinel structure with chemical formula AB 2 O 4 , in which Zn 2+ occupying tetrahedral center, Ga 3+ occupying octahedral center, 21 as shown in Fig. 1 (a). Usually, the charge imbalance caused by the introduction of impurity ions is unfavorable to the luminous intensity of luminophores, so higher energy is needed to eliminate the charge imbalance, such as calcination at high temperature for a long time. 22 The effective compensation factor φ when ions are substituted was calculated according to the formula φ = Z/r , in which Z is the charge number of ions and r is the effective radius of ions. 23 The greater the difference of φ , the more difficult it is to substitute ions. As shown in Table S1 , for hexa-coordinate substitution of Mn 2+ , the effective compensation factor φ is 2.41, which is much lower than that of Ga 3+ 4.83, so it is difficult for Mn 2+ to replace Ga 3+ , while easy to replace Zn 2+ due to the small difference of effective compensation factor. 11 , 17 Therefore, in the substitution reaction of ZnGa 2 O 4 , ions with similar effective radii are easy to be substituted with each other, that is, Mn 2+ replaces Zn 2+ to produce four coordinate substitutions, and Cr 3+ replaces Ga 3+ to produce six coordinate substitution. 17 , 24 The SEM photos of the three nanomaterials (ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ ) with different magnification is shown in Fig. 1 (b)-(g) . They all present a flower-like nanostructure of about 5µm, which is composed of multiple nanosheet-level substructures with a thickness of 6–10 nm interspersed together. The difference between the three samples is that the nanosheets composed of ZnGa 2 O 4 are thicker and the degree of curling of the nanosheets is smaller, while the nanosheets doped with Mn 2+ and Cr 3+ are thinner, and the nanosheets are freely curled to form spherical nanoflowers. As shown in Figure S1 . Zn, Ga, O and the corresponding doped elements Mn and Cr are uniformly distributed in the flower-like nanostructures confirmed by the element distribution surface scans. The flower-like structure of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ can also be seen from the TEM photos in Fig. 1 (h)-(j) . Each flower is composed of the sub-structure of nano-flakes, and the size of nano-flowers is about 5 µm. From the contrast of the electron microscope photos, it can be clearly seen that the nano-flakes constituting the flower-like structure become thinner in turn, which is similar to that of Scanning electron microscope (SEM). The phenomenon may be due to the impurity ions adsorbed on the initial grain surface during hydrothermal process, which inhibiting the crystallization of the material to some extent, preventing the grain growth in some directions, and resulting in the formation of thinner nanosheets. High-resolution photos and corresponding selective electron diffraction photos of ZnGa 2 O 4 are shown in Fig. 1 (k) . The lattice spacing 0.44nm is corresponding to the (200) crystal plane of ZnGa 2 O 4 , and the selective electron diffraction photo clearly shows single crystal structure of a ZnGa 2 O 4 nanoflake. In the single crystal structure of the sheet, the diffraction points correspond to (200) and (111) crystal plane. The direction of the crystal zone axis is confirmed to [011] by calculating, therefore the exposed surface of the nanoplate is (110) plane. As shown in Fig. 2 (a) the diffraction peaks of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ all correspond to the diffraction peaks of standard card JCPDS38-1240 ZnGa 2 O 4 , which are cubic spinel structure. After doping Mn 2+ and Cr 3+ , the intensity of the diffraction peak decreases, and the corresponding FWHM(full width at half maximum) increases in sequence. The results of X-ray diffractometer (XRD) analysis also indicate that the secondary structure nanosheets that make up the nanoflowers become thinner in turn after doping Mn 2+ and Cr 3+ , which consistent precisely with the observation results of SEM and transmission electron microscopy (TEM). As shown in Fig. 2 (b)-(e) the electron binding energies of 2p 1/2 orbitals and 2p 3/2 orbitals of Ga are located at 1143.6 eV and 1116.8 eV, respectively. And the electron binding energies of 2p 1/2 orbitals and 2p 3/2 orbitals of Zn are located at 1043.8 eV and 1021.1 eV, respectively. The characteristic peaks of electron binding energies located at 654.4 eV and 645.5 eV belong to 2p 1/2 orbitals and 2p 3/2 orbitals of Mn, respectively and manganese ions show + 2 valences. The characteristic peaks of electron binding energy at 586.5eV and 576.5eV respectively belong to 2p 1/2 orbitals and 2p 3/2 orbitals of Cr and chromium ions show + 3 valences. The intensity of these characteristic peaks is small due to the low contents of Mn and Cr. Infrared and ultraviolet spectral characteristics In order to understand the chemical composition of the sample, the Fourier transform infrared spectrum is conducted. The Fourier Transform infrared spectroscopy (FT-IR) of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 : Cr 3+ in Figure S2 also indicate the the samples were binary metal oxides consisting of Zn-O and Ga-O groups. As showed in Figure S2 , the broad absorption peak at the 3445cm - 1 wavelength belongs to the stretching vibration of O-H and N-H. The stretching vibration of N-H may come from the residual ethylenediamine in the sample, but there is no obvious stretching vibration peak of it near 1190cm - 1 . Therefore, the residual ethylenediamine may be very small and can be ignored after repeated cleaning of water and anhydrous ethanol. In the fingerprint region at low wavelength, the larger peaks of 585cm - 1 and 425cm - 1 are attributed to the vibration absorption of Zn-O and Ga-O, respectively. Through the infrared spectrum analysis, no other vibration peaks are observed except Zn-O and Ga-O in the sample, so it is determined that the sample is a binary metal oxide composed of Zn-O group and Ga-O group. The UV-vis absorption spectra of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ samples are shown in Figure S3 . It can be seen from the figure that the absorption regions of the three samples are basically the same, and there is only absorption in the region smaller than 350nm. It is also confirmed that ZnGa 2 O 4 can only be excited at wavelengths less than 350nm. However, in the 300-350nm wavelength region, compared with the absorption peak of ZnGa 2 O 4 , the absorption of ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ increases slightly, which may be due to the absorption of a small amount of Mn and Cr itself, because the amount of Mn 2+ and Cr 3+ is very small, only 0.4% and 1%, so the absorption of these two elements is also very weak. Luminescent properties The excitation and emission spectra of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ are shown in Fig. 3 (a)-(c) . For undoped ZnGa 2 O 4 , three peaks can be seen in the excitation spectrum, which are located at 226 nm 239 nm and 257 nm, respectively. These excitation peaks are caused by the charge transfer from O 2 - to octahedral center Ga 3+ and the ultraviolet absorption of ZnGa 2 O 4 itself. 25 The emission spectrum obtained using226nm as the excitation wavelength is a broad peak with the highest peak of 456nm in the range of 340-750nm. This broad emission peak is in all probability caused by the self-excitation of Ga- O hexahedron in the spinel structure. The luminescent properties of fluorescent host materials are usually changed by introducing impurity ions 26 , that is also applicable to ZnGa 2 O 4 host materials. Mn 2+ -doped ZnGa 2 O 4 has green fluorescence emission, as shown in Fig. 3 (b) , Except for the charge transfer from O 2 - to Ga 3+ in the octahedral center and the ultraviolet absorption of ZnGa 2 O 4 itself, the absorption of Mn 2+ excites a red shift of 32 near 300nm, which is consistent with the analysis of ultraviolet-visible absorption spectrum in Figure S3 . Due to the activation of Mn 2+ , the emission spectrum with the highest emission peak of 505 nm is located in the range of 470–600 nm with the excitation wavelength of 226 nm. After enlarged locally as shown in Figure S4 , the five smaller excitation peaks located between 351-443nm and centered at 351nm, 379nm, 410nm, 422nm and 443nm respectively correspond to 5 A 1 - 4 E, 6 A 1 - 4 T 2 , 6 A 1 - 4 A 1 , 4 E 1 and 6 A 1 - 4 T of Mn 2+ . 27 When excited at 226nm, ZnGa 2 O 4 :Mn 2+ has green emission at 505nm, which belongs to the 4 T 1 - 6 A 1 d orbital electron forbidden transition of Mn 2+ . 11,17 This is the process of energy transfer from ZnGa 2 O 4 matrix to Mn 2+ . 27 The transition process of 4 T 1 - 6 A 1 of Mn 2+ is accompanied by strong 3d shell lattice vibration coupling, and is affected by crystal field and symmetric sites. If Mn 2+ is in a weak crystal field, i.e. tetrahedron, the splitting of excitation energy will be weak, which will be accompanied by high energy emission, that is, green light and if Mn 2+ is in a strong crystal field, i.e., octahedron, it will emit yellow or red light, 17 , 27 which is consistent with our previous analysis of crystal structure. In our investigation, Mn 2+ replaces Zn 2+ with similar ionic radius in cubic ZnGa 2 O 4 matrix to generate tetrahedral coordination and emit green light, which is completely consistent with the test results of fluorescence spectrum. The excitation and emission spectra of ZnGa 2 O 4 :Cr 3+ are shown in Figs. 3 (c) . There is a wide excitation peak between 200–350 nm, including four intensity excitation peaks (226 nm, 240 nm, 257 nm, 266 nm), which related to the charge transfer transition of O 2− to the octahedral center Ga 3+ and the absorption transition with the belt, and the excitation spectrum of 300–350 nm is caused by the absorption of Cr 3+ . A red emission peak at 696 nm was obtained by excitation at 226 nm, which was attributed to the 2 E- 4 A 2 characteristic transformation of Cr 3+ . 28 Meanwhile, a similar red emission peak at 696 nm was obtained by excitation at 416 nm and 572 nm. These two excitation peaks at 416 nm and 572 nm are caused by d-d electron-electron transitions of Cr 3+ , 24 , 29 corresponding to the 4 A 2 - 4 T 1 and 4 A 2 - 4 T 2 characteristic transitions of Cr 3+ , respectively. 30 Undoped, Mn 2+ doped and Cr 3+ doped ZnGa 2 O 4 have blue, green and red emission properties under ultraviolet (UV) excitation, respectively. The excitation wavelengths used in the emission spectra of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ are all 226nm, indicating that the hetero ions in ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ can effectively enter the lattice of ZnGa 2 O 4 under hydrothermal conditions to replace Zn 2+ and Ga 3+ to form tetrahedral and octahedral coordination, respectively. This is related to the addition of an appropriate amount of ethylenediamine during hydrothermal. Ethylenediamine aqueous solution is a strongly alkaline solution, which plays an effective role in promoting the crystallization of materials and the entry of hetero ions into the crystal lattice of the matrix under the condition of hydrothermal high temperature and high pressure. We also conduct experiment keeping other conditions remaining the same without ethylenediamine in the synthesis. The obtained ZnGa 2 O 4 doped with Mn 2+ and Cr 3+ does not show green and red emission properties after UV excitation, indicating that it is difficult for hydrothermal hetero ions to enter into the lattice of ZnGa 2 O 4 matrix under the condition of non-strong alkaline solvent. The fluorescence attenuation curves of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ are fitted exponentially as shown in Fig. 3 (d) . The attenuation curves of the three samples are all fitted by double exponents, which are in accordance with the formula. I = I 1 exp(- t / τ 1 ) + I 2 exp(- t / τ 2 ) (1) Where I is the fluorescence intensity when the time is t , I 1 and I 2 are fitting constants, and τ 1 and τ 2 are fluorescence lifetime. After fitting, each sample corresponds to two millisecond lifetimes, a shorter lifetime τ 1 and a relatively longer life τ 2 . The specific fitting parameters are shown in Table S2 . The longer lifetimes of each sample of ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ correspond to the self-excitation of Ga-O in the bulk phase of luminescent materials, the 4 T 1 - 6 A 1 transition of Mn 2+ and the 2 E- 4 A 2 transition of Cr 3+ , respectively. The short lifetime of the three samples is due to the fact that the surface effect of the materials has a great influence on the luminescence lifetime. These materials are all composed of ultra-thin 6–10 nm nanosheets with large surface area, and the increase of surface atoms leads to the appearance of more activated ions on the surface of the nanosheets. However, the impurities, unsaturated bonds, vacancies and other surface defects on the surface of the nanoparticles will quenched the activated ions and lead to radiation-free transition, thus shortening the life of the activated ions. 8 Excited by 254nm's handheld UV lamp, ZnGa 2 O 4 , ZnGa 2 O 4 :Mn 2+ and ZnGa 2 O 4 :Cr 3+ appear bright blue, green and red, respectively. Their optical photos are shown in Fig. 4 (a) . The solid fluorescence yields of blue, green, and red colors are 32.3, 36.5, and 40.7%, respectively. Under the light excitation of 226nm wavelength, the fluorescence emission spectra of the three materials are shown in Fig. 4 (b) . The maximum fluorescence emission spectra of the three materials are located in 456nm, 505nm and 696nm, respectively, which basically correspond to the central regions of blue, green and red. Their emission spectra are imported into the CIE color coordinate software, respectively, and the color coordinate diagram shown in Fig. 4 (c) is obtained. The color coordinates are located at (0.19, 0.23), (0.10, 0.65) and (0.66, 0.34), respectively, which indicates that any color including white in the triangular area connected by the three points can be obtained by changing the ratio of the three luminescent materials. Conclusions ZnGa 2 O 4 nanoflowers with single size composed of ZnGa 2 O 4 flake substructures with a thickness of 6-10nm were synthesized by a simple hydrothermal method under the action of ethylenediamine template. The luminescence color of ZnGa 2 O 4 is controlled by doping Mn 2+ and Cr 3+ . Under UV excitation, undoped ZnGa 2 O 4 , ZnGa 2 O 4 doped with Mn 2+ and Cr 3+ have blue, green and red emission properties, respectively. The luminescence properties of the same matrix material with three primary colors are obtained. The blue, green and red fluorescence comes from the self-excited electron transfer of Ga-O itself and the 3d electron energy transfer of Mn 2+ and Cr 3+ . These ZnGa 2 O 4 -based fluorescent nanomaterials are expected to be used in color display, biological imaging and white light devices. Declarations Acknowledgement Thanks for the support of the Experimental Center of Shandong University of Traditional Chinese Medicine and the Natural Science Foundation of Shandong Province (Grant No.: ZR2020 MB108, ZR2021QH232). Author contributions statement Yan Liu: Conceptualization, methodology, formal analysis, investigation, writing—original draft, writing—review and editing, Xinhuan Wan: conceptualization, methodology, invisualization, writing review & editing, Funding acquisition. Tingting Zheng: conceptualization, data curation, formal analysis, funding acquisition, methodology, supervision, writing-original draft, writing-review & editing. 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Full Color Emission in ZnGa 2 O 4 : Simultaneous Control of the Spherical Morphology, Luminescent, and Electric Properties via Hydrothermal Approach. Advanced Functional Materials 24, 6581–6593, doi: 10.1002/adfm.201402092 (2014). Additional Declarations No competing interests reported. Supplementary Files rawdate.zip SupportingInformation.docx Cite Share Download PDF Status: Published Journal Publication published 02 Sep, 2023 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Major revision 01 Jun, 2023 Reviews received at journal 24 May, 2023 Reviewers agreed at journal 18 May, 2023 Reviewers invited by journal 18 May, 2023 Editor assigned by journal 18 May, 2023 Editor invited by journal 26 Apr, 2023 Submission checks completed at journal 26 Apr, 2023 First submitted to journal 06 Apr, 2023 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. 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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-2785059\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":195331696,\"identity\":\"b771fe04-4f8f-4159-9f99-dc436f25bee1\",\"order_by\":0,\"name\":\"Yan Liu\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Shandong University of Traditional Chinese Medicine\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Yan\",\"middleName\":\"\",\"lastName\":\"Liu\",\"suffix\":\"\"},{\"id\":195331697,\"identity\":\"bd31f945-cb64-4760-9c81-11c15014899a\",\"order_by\":1,\"name\":\"Xinhuan Wan\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Shandong University of Traditional Chinese Medicine\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Xinhuan\",\"middleName\":\"\",\"lastName\":\"Wan\",\"suffix\":\"\"},{\"id\":195331699,\"identity\":\"4f8e2b1c-3f25-45e8-a681-0f338ffe460e\",\"order_by\":2,\"name\":\"Tingting Zheng\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtUlEQVRIiWNgGAWjYJCCAwkMEjz8zMyHHxClnIeNgfHABwYLOcl2tjQDYrUwH5zBUGFscJ5HQYIoLfby7Q8O8zBIJG4GkgYMNTbRxNiSANay7TDvgQcMx9JyG4jQcgCqhS/BgLHhMDFagMrADmvmMZAgUgszA9D7EsYGzERrOZbGAAxkCTmJw8BATiDGL+zNxx9/SGCo4+HvP3z4wYcaG8JawIDxH5SRQJTyUTAKRsEoGAUEAQDaGjj2FeNO1gAAAABJRU5ErkJggg==\",\"orcid\":\"\",\"institution\":\"Shandong University of Traditional Chinese Medicine\",\"correspondingAuthor\":true,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Tingting\",\"middleName\":\"\",\"lastName\":\"Zheng\",\"suffix\":\"\"},{\"id\":195331700,\"identity\":\"54e6c7d5-4bd0-4875-96cf-da02a4c84fa8\",\"order_by\":3,\"name\":\"Xiuyun Zhang\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Shandong University of Traditional Chinese Medicine\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Xiuyun\",\"middleName\":\"\",\"lastName\":\"Zhang\",\"suffix\":\"\"},{\"id\":195331703,\"identity\":\"cf33dea1-9835-41cf-a98e-6416c02ea5e1\",\"order_by\":4,\"name\":\"Chen Chen\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Shandong University of Traditional Chinese Medicine\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Chen\",\"middleName\":\"\",\"lastName\":\"Chen\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2023-04-06 09:45:50\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-2785059/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-2785059/v1\",\"draftVersion\":[],\"editorialEvents\":[{\"content\":\"https://doi.org/10.1038/s41598-023-41658-5\",\"type\":\"published\",\"date\":\"2023-09-02T15:08:58+00:00\"}],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":36445354,\"identity\":\"a4b9df06-34dd-44f2-82b2-59939239bc15\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:37:08\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":182359,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(a) Cubic spinel structure of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, SEM images of (b)-(c) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, (d)-(e) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and (f)-(g) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, TEM images of (h) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, (i) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, (j) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e (k) HRTEM image of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, with the inset showing the corresponding SAED patterns.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/dfb515b20ff23b138fe63526.png\"},{\"id\":36445808,\"identity\":\"529783ec-1fdb-424b-a258-08ba24efdb01\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:53:08\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":93467,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(a)XRD patterns of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e. The XPS spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e: Cr\\u003csup\\u003e3+\\u003c/sup\\u003e: (b) Zn 2p, (c) Ga 2p, (d) Mn 2p in ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and (e)Cr 2p in ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/a103c3f339c95046419b3191.png\"},{\"id\":36445352,\"identity\":\"28f74da4-c556-4fb7-8dc2-fed49b99ce0c\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:37:08\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":92492,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eExcitation and emission spectra of (a) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, (b) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, (c) ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e and (d) photoluminescence decay curves and bi-exponential fittings for the ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e: Cr\\u003csup\\u003e3+\\u003c/sup\\u003e.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/edbb6d1d6e79175dbfb96bb7.png\"},{\"id\":36445603,\"identity\":\"9972deca-1113-4577-9f20-30bd6c80e80b\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:45:08\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":97489,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(a) Digital images of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e on glass substrates under UV light excitation. (b) PL emission spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e samples. (c) The CIE chromaticity diagram for ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (0.19, 0.23), ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e (0.10, 0.65), and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e (0.66, 0.34) samples.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/a36d29ddaa12a38946af0006.png\"},{\"id\":42781906,\"identity\":\"01d9a342-3134-49e5-9df2-e1c330871152\",\"added_by\":\"auto\",\"created_at\":\"2023-09-07 15:14:15\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":750541,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/140e9012-e5b9-4646-af70-5f166029d5af.pdf\"},{\"id\":36445357,\"identity\":\"d533091d-c535-4853-afda-a9d8734c848b\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:37:09\",\"extension\":\"zip\",\"order_by\":1,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":64331182,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"rawdate.zip\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/d4a3b07311dd14bad55ff5b5.zip\"},{\"id\":36445356,\"identity\":\"256a00e8-c154-4860-ab2a-eb974a075e81\",\"added_by\":\"auto\",\"created_at\":\"2023-04-28 19:37:08\",\"extension\":\"docx\",\"order_by\":2,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":1643103,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"SupportingInformation.docx\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2785059/v1/bcf95bbe2d428d8f0c21a25e.docx\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Preparation of ZnGa2O4 Nanoflowers and Their Full-color Luminescence Properties\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eIn recent years, inorganic luminescent materials have attracted people's attention because of their wide applications in fluorescence imaging, color display, white Light Emitting Diodes (LEDs) and so on.\\u003csup\\u003e\\u003cspan additionalcitationids=\\\"CR2\\\" citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e\\u003c/sup\\u003e Therefore, constructing and designing efficient inorganic luminescent materials has become a hot topic for material scientists. Zinc gallate (ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e), a ternary spinel material with a band gap of 4.4\\u0026ndash;4.7 eV, has exhibited excellent potential in future display system due to its prominent blue emission, high chemical and thermal stability, and good cathodoluminescence characteristics at low-voltage.\\u003csup\\u003e\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e\\u003c/sup\\u003e Compared with other luminescent materials, zinc gallate can be self-excited by Ga-O group, and has blue light emission\\u003csup\\u003e\\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e\\u003c/sup\\u003e. ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e can also be used as the matrix of fluorescent materials, which has high luminous efficiency and narrow spectral band. The luminescent color can be changed by adjusting the surface properties\\u003csup\\u003e\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e\\u003c/sup\\u003e and composition of fluorescent materials,\\u003csup\\u003e\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e\\u003c/sup\\u003e or by doping the dopant activators.\\u003csup\\u003e\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e12\\u003c/span\\u003e\\u003c/sup\\u003e Most fluorescent materials use rare earth metals as activators, such as Eu\\u003csup\\u003e3+\\u003c/sup\\u003e, Tb\\u003csup\\u003e3+\\u003c/sup\\u003e, Y\\u003csup\\u003e3+\\u003c/sup\\u003e, etc.\\u003csup\\u003e\\u003cspan additionalcitationids=\\\"CR14\\\" citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e13\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e\\u003c/sup\\u003e, but rare earth metals are expensive and lack of resources. Previous studies have shown that transition metal ions Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e can be used as activators of fluorescent materials, such as ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e emitting green fluorescence and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e emitting red fluorescence.\\u003csup\\u003e\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e16\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e\\u003c/sup\\u003e Various synthetic methods have been adopted to synthesize these fluorescent materials, such as thermal evaporation\\u003csup\\u003e\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e\\u003c/sup\\u003e, solid-state reaction method\\u003csup\\u003e\\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e\\u003c/sup\\u003e, Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD) and so on.\\u003csup\\u003e\\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e20\\u003c/span\\u003e\\u003c/sup\\u003e These synthetic methods usually require high reaction temperature, which is over 900\\u0026deg;C, so the energy consumption is high, which brings hidden dangers to environmental pollution control. Therefore, it is an urgent problem to find a low-temperature synthesis method for energy saving and emission reduction in the field of synthesis of full-color luminescent materials.\\u003c/p\\u003e \\u003cp\\u003eIn this paper, undoped (ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e), Mn\\u003csup\\u003e2+\\u003c/sup\\u003e-doped (ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e) and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e-doped (ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e) nano-luminescent materials have been synthesized at low temperature by one step hydrothermal method under the template action of ethylenediamine. These luminescent materials are composed of 5 \\u0026micro;m -sized nano-flowers, each of which is composed of 6\\u0026ndash;10 nm nanoflake hierarchical structure. Under ultraviolet irradiation, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e display three primary colors of blue, green and red through self-excitation, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e excitation and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e ion excitation, respectively.\\u003c/p\\u003e\"},{\"header\":\"Methods\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eRaw materials and reagents\\u003c/h2\\u003e \\u003cp\\u003eGallium nitrate hydrate (Ga(NO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e\\u0026middot;xH\\u003csub\\u003e2\\u003c/sub\\u003eO), Zinc acetate dihydrate (Zn(CH\\u003csub\\u003e3\\u003c/sub\\u003eCOO)\\u003csub\\u003e2\\u003c/sub\\u003e\\u0026middot;2H\\u003csub\\u003e2\\u003c/sub\\u003eO), Manganese acetate tetrahydrate (Mn(CH\\u003csub\\u003e3\\u003c/sub\\u003eCOO)\\u003csub\\u003e2\\u003c/sub\\u003e\\u0026middot;4H\\u003csub\\u003e2\\u003c/sub\\u003eO), Chromium nitrate nonahydrate (Cr(NO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e\\u0026middot;9H\\u003csub\\u003e2\\u003c/sub\\u003eO), and Anhydrous ethylenediamine (NH\\u003csub\\u003e2\\u003c/sub\\u003e(CH\\u003csub\\u003e2\\u003c/sub\\u003e)\\u003csub\\u003e2\\u003c/sub\\u003eNH\\u003csub\\u003e2\\u003c/sub\\u003e) are analytically pure and boughten from Sigma-Aldrich Shanghai trading Co., Ltd.. Anhydrous ethanol (CH\\u003csub\\u003e3\\u003c/sub\\u003eCH\\u003csub\\u003e2\\u003c/sub\\u003eOH), \\u0026ge;\\u0026thinsp;99.9% are boughten from Shanghai Sinopharm Chemical Co., Ltd.. All reagents were not further treated before use. Water used in the experiment is Milli-Q ultrapure water.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec4\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eSample preparation\\u003c/h2\\u003e \\u003cp\\u003e \\u003cstrong\\u003eSynthesis of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e\\u003c/strong\\u003e \\u003cp\\u003eGa(NO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e\\u0026middot;xH\\u003csub\\u003e2\\u003c/sub\\u003eO 0.512g (2mmol) and Zn(CH\\u003csub\\u003e3\\u003c/sub\\u003eCOO)\\u003csub\\u003e2\\u003c/sub\\u003e\\u0026middot;2H\\u003csub\\u003e2\\u003c/sub\\u003eO 0.220g (1mmol) are added into 20 mL deionized water, magnetically stirred for 20 min at room temperature. And then 10 mL anhydrous ethylenediamine is added into the above solution, with continue stirring for 20 min. The mixed solution is transferred to a 50 mL reaction kettle and placed into an oven, and stirred at 220\\u0026deg;C for 12 h. The white precipitate was obtained by washed with water and absolute ethanol several times, and dried at 60\\u0026deg;C for 12 h.\\u003c/p\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eSynthesis of ZnGa\\u003c/b\\u003e \\u003csub\\u003e \\u003cb\\u003e2\\u003c/b\\u003e \\u003c/sub\\u003e \\u003cb\\u003eO\\u003c/b\\u003e \\u003csub\\u003e \\u003cb\\u003e4\\u003c/b\\u003e \\u003c/sub\\u003e:\\u003cb\\u003eMn\\u003c/b\\u003e\\u003csup\\u003e\\u003cb\\u003e2+\\u003c/b\\u003e\\u003c/sup\\u003e: Ga(NO\\u003csub\\u003e3\\u003c/sub\\u003e)\\u003csub\\u003e3\\u003c/sub\\u003e\\u0026middot;xH\\u003csub\\u003e2\\u003c/sub\\u003eO 0.512g (2mmol) and Zn(CH\\u003csub\\u003e3\\u003c/sub\\u003eCOO)\\u003csub\\u003e2\\u003c/sub\\u003e\\u0026middot;2H\\u003csub\\u003e2\\u003c/sub\\u003eO 0.220g (1mmol) are added into 17.5 mL deionized water, magnetically stirred for 20 min at room temperature. And then 2.5 mL Mn(CH\\u003csub\\u003e3\\u003c/sub\\u003eCOO)\\u003csub\\u003e2\\u003c/sub\\u003e solution with a concentration of 4 mmol L\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e is added to above solution so that the concentration of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e is 1% of that of Zn\\u003csup\\u003e2+\\u003c/sup\\u003e, and magnetically stirred at room temperature for 20 min. Next, 10 mL anhydrous ethylenediamine is added into the above solution, with continue stirring for 20 min. The mixed solution is transferred to a 50 mL reaction kettle and placed into an oven, and stirred at 220\\u0026deg;C for 12 h. The white precipitate was obtained by washed with water and absolute ethanol several times, and dried at 60\\u0026deg;C for 12 h.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eSynthesis of ZnGa\\u003c/b\\u003e \\u003csub\\u003e \\u003cb\\u003e2\\u003c/b\\u003e \\u003c/sub\\u003e \\u003cb\\u003eO\\u003c/b\\u003e \\u003csub\\u003e \\u003cb\\u003e4\\u003c/b\\u003e \\u003c/sub\\u003e:\\u003cb\\u003eCr\\u003c/b\\u003e\\u003csup\\u003e\\u003cb\\u003e3+\\u003c/b\\u003e\\u003c/sup\\u003e: The method is as same as the preparation of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, and finally the concentration of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e is 0.5% of that of Zn\\u003csup\\u003e2+\\u003c/sup\\u003e.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec5\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eSample characterization\\u003c/h2\\u003e \\u003cp\\u003eThe phase structure of the sample was determined at room temperature by X-ray powder diffraction analyzer (Rigaku D/Max 2200PC, graphite monochromator filter, Cu Kα radiation, λ\\u0026thinsp;=\\u0026thinsp;0.1542 nm) with the condition of tube voltage 40 kV, the tube current 20 mA, the scanning range 10\\u0026ndash;80\\u0026deg; (2θ) and the scanning speed 10 min\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e. The morphology and microstructure of the product were characterized by transmission electron microscope (JEM-100CXII, accelerating voltage 80 kV), high resolution transmission electron microscope (Philips Tecnai 20U-TWIN, accelerating voltage 200 kV) and scanning electron microscope (FE-SEM, S-4800, Hitachi, accelerating voltage 5 kV). X-ray photoelectron spectrometer (PHI-5300 ESCA spectrometer, Perkin Elmer, Al Kα as excitation light source) was used to analyze the surface properties of the samples. Before the spectrogram analysis, the electron binding energies of all elements were corrected with the C\\u003csub\\u003e\\u003cem\\u003e1s\\u003c/em\\u003e\\u003c/sub\\u003e peak at 284.6 eV as reference. Room temperature fluorescence spectrum (PL) and fluorescence lifetime of samples were measured by Agilent Cary Eclipse Fluorescence Spectrometer. The UV-VIS absorption spectrum of the sample at room temperature was tested by Agilent Cary Series UV-VIS spectrometer, and BaSO\\u003csub\\u003e4\\u003c/sub\\u003e was used as baseline correction before the test. The infrared spectrum of the sample was tested by NICOLET FT-IR spectrometer, and the KBr was used as the background.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Results and Discussion\",\"content\":\"\\u003cp\\u003e \\u003cb\\u003ePhase Structure and Morphology Characteristics\\u003c/b\\u003e ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e is a bimetallic oxide composed of ZnO and Ga\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e3\\u003c/sub\\u003e, with \\u003cem\\u003eFd-3m\\u003c/em\\u003e space group symmetry, a\\u0026thinsp;=\\u0026thinsp;b\\u0026thinsp;=\\u0026thinsp;c\\u0026thinsp;=\\u0026thinsp;8.335, and spinel structure with chemical formula AB\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, in which Zn\\u003csup\\u003e2+\\u003c/sup\\u003e occupying tetrahedral center, Ga\\u003csup\\u003e3+\\u003c/sup\\u003e occupying octahedral center,\\u003csup\\u003e\\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e21\\u003c/span\\u003e\\u003c/sup\\u003e as shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e\\u003cb\\u003e(a).\\u003c/b\\u003e Usually, the charge imbalance caused by the introduction of impurity ions is unfavorable to the luminous intensity of luminophores, so higher energy is needed to eliminate the charge imbalance, such as calcination at high temperature for a long time.\\u003csup\\u003e\\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e22\\u003c/span\\u003e\\u003c/sup\\u003e The effective compensation factor φ when ions are substituted was calculated according to the formula \\u003cem\\u003eφ\\u0026thinsp;=\\u0026thinsp;Z/r\\u003c/em\\u003e, in which \\u003cem\\u003eZ\\u003c/em\\u003e is the charge number of ions and \\u003cem\\u003er\\u003c/em\\u003e is the effective radius of ions.\\u003csup\\u003e\\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e23\\u003c/span\\u003e\\u003c/sup\\u003e The greater the difference of \\u003cem\\u003eφ\\u003c/em\\u003e, the more difficult it is to substitute ions. As shown in \\u003cb\\u003eTable \\u003cspan refid=\\\"MOESM1\\\" class=\\\"InternalRef\\\"\\u003eS1\\u003c/span\\u003e\\u003c/b\\u003e, for hexa-coordinate substitution of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, the effective compensation factor \\u003cem\\u003eφ\\u003c/em\\u003e is 2.41, which is much lower than that of Ga\\u003csup\\u003e3+\\u003c/sup\\u003e 4.83, so it is difficult for Mn\\u003csup\\u003e2+\\u003c/sup\\u003e to replace Ga\\u003csup\\u003e3+\\u003c/sup\\u003e, while easy to replace Zn\\u003csup\\u003e2+\\u003c/sup\\u003e due to the small difference of effective compensation factor.\\u003csup\\u003e\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e\\u003c/sup\\u003e Therefore, in the substitution reaction of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ions with similar effective radii are easy to be substituted with each other, that is, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e replaces Zn\\u003csup\\u003e2+\\u003c/sup\\u003e to produce four coordinate substitutions, and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e replaces Ga\\u003csup\\u003e3+\\u003c/sup\\u003e to produce six coordinate substitution.\\u003csup\\u003e\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e24\\u003c/span\\u003e\\u003c/sup\\u003e\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe SEM photos of the three nanomaterials (ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e) with different magnification is shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e\\u003cb\\u003e(b)-(g)\\u003c/b\\u003e. They all present a flower-like nanostructure of about 5\\u0026micro;m, which is composed of multiple nanosheet-level substructures with a thickness of 6\\u0026ndash;10 nm interspersed together. The difference between the three samples is that the nanosheets composed of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e are thicker and the degree of curling of the nanosheets is smaller, while the nanosheets doped with Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e are thinner, and the nanosheets are freely curled to form spherical nanoflowers. As shown in \\u003cb\\u003eFigure \\u003cspan refid=\\\"MOESM1\\\" class=\\\"InternalRef\\\"\\u003eS1\\u003c/span\\u003e\\u003c/b\\u003e. Zn, Ga, O and the corresponding doped elements Mn and Cr are uniformly distributed in the flower-like nanostructures confirmed by the element distribution surface scans. The flower-like structure of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e can also be seen from the TEM photos in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e\\u003cb\\u003e(h)-(j)\\u003c/b\\u003e. Each flower is composed of the sub-structure of nano-flakes, and the size of nano-flowers is about 5 \\u0026micro;m. From the contrast of the electron microscope photos, it can be clearly seen that the nano-flakes constituting the flower-like structure become thinner in turn, which is similar to that of Scanning electron microscope (SEM). The phenomenon may be due to the impurity ions adsorbed on the initial grain surface during hydrothermal process, which inhibiting the crystallization of the material to some extent, preventing the grain growth in some directions, and resulting in the formation of thinner nanosheets. High-resolution photos and corresponding selective electron diffraction photos of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e are shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e\\u003cb\\u003e(k)\\u003c/b\\u003e. The lattice spacing 0.44nm is corresponding to the (200) crystal plane of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, and the selective electron diffraction photo clearly shows single crystal structure of a ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e nanoflake. In the single crystal structure of the sheet, the diffraction points correspond to (200) and (111) crystal plane. The direction of the crystal zone axis is confirmed to [011] by calculating, therefore the exposed surface of the nanoplate is (110) plane.\\u003c/p\\u003e \\u003cp\\u003eAs shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e\\u003cb\\u003e(a)\\u003c/b\\u003e the diffraction peaks of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e all correspond to the diffraction peaks of standard card JCPDS38-1240 ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, which are cubic spinel structure. After doping Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, the intensity of the diffraction peak decreases, and the corresponding FWHM(full width at half maximum) increases in sequence. The results of X-ray diffractometer (XRD) analysis also indicate that the secondary structure nanosheets that make up the nanoflowers become thinner in turn after doping Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, which consistent precisely with the observation results of SEM and transmission electron microscopy (TEM). As shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e\\u003cb\\u003e(b)-(e)\\u003c/b\\u003e the electron binding energies of 2p\\u003csub\\u003e1/2\\u003c/sub\\u003e orbitals and 2p\\u003csub\\u003e3/2\\u003c/sub\\u003e orbitals of Ga are located at 1143.6 eV and 1116.8 eV, respectively. And the electron binding energies of 2p\\u003csub\\u003e1/2\\u003c/sub\\u003e orbitals and 2p\\u003csub\\u003e3/2\\u003c/sub\\u003e orbitals of Zn are located at 1043.8 eV and 1021.1 eV, respectively. The characteristic peaks of electron binding energies located at 654.4 eV and 645.5 eV belong to 2p\\u003csub\\u003e1/2\\u003c/sub\\u003e orbitals and 2p\\u003csub\\u003e3/2\\u003c/sub\\u003e orbitals of Mn, respectively and manganese ions show\\u0026thinsp;+\\u0026thinsp;2 valences. The characteristic peaks of electron binding energy at 586.5eV and 576.5eV respectively belong to 2p\\u003csub\\u003e1/2\\u003c/sub\\u003e orbitals and 2p\\u003csub\\u003e3/2\\u003c/sub\\u003e orbitals of Cr and chromium ions show\\u0026thinsp;+\\u0026thinsp;3 valences. The intensity of these characteristic peaks is small due to the low contents of Mn and Cr.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eInfrared and ultraviolet spectral characteristics\\u003c/b\\u003e In order to understand the chemical composition of the sample, the Fourier transform infrared spectrum is conducted. The Fourier Transform infrared spectroscopy (FT-IR) of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e: Cr\\u003csup\\u003e3+\\u003c/sup\\u003e in \\u003cb\\u003eFigure \\u003cspan refid=\\\"MOESM2\\\" class=\\\"InternalRef\\\"\\u003eS2\\u003c/span\\u003e\\u003c/b\\u003e also indicate the the samples were binary metal oxides consisting of Zn-O and Ga-O groups. As showed in \\u003cb\\u003eFigure \\u003cspan refid=\\\"MOESM2\\\" class=\\\"InternalRef\\\"\\u003eS2\\u003c/span\\u003e\\u003c/b\\u003e, the broad absorption peak at the 3445cm\\u003csup\\u003e-\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u003c/sup\\u003e wavelength belongs to the stretching vibration of O-H and N-H. The stretching vibration of N-H may come from the residual ethylenediamine in the sample, but there is no obvious stretching vibration peak of it near 1190cm\\u003csup\\u003e-\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u003c/sup\\u003e. Therefore, the residual ethylenediamine may be very small and can be ignored after repeated cleaning of water and anhydrous ethanol. In the fingerprint region at low wavelength, the larger peaks of 585cm\\u003csup\\u003e-\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u003c/sup\\u003e and 425cm\\u003csup\\u003e-\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u003c/sup\\u003e are attributed to the vibration absorption of Zn-O and Ga-O, respectively. Through the infrared spectrum analysis, no other vibration peaks are observed except Zn-O and Ga-O in the sample, so it is determined that the sample is a binary metal oxide composed of Zn-O group and Ga-O group. The UV-vis absorption spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e samples are shown in \\u003cb\\u003eFigure S3\\u003c/b\\u003e. It can be seen from the figure that the absorption regions of the three samples are basically the same, and there is only absorption in the region smaller than 350nm. It is also confirmed that ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e can only be excited at wavelengths less than 350nm. However, in the 300-350nm wavelength region, compared with the absorption peak of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, the absorption of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e increases slightly, which may be due to the absorption of a small amount of Mn and Cr itself, because the amount of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e is very small, only 0.4% and 1%, so the absorption of these two elements is also very weak.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eLuminescent properties\\u003c/b\\u003e The excitation and emission spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e are shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e\\u003cb\\u003e(a)-(c)\\u003c/b\\u003e. For undoped ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, three peaks can be seen in the excitation spectrum, which are located at 226 nm 239 nm and 257 nm, respectively. These excitation peaks are caused by the charge transfer from O\\u003csup\\u003e\\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e-\\u003c/sup\\u003e to octahedral center Ga\\u003csup\\u003e3+\\u003c/sup\\u003e and the ultraviolet absorption of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e itself.\\u003csup\\u003e\\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e25\\u003c/span\\u003e\\u003c/sup\\u003e The emission spectrum obtained using226nm as the excitation wavelength is a broad peak with the highest peak of 456nm in the range of 340-750nm. This broad emission peak is in all probability caused by the self-excitation of Ga- O hexahedron in the spinel structure. The luminescent properties of fluorescent host materials are usually changed by introducing impurity ions\\u003csup\\u003e\\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e26\\u003c/span\\u003e\\u003c/sup\\u003e, that is also applicable to ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e host materials. Mn\\u003csup\\u003e2+\\u003c/sup\\u003e-doped ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e has green fluorescence emission, as shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e\\u003cb\\u003e(b)\\u003c/b\\u003e, Except for the charge transfer from O\\u003csup\\u003e\\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e-\\u003c/sup\\u003e to Ga\\u003csup\\u003e3+\\u003c/sup\\u003e in the octahedral center and the ultraviolet absorption of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e itself, the absorption of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e excites a red shift of 32 near 300nm, which is consistent with the analysis of ultraviolet-visible absorption spectrum in \\u003cb\\u003eFigure S3\\u003c/b\\u003e. Due to the activation of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, the emission spectrum with the highest emission peak of 505 nm is located in the range of 470\\u0026ndash;600 nm with the excitation wavelength of 226 nm.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eAfter enlarged locally as shown in \\u003cb\\u003eFigure S4\\u003c/b\\u003e, the five smaller excitation peaks located between 351-443nm and centered at 351nm, 379nm, 410nm, 422nm and 443nm respectively correspond to \\u003csup\\u003e5\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e4\\u003c/sup\\u003eE, \\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e2\\u003c/sub\\u003e, \\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e4\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e, \\u003csup\\u003e4\\u003c/sup\\u003eE\\u003csub\\u003e1\\u003c/sub\\u003e and \\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csub\\u003e4\\u003c/sub\\u003eT of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e.\\u003csup\\u003e27\\u003c/sup\\u003e When excited at 226nm, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e has green emission at 505nm, which belongs to the \\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e d orbital electron forbidden transition of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e.\\u003csup\\u003e11,17\\u003c/sup\\u003e This is the process of energy transfer from ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e matrix to Mn\\u003csup\\u003e2+\\u003c/sup\\u003e.\\u003csup\\u003e27\\u003c/sup\\u003e The transition process of \\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e is accompanied by strong 3d shell lattice vibration coupling, and is affected by crystal field and symmetric sites. If Mn\\u003csup\\u003e2+\\u003c/sup\\u003e is in a weak crystal field, i.e. tetrahedron, the splitting of excitation energy will be weak, which will be accompanied by high energy emission, that is, green light and if Mn\\u003csup\\u003e2+\\u003c/sup\\u003e is in a strong crystal field, i.e., octahedron, it will emit yellow or red light,\\u003csup\\u003e\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e27\\u003c/span\\u003e\\u003c/sup\\u003e which is consistent with our previous analysis of crystal structure. In our investigation, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e replaces Zn\\u003csup\\u003e2+\\u003c/sup\\u003e with similar ionic radius in cubic ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e matrix to generate tetrahedral coordination and emit green light, which is completely consistent with the test results of fluorescence spectrum.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe excitation and emission spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e are shown in Figs.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e\\u003cb\\u003e(c)\\u003c/b\\u003e. There is a wide excitation peak between 200\\u0026ndash;350 nm, including four intensity excitation peaks (226 nm, 240 nm, 257 nm, 266 nm), which related to the charge transfer transition of O\\u003csup\\u003e2\\u0026minus;\\u003c/sup\\u003e to the octahedral center Ga\\u003csup\\u003e3+\\u003c/sup\\u003e and the absorption transition with the belt, and the excitation spectrum of 300\\u0026ndash;350 nm is caused by the absorption of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e. A red emission peak at 696 nm was obtained by excitation at 226 nm, which was attributed to the \\u003csup\\u003e2\\u003c/sup\\u003eE-\\u003csup\\u003e4\\u003c/sup\\u003eA\\u003csub\\u003e2\\u003c/sub\\u003e characteristic transformation of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e.\\u003csup\\u003e28\\u003c/sup\\u003e Meanwhile, a similar red emission peak at 696 nm was obtained by excitation at 416 nm and 572 nm. These two excitation peaks at 416 nm and 572 nm are caused by d-d electron-electron transitions of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, \\u003csup\\u003e\\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e24\\u003c/span\\u003e,\\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e29\\u003c/span\\u003e\\u003c/sup\\u003e corresponding to the \\u003csup\\u003e4\\u003c/sup\\u003eA\\u003csub\\u003e2\\u003c/sub\\u003e-\\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e1\\u003c/sub\\u003e and \\u003csup\\u003e4\\u003c/sup\\u003eA\\u003csub\\u003e2\\u003c/sub\\u003e-\\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e2\\u003c/sub\\u003e characteristic transitions of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, respectively.\\u003csup\\u003e\\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e30\\u003c/span\\u003e\\u003c/sup\\u003e\\u003c/p\\u003e \\u003cp\\u003eUndoped, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e doped and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e doped ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e have blue, green and red emission properties under ultraviolet (UV) excitation, respectively. The excitation wavelengths used in the emission spectra of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e are all 226nm, indicating that the hetero ions in ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e can effectively enter the lattice of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e under hydrothermal conditions to replace Zn\\u003csup\\u003e2+\\u003c/sup\\u003e and Ga\\u003csup\\u003e3+\\u003c/sup\\u003e to form tetrahedral and octahedral coordination, respectively. This is related to the addition of an appropriate amount of ethylenediamine during hydrothermal. Ethylenediamine aqueous solution is a strongly alkaline solution, which plays an effective role in promoting the crystallization of materials and the entry of hetero ions into the crystal lattice of the matrix under the condition of hydrothermal high temperature and high pressure. We also conduct experiment keeping other conditions remaining the same without ethylenediamine in the synthesis. The obtained ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e doped with Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e does not show green and red emission properties after UV excitation, indicating that it is difficult for hydrothermal hetero ions to enter into the lattice of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e matrix under the condition of non-strong alkaline solvent.\\u003c/p\\u003e \\u003cp\\u003eThe fluorescence attenuation curves of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e are fitted exponentially as shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e\\u003cb\\u003e(d)\\u003c/b\\u003e. The attenuation curves of the three samples are all fitted by double exponents, which are in accordance with the formula.\\u003c/p\\u003e \\u003cp\\u003e \\u003cem\\u003eI\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;\\u003cem\\u003eI\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e1\\u003c/em\\u003e\\u003c/sub\\u003e exp(-\\u003cem\\u003et\\u003c/em\\u003e/\\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e1\\u003c/em\\u003e\\u003c/sub\\u003e)\\u0026thinsp;+\\u0026thinsp;\\u003cem\\u003eI\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e2\\u003c/em\\u003e\\u003c/sub\\u003e exp(-\\u003cem\\u003et\\u003c/em\\u003e/\\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e2\\u003c/em\\u003e\\u003c/sub\\u003e) (1)\\u003c/p\\u003e \\u003cp\\u003eWhere \\u003cem\\u003eI\\u003c/em\\u003e is the fluorescence intensity when the time is \\u003cem\\u003et\\u003c/em\\u003e, \\u003cem\\u003eI\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e1\\u003c/em\\u003e\\u003c/sub\\u003e and \\u003cem\\u003eI\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e2\\u003c/em\\u003e\\u003c/sub\\u003e are fitting constants, and \\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e1\\u003c/em\\u003e\\u003c/sub\\u003e and \\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e2\\u003c/em\\u003e\\u003c/sub\\u003e are fluorescence lifetime. After fitting, each sample corresponds to two millisecond lifetimes, a shorter lifetime \\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e1\\u003c/em\\u003e\\u003c/sub\\u003e and a relatively longer life \\u003cem\\u003eτ\\u003c/em\\u003e\\u003csub\\u003e\\u003cem\\u003e2\\u003c/em\\u003e\\u003c/sub\\u003e. The specific fitting parameters are shown in \\u003cb\\u003eTable \\u003cspan refid=\\\"MOESM2\\\" class=\\\"InternalRef\\\"\\u003eS2\\u003c/span\\u003e\\u003c/b\\u003e. The longer lifetimes of each sample of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csub\\u003e2+\\u003c/sub\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e correspond to the self-excitation of Ga-O in the bulk phase of luminescent materials, the \\u003csup\\u003e4\\u003c/sup\\u003eT\\u003csub\\u003e1\\u003c/sub\\u003e-\\u003csup\\u003e6\\u003c/sup\\u003eA\\u003csub\\u003e1\\u003c/sub\\u003e transition of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and the \\u003csup\\u003e2\\u003c/sup\\u003eE-\\u003csup\\u003e4\\u003c/sup\\u003eA\\u003csub\\u003e2\\u003c/sub\\u003e transition of Cr\\u003csup\\u003e3+\\u003c/sup\\u003e, respectively. The short lifetime of the three samples is due to the fact that the surface effect of the materials has a great influence on the luminescence lifetime. These materials are all composed of ultra-thin 6\\u0026ndash;10 nm nanosheets with large surface area, and the increase of surface atoms leads to the appearance of more activated ions on the surface of the nanosheets. However, the impurities, unsaturated bonds, vacancies and other surface defects on the surface of the nanoparticles will quenched the activated ions and lead to radiation-free transition, thus shortening the life of the activated ions.\\u003csup\\u003e\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e\\u003c/sup\\u003e\\u003c/p\\u003e \\u003cp\\u003eExcited by 254nm's handheld UV lamp, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e appear bright blue, green and red, respectively. Their optical photos are shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e\\u003cb\\u003e(a)\\u003c/b\\u003e. The solid fluorescence yields of blue, green, and red colors are 32.3, 36.5, and 40.7%, respectively. Under the light excitation of 226nm wavelength, the fluorescence emission spectra of the three materials are shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e\\u003cb\\u003e(b)\\u003c/b\\u003e. The maximum fluorescence emission spectra of the three materials are located in 456nm, 505nm and 696nm, respectively, which basically correspond to the central regions of blue, green and red. Their emission spectra are imported into the CIE color coordinate software, respectively, and the color coordinate diagram shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e\\u003cb\\u003e(c)\\u003c/b\\u003e is obtained. The color coordinates are located at (0.19, 0.23), (0.10, 0.65) and (0.66, 0.34), respectively, which indicates that any color including white in the triangular area connected by the three points can be obtained by changing the ratio of the three luminescent materials.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\"},{\"header\":\"Conclusions\",\"content\":\"\\u003cp\\u003eZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e nanoflowers with single size composed of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e flake substructures with a thickness of 6-10nm were synthesized by a simple hydrothermal method under the action of ethylenediamine template. The luminescence color of ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e is controlled by doping Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e. Under UV excitation, undoped ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e doped with Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e have blue, green and red emission properties, respectively. The luminescence properties of the same matrix material with three primary colors are obtained. The blue, green and red fluorescence comes from the self-excited electron transfer of Ga-O itself and the 3d electron energy transfer of Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e. These ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e-based fluorescent nanomaterials are expected to be used in color display, biological imaging and white light devices.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgement\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThanks for the support of the Experimental Center of Shandong University of Traditional Chinese Medicine and the Natural Science Foundation of Shandong Province (Grant No.: ZR2020 MB108, ZR2021QH232).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor contributions statement\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eYan Liu: Conceptualization, methodology, formal analysis, investigation, writing\\u0026mdash;original draft, writing\\u0026mdash;review and editing, Xinhuan Wan: conceptualization, methodology, invisualization, writing review \\u0026amp; editing, Funding acquisition. Tingting Zheng: conceptualization, data curation, formal analysis, funding acquisition, methodology, supervision, writing-original draft, writing-review \\u0026amp; editing. Xiuyun Zhang: supervision, conceptualization, methodology, invisualization, writing-review \\u0026amp; editing. Chen Chen: supervision, conceptualization, methodology, invisualization, writing-review \\u0026amp; editing.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eData availability\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eAll data generated or analyzed during this study are included in this published article (and its Supplementary Information files).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare no competing interests.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAdditional information\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eSupplementary Information.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eNie, J., Li, Y., Han, G. \\u0026amp; Qiu, J. In vivo clearable inorganic nanophotonic materials: designs, materials and applications. 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Modern Physics Letters B 30, doi:\\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1142/s0217984916500196\\u003c/span\\u003e\\u003cspan address=\\\"10.1142/s0217984916500196\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e (2016).\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eZhang, Y. \\u003cem\\u003eet al.\\u003c/em\\u003e Full Color Emission in ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e: Simultaneous Control of the Spherical Morphology, Luminescent, and Electric Properties via Hydrothermal Approach. \\u003cem\\u003eAdvanced Functional Materials\\u003c/em\\u003e 24, 6581\\u0026ndash;6593, doi:\\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1002/adfm.201402092\\u003c/span\\u003e\\u003cspan address=\\\"10.1002/adfm.201402092\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e (2014). \\u003c/li\\u003e\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":true,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"scientific-reports\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"scirep\",\"sideBox\":\"Learn more about [Scientific Reports](http://www.nature.com/srep/)\",\"snPcode\":\"\",\"submissionUrl\":\"\",\"title\":\"Scientific Reports\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Scientific Reports\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Zinc Gallate, Full Color, Fluorescent Material, Luminescence Property\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-2785059/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-2785059/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eGallate material, a luminescent matrix with excellent performance is normally prepared by vapor deposition or solid phase sintering method at high temperature, however, it has not been solved to prepare gallate-based fluorescent materials with full-color luminescent properties at low temperature. In this paper, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e undoped or doped with Cr or Mn nanoflowers composed of nanosheet-level structure were prepared by hydrothermal method at low temperature. Under ultraviolet light irradiation, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and ZnGa\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e:Cr\\u003csup\\u003e3+\\u003c/sup\\u003e display three primary colors of blue, green and red luminescence through self-excitation, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e and Cr\\u003csup\\u003e3+\\u003c/sup\\u003e excitation respectively. The solid fluorescence yields of blue, green, and red colors are 32.3, 36.5, and 40.7%, respectively. It is highly expected to be applied to color display, biological imaging, white light devices.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Preparation of ZnGa2O4 Nanoflowers and Their Full-color Luminescence Properties\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2023-04-28 19:37:03\",\"doi\":\"10.21203/rs.3.rs-2785059/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Major revision\",\"date\":\"2023-06-01T04:17:12+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2023-05-25T03:47:55+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"21fd7175-623d-4540-a388-0cbaa95fd9e0\",\"date\":\"2023-05-18T23:37:39+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2023-05-18T20:49:37+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2023-05-18T20:37:21+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvited\",\"content\":\"\",\"date\":\"2023-04-26T13:08:02+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2023-04-26T13:00:58+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Scientific Reports\",\"date\":\"2023-04-06T09:45:40+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"scientific-reports\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"scirep\",\"sideBox\":\"Learn more about [Scientific Reports](http://www.nature.com/srep/)\",\"snPcode\":\"\",\"submissionUrl\":\"\",\"title\":\"Scientific Reports\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Scientific Reports\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"bea51e53-7a15-411b-b678-87a3a76a7f47\",\"owner\":[],\"postedDate\":\"April 28th, 2023\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"published-in-journal\",\"subjectAreas\":[{\"id\":21028022,\"name\":\"Physical sciences/Materials science/Materials for optics\"},{\"id\":21028023,\"name\":\"Physical sciences/Materials science/Nanoscale materials\"}],\"tags\":[],\"updatedAt\":\"2023-09-07T15:11:35+00:00\",\"versionOfRecord\":{\"articleIdentity\":\"rs-2785059\",\"link\":\"https://doi.org/10.1038/s41598-023-41658-5\",\"journal\":{\"identity\":\"scientific-reports\",\"isVorOnly\":false,\"title\":\"Scientific Reports\"},\"publishedOn\":\"2023-09-02 15:08:58\",\"publishedOnDateReadable\":\"September 2nd, 2023\"},\"versionCreatedAt\":\"2023-04-28 19:37:03\",\"video\":\"\",\"vorDoi\":\"10.1038/s41598-023-41658-5\",\"vorDoiUrl\":\"https://doi.org/10.1038/s41598-023-41658-5\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-2785059\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-2785059\",\"identity\":\"rs-2785059\",\"version\":[\"v1\"]},\"buildId\":\"ApUGefWb6u5IBVtyqm6d5\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}