Exploration of impact of ammonia concentration on the surface morphology, optical and wettability performance of SiO2 thin film

Exploration of impact of ammonia concentration on the surface morphology, optical and wettability performance of SiO2 thin film | 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 Exploration of impact of ammonia concentration on the surface morphology, optical and wettability performance of SiO 2 thin film Krishnapriya Pradhan, Tanmay Badapanda, Jasashree Ray, Surya Prakash Ghosh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4823922/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 An effective sol-gel technique that yields conformal coatings with amorphous silica (SiO 2 ) is the Stöber method. In the present manuscript, we have synthesis SiO 2 thin film using the solgel-based Stober method and deposited on glass substrates by spin coating technique. We have examined the impact of ammonia concentration during the synthesis process of silica thin films on the structural, morphological, optical, and wetting characteristics. XRD analysis confirmed the presence of amorphous silica phase for all thin film samples. Elemental analysis illustrated the presence of Si and O element in the sample without any impurity. Moreover, the average diameter of silica nanoparticles has been obtained by utilizing Field emission scanning electron microscopy (FESEM). The variation of optical bandgap of silica thin films prepared at different ammonia concentration was investigated via UV-Vis spectrum. The wetting properties of silica thin films have been studied from the contact angle measurement concerning to variation in ammonia concentration. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Silica (silicon dioxide) is an oxide complex i.e. combination of silicon and oxygen atoms joined consecutively. Within the silica molecules, every silicon atom connects with four oxygen atoms while every oxygen atom connects with two silicon atoms by Si-O bonds. The silicon and oxygen atoms have a bond angle of 109.5 o , and this bond has a length that varies from 1.54 to 1.69 Å. [ 1 ].The siloxane bonds, which are silicon-oxygen-silicon bonds have angle that can vary from 120 ο to 180 ο based on changes in bond energy. These unique properties of silica are attributed to the various shapes and compositions due to high bond energy (621.7 kJ/mol) of Si-O bonds [ 1 , 2 ]. These silica materials have high level of chemical inertness with excellent level of thermal resistance and a good mechanical properties as compared to other oxides like ZnO, TiO 2 [ 3 ]. The relevance and interest in silica thin films has grown recently, not only in the scientific but also in industrial fields [ 4 , 5 ], such as catalysis, chemical mechanical polishing [ 6 ],pigments [ 7 ] and stabilizers [ 8 ]. For synthesis of silica thin films, various methods were proposed, such as chemical vapor deposition (CVD), plasma manufacturing, microemulsion method, electron-beam evaporation, sol–gel synthesis, and magnetron sputtering [ 9 – 13 ]. All these techniques have many advantages such as fast deposition speed, require of low temperature, multiple layers of coating, and minimal damage to the film, but still these techniques have a few drawbacks. However, the film deposition rate of the CVD process is quite slow, and it often involves flammable, very toxic, or explosive reactants such as SiH 4 and SiH 2 Cl 2 . Guo et al. [ 14 ] fabricated an ultrathin SiO 2 layer by using SiCl 4 at room temperature in CVD method. Although magnetron sputtering is an advantageous method for thin film deposition, it has some major drawbacks such as strong magnetic materials cannot achieve high speed sputtering at low temperatures due to plasma instability and limitations in magnetic flux [ 15 ], which make this method complex. In addition, oxygen deficiency is another inadequacy of silica films prepared by magnetron sputtering [ 16 ]. Overall, the vacuum-based techniques are not budget friendly and requires high-cost equipment such as expensive crucible, electron-gun and its power supply are required in e-beam evaporation method. Sol-gel method is regarded as the most significant and frequently used technique due to various advantages including its ability to synthesise at low temperatures with ideal PH to yield high purity and its versatility in adjusting reaction mixture compositions to control the rate of reaction. Again, the sol-gel synthesis process can be classified as precipitated synthesis, Stöber method, and biomimetic sol-gel synthesis process [ 17 , 18 ]. It has been illustrated that the Stöber process is the most convenient and efficient method for fabricating spherical silica nanoparticles because the reaction state is easy to control and carried out, and the reactants are normal [ 19 ]. This approach involves hydrolysis and condensation of tetraethyl orthosilicate (TEOS) as silicon alkoxide which hydrolysed with ethanol and water in presence of ammonia as basic catalyst that described by the following three equations: Hydrolysis: ≡ Si–OR + H 2 O ↔≡ Si–OH + ROH (1) Alcohol condensation: ≡ Si–OR + ≡ Si–OH ↔≡ Si–O–Si ≡ + ROH (2) Water condensation: ≡ Si–OH + ≡ Si–OH ↔≡ Si–O–Si ≡ + H 2 O (3) It is widely reported that the diameter of silica nanoparticles can be controlled by the concentration of TEOS, water, and ammonia [ 20 – 22 ]. Wang et al. [ 23 ] verified that by altering TEOS concentration, the size of silica nanoparticles increased while the molar concentrations of water and ammonia remained constant. Whenever the concentration of TEOS enhanced, more primary particles caused to raise the hydrolytic rate. Due to production of additional short chains of TEOS, the primary particles are spontaneously aggregated to form stable secondary particles that significantly increase particle size distribution in polydisperse pattern [ 24 , 19 ]. Additionally, when water concentration increased, the hydrolysis rate as well as the interaction of silica molecules during the condensation process both decreased, resulting in smaller particles with an uneven distribution [ 24 ]. Ammonia is the most significant experimental parameter that influences the morphology of silica particles more than the concentrations of TEOS and water [ 25 ]. There are several methods reported for deposition process such as dip coating, spray pyrolysis, spin coating and drop casting method. But the spin coating approach has been reported as the most practical and useful way to deposit various materials as solutions, especially polymers, biomaterials, and nanoparticles [ 26 , 27 ]. Thus, it can be concluded that Stober process with spin coating method is one of the suitable method for the fabrication of silica thin films due to minimal cost. In this work, silica solution was synthesized by Stober method with variation in one of the growth parameters i.e. ammonia (catalyst) and coating process was followed by spin coating technique using glass substrates. The purpose of this work is to understand how the concentration of ammonia affects various characteristics of silica thin films like structure, particle size and its distribution, bandgap, and wetting behaviours. The present work included a brief discussion of the impact of ammonia concentrations on the optical, structural, morphological, and wetting characteristics of silica thin films. Experimental Section Materials: The following chemicals were purchased from merck and used without further purification: ethanol (96% purity), ammonium hydroxide (NH 4 OH, 28%), tetraethyl orthosilicate (TEOS, 99%), iso-propyl alcohol and acetone. Distilled water was used throughout the entire process. Microscopic glass slides were used as the substrates. Methodology: In the synthesis process, TEOS, ammonia, ethanol and distilled water were used as precursor, catalyst, and solvents. As, ammonia concentration was varied with higher molar concentration, the molar ratio of TEOS: NH 3 : H 2 O for sample 1(S1), sample 2(S2), sample3(S3) was taken as 0.5:8:3, 0.5:10:3, and 0.5:12:3 respectively. Initially, a solution of ammonia, ethanol, and distilled water was prepared in a 50 ml beaker under vigorous stirring (500 rpm) at 60 ο C temperature. When the temperature of the mixture reached 60 ο C, the TEOS (0.5 M) was added drop by drop into the solution. This solution was stirred under an air ambient atmosphere for 2 hrs. Subsequently this solution changed from clear solution to milky white colour. Then the solution was aged for 24 hrs. The glass substrates were ultrasonically cleaned using acetone, de-ionized water, and iso-propyl alcohol prior to the coating procedure. The silica solution was deposited on glass substrates by spin coating method which was operated for 60 sec at a speed of 2500 rpm having acceleration time 30 sec. After the deposition, post annealing has been carried out for 10 mins at 65 ο C on the hotplate. This process was repeated to deposit 8 layers of coating. After that, the prepared samples were annealed at 400 ο C for 1 hr in furnace. Characterization: The structural analysis was determined by utilizing a Rigaku powder X-ray difraction (XRD) apparatus associated with a Cu-Kα (λ = 0.15406 nm) radiation source and measurements were carried out within range 10° and 80°. The morphology of the silica thin films was investigated using a high-resolution field-emission scanning electron microscope (FESEM; JEOL, JSM7610F Plus) equipped with an energy dispersive X-ray analysis (EDX) apparatus from the Octane Elect EDS facility. An UV-Vis-NIR spectrophotometer (Perkin Elmer, Lambda 1050) was used to measure the absorption spectra of thin films in the 200–800 nm range. The water contact angle was measured by Ossila contact angle goniometer to determine the wettability nature of silica thin films. Result and Discussions 3.1. XRD Analysis: XRD patterns of Stober synthesized silica thin films deposited on glass substrates with variation in ammonia concentration was observed from Fig. 2. No sharp peak other than a broad hump-shaped diffraction peak centred at 2θ = 24.1° have been observed for all the samples, which signifies the amorphous silica without any ordered structure. The above result is in accordance with JCPDS No. 0085 − 29 [28]. Further, evidence of amorphous silica phase signifies the hexagonal symmetry of quartz silica [JCPDS value (47–1144)]. XRD peaks which demonstrate that a small concentration variation in ammonia does not completely alter the structure of the silica sample. Also, there is no phase change when the concentration is changed, indicating the high purity of the silica thin films. 3.2. FESEM Analysis: Figure 3 depicts the FESEM micrograph of silica thin films coated on glass substrate for various ammonia concentrations. In addition, the impact of various ammonia concentrations on the particle size and its distribution of samples have been also analysed from the FESEM images. A uniformly distributed spherical shaped silica nanoparticles has been observed throughout the glass substrates with large surface coverage. To measure the size of the nanoparticles imagej software was used. It has been observed that by varying ammonia concentration as 8M, 10M and 12 M, the corresponding size of nanoparticles was found to be around 200 ± 18 nm, 256 ± 17 nm, 332 ± 25 nm respectively. Further, it can be inferred that the nanoparticles are not closely packed, rather in some regions one can find some packing defects. These random distribution and absence of closed packing can be attributed to the coating process of spin coating method. Although the material will spread due to the forces acting on the liquid during the spinning process, the unwetted area of the substrate will cause the coating solution to resist, leaving a void, while the sample is stationary [29]. Effect of Ammonia Concentration on the Morphology of Silica thin films: The formation of spherical shaped silica nanoparticles and the increment in size with ammonia could be explained based on rates of hydrolysis and condensation followed by equations (1) and (2). Basically, in the hydrolysis reaction, the hydroxyl group of TEOS attacked the silica molecule, forming silicic acid in the presence of ammonia as a catalyst, and the reaction was identified as a nucleophilic reaction. The condensation reaction takes place in an alkaline condition when silicic acid attacks another silica molecule by releasing its hydrogen atom. The reaction rate of hydrolysis was faster than the rate of condensation because of fewer intermediates in this process. The hydrolytic rate increased in accordance with a rise in ammonia concentration, which increased the size of the SiO 2 particle. Here, equations (4) and (5) demonstrated how TEOS hydrolyzed and condensed in the presence of NH 3 , as catalyst. where R is an alkyl group C 2 H 5 . In this reaction, ionic species are SiO − , OH − , NH 4 + and H + . H + concentration is much smaller than OH − concentration in basic solution. Thus, SiO − , OH − and NH 4 + are predominately present in solution. This results in hydrolysed products to condensed with each other to form spherical shaped nanoparticles. Thus, hydroxyl concentration in the solution has a significant task to control hydrolysed product and form spherical silica particles. Besides, ammonia was used as catalyst to adjust the hydroxyl concentration throughout the reaction system. Moreover, ammonia is alkalescent and partially disintegrates to control hydroxyl concentration in the solution[30]. Therefore, a higher amount of hydroxyl was produced when ammonia concentration increased, and a greater number of hydroxyl groups were substituted with TEOS alkoxy groups. Thus, it can be concluded that higher ammonia concentration is suitable to obtain larger size spherical shaped silica nanoparticles. 3.3. EDX Analysis: Figure 4 (a-b) shows the elemental mapping images and EDX spectrum of the Stober synthesized silica thin films. The EDS spectrum displays a strong signal related to occurrence of oxygen and silicon. Further, from the quantitative results obtained from the EDX measurement the atomic wt% of silicon and oxygen was found to be 79.9% and 20.1% respectively. The elemental mapping images depicted in Fig. 4(a) confirm the existence of Si and O in the sample. Thus, the purity of the silica nanoparticle samples is greater than 99.9% as traces of no other impurity elements have been observed in the EDX spectrum. Absence of impurity in this data signifies that the EDX result of the synthesized silica nanoparticles are consistent with the XRD results obtained. 3.4. UV- visible Analysis: Figure 5 illustrates the UV-visible absorbance spectra of silica thin films at different ammonia concentrations in the 200–700 nm range. As shown in Fig. 5 (a), the absorbance peak exhibited a clear shift in the UV–Vis range i.e. 290 nm -300 nm with changes of their particle size. The wavelength corresponding to the absorbance peaks blue shifted with the increase of silica nanoparticle sizes i.e. because of larger numbers of neighbouring atoms and silanol groups. Moreover, the rearrangement of components in silica thin films as well as an increase in disorder, number of vacancies, and particle size could be responsible for this blue shift. Such various significant features of silica thin films cause a considerable increase of the optical band gap energy [31]. Thus, the following Tauc equation was used to determine the band gap of the silica thin film sample using the UV–visible absorption spectra [32]. $$\:\left(\alpha\:h\nu\:\right)=A{(h\nu\:-Eg)}^{n}$$ 6 This equation represents α, hν, A, Eg, and n as the absorption coefficient, the incident photon energy, proportionality constant, optical band gap, and dimensionless parameter, respectively. For an indirect band gap energy, n = 2, but for a direct band gap energy, n = 1/2. By using Eq. (6), a graph between \(\:{\left(\alpha\:h\nu\:\right)}^{2}\)and hν was plotted as shown in Fig. 5 (b) and the optical energy band gap of samples S1, S2, and S3 are observed at 3.50 eV, 3.57 eV, and 3.67 eV respectively. Generally, a higher density of metallic cations is typically found in pristine samples, which contributes to the abundance of independent electrons in the crystal lattice. These electrons gain energy and increase their kinetic energy when a light beam strikes the sample. The current flow of the material increases and the band gap energy decreases as a result of these electrons jumping to the conduction band. However, the material density is decreased in amorphous silica, which lowers the amount of free electrons in the lattice and raises the energy gap between the valence and conduction bands with increasing the energy bandgap [33]. Another notable characteristic has been observed in silica thin film samples i.e. the absorbance spectra become extremely low at 450 nm, indicating that any radiation above 450 nm is not absorbed by the silica thin films. This suggests that the films block UV radiation and only permit light in the visible spectrum to get through. Thus, this is the one of advantage of silica thin films that block the ultraviolet part [34]. 3.5. Wettability Analysis: The static water contact angle of silica thin films was determined by gently dropping 1µL of distilled water onto the coated surface using a micro-syringe. For each measurement the droplets were replicated at four different places on the coated substrate. The water contact angle (WCA) was measured by employing goniometer, which captured a picture of the droplet instantly as it was placed on the surface. Figure 6 (a-d) shows the wetting behaviour of uncoated and silica coated glass substrates annealed at 400°C temperature for 1 hr. The method for contact angle analysis was first calibrated by comparing the water contact angles of glass, which is found to be around 48°. The water droplet depicts higher contact angle on an uncoated glass, whereas after the deposition of silica nanoparticles, water contact angle (WCA) shows low contact angle. Further it is well understood that the thermal treatment of silica coated glass substrates results in change in surface roughness which leads to super-hydrophilic surface. Thus, it has been found that on the flat glass surface, the water contact angle was observed as 48°, however the silica coated glass displays super-hydrophilicity with WCA around 4.5°. This can be explained based on the presence of high energy OH bonds i.e. the hydrophilicity of silica thin films is due to the density of surface hydroxyl groups. Good hydrophilicity is produced when the surface hydroxyl groups generate hydrogen bonds with water molecules, which is responsible for altering the wetting state from Cassie-Baxter state (superhydrophobic) to Wenzel state (superhydrophilic) [35]. Hydroxylation occurs when acetone solvent is used for surface treatment. A significant improvement in the variation of contact angles can be observed from a statistical analysis of all the samples. In Fig. 6 (e), it has been observed that with increasing in particle size, contact angle also increased from 4.5 ο to 15.3 ο . This is due to correlation in particle size, surface energy and contact angle. The variation in nanoparticle size and contact angle could be caused by the surface energy. The surface to volume ratio increases with decreasing nanoparticle size, increasing surface free energy and causing the contact angle to decrease. In the case of larger particles, the opposite occurs [36]. Hence it can be concluded that, the wetting behaviour of any surface depends on both surface chemistry and surface topography. Conclusion In this current work, silica thin films were synthesized by Stober process with variation in ammonia concentration followed by spin coating on glass substrates. The XRD result confirmed the broad amorphous diffraction peak centred at 2θ = 24.1 ο . Morphological analysis depicts spherical shaped silica nanoparticles which increased from 200 nm – 350 nm with increasing in ammonia concentration. From elemental mapping and EDX spectrum the atomic wt% of Si and O was found to be 79.9% and 20.1%, respectively, which confirms the presence of Si and O without impurities. The band gap of silica thin films was increased from 3.50 eV to 3.67 eV with increase in ammonia concentration. It was confirmed by the wettability studies that the wetting characteristics are dependent on surface morphology, as the contact angle increased from 4.5 ο to 15.3 ο . Declarations Author Contribution All authors have contributed to the methodology and experiment. K. Pradhan: Investigation, Methodology, Formal analysis, Software, Validation, Writing– original draft, S.P. Ghosh: Formal analysis, Writing– review & editing; T. Badapanda, J. Ray: Resources, Visualization, Supervision, Writing- review & editing. All authors read and approved the final manuscript. Acknowledgement The authors express their sincere thanks to Dr. S.Anwar, Sr.Principal Scientist, Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar Odisha, for contact angle measurement. measurements. The authors are thankful to C V Raman Global University, Odisha for providing financial support to carry out the work. Data Availability: The data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon reasonable request. References A. Luthfiah, Y. Deawati, M. L. Firdaus, I. Rahayu, D. R. Eddy, Science and Technology Indonesia 6, 3(2021) P. U. Nzereogu, A. D. Omah, F. I. Ezema, E. I. Iwuoha, A. C. Nwanya, Hybrid Advances 4, (2023) S. Hernández, D. Hidalgo, A. Sacco, A. Chiodoni, A. Lamberti, V. Cauda, E. Tresso, G. Saracco, Physical Chemistry Chemical Physics 17, (2015) Y. Kobayashi, J. Imai, D. Nagao, M. 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Kumar, J. P. Singh, Journal of Applied Physics 103, 8(2008) . 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-4823922","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":340078857,"identity":"a988924a-67da-4f05-a19f-1eeef78c6769","order_by":0,"name":"Krishnapriya Pradhan","email":"","orcid":"","institution":"C.V. Raman Global University","correspondingAuthor":false,"prefix":"","firstName":"Krishnapriya","middleName":"","lastName":"Pradhan","suffix":""},{"id":340078858,"identity":"f2294413-865b-4aad-937b-3969e1a4fa04","order_by":1,"name":"Tanmay Badapanda","email":"","orcid":"","institution":"C.V. Raman Global University","correspondingAuthor":false,"prefix":"","firstName":"Tanmay","middleName":"","lastName":"Badapanda","suffix":""},{"id":340078859,"identity":"78b096d1-ef8f-4c67-9772-57b152dadd6d","order_by":2,"name":"Jasashree Ray","email":"","orcid":"","institution":"Kalinga Institute of Industrial Technology","correspondingAuthor":false,"prefix":"","firstName":"Jasashree","middleName":"","lastName":"Ray","suffix":""},{"id":340078860,"identity":"62dfb58d-3653-49a4-8aca-b383a8cdd12c","order_by":3,"name":"Surya Prakash Ghosh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABLklEQVRIie2PP0vDQBTAL0Suy0nXF9TkK0QCUSjiV0koXJfL5CqSKV1q55NA/QqdSsfCYV0iricUEQpXEIVCQVSqmITilAzdBO833PvD+/HeIaTR/GUAIZyHSZ6Zk6Le30bBQVGTbRTiFo1axeGRgo/xo2N1b9UT+pzZTtpbPcvzY4Ia4mZYobiy41uX2dlhStiRa/SV587uRi02zQ8jlMoqBSiG3SQwBohhMHoiHEI08vKc5Bf6VYrDKba+kuB00FyoUrnmTHnsu15BkuK9fEuYQuADehdhLJk5j5J6xc2U2TrIgvYVf/EhjIXnSuqbUR8IrvmL06XGw+s4OOH3HQXLtbAd3p6v2NuF3WyIaeVhCO2AEW/SMCkDhvKtHi8wl78KWm869dMajUbzD/kBFwplvhi+GTgAAAAASUVORK5CYII=","orcid":"","institution":"C.V. Raman Global University","correspondingAuthor":true,"prefix":"","firstName":"Surya","middleName":"Prakash","lastName":"Ghosh","suffix":""}],"badges":[],"createdAt":"2024-07-29 18:18:44","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4823922/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4823922/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":63301338,"identity":"2b7cba3b-5a0f-4e1d-b88b-0531ac19b7f1","added_by":"auto","created_at":"2024-08-26 16:18:56","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":165403,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of synthesis process of silica solution by Stober method\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/d5bca7e666a271631e03c714.png"},{"id":63301336,"identity":"fd8f9efa-9686-4782-a23f-194e48a97b68","added_by":"auto","created_at":"2024-08-26 16:18:55","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":171415,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffraction pattern of silica thin film samples (a)S1, (b)S2, (c)S3\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/f5e7d587f63d60d334440ed6.png"},{"id":63301307,"identity":"4ac038e9-1ec9-43e5-b40a-0d0435754924","added_by":"auto","created_at":"2024-08-26 16:18:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":960960,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM micrograph and particle size distribution histograms of silica nanoparticles with variation in ammonia concentration (a),(d) 8M; sample1, (b),(e)10 M;sample2, (c),(f)12M; sample3 on glass substrate\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/bb7033ed50ff348418892b77.png"},{"id":63301308,"identity":"e82d8a9f-e17e-496e-a9cd-95e55931e957","added_by":"auto","created_at":"2024-08-26 16:18:49","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":693959,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Elemental mapping images, (b) EDX spectrum of Stober synthesized silica nanoparticles coated on glass substrate of sample 3\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/72cf1152f9e0d07c35abe14e.png"},{"id":63301335,"identity":"00d51379-0a4b-4e9e-8a58-d533d08fd753","added_by":"auto","created_at":"2024-08-26 16:18:55","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":186777,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Absorbance spectra and (b)optical band gap of silica nanoparticle thin films varying ammonia concentration\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/e7242eb1090e0f0606127e93.png"},{"id":63301394,"identity":"a7baea72-84da-4e9b-95bb-d6d3a6c0c5b9","added_by":"auto","created_at":"2024-08-26 16:18:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":247821,"visible":true,"origin":"","legend":"\u003cp\u003econtact angles of (a) bare glass(uncoated), (b)sample1 (c) sample 2 (d) sample 3 (e) diagram of water contact angle with different particle size of silica samples.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/c116b62a451eb3beb4d85540.png"},{"id":65761965,"identity":"3517c5b4-8f8c-4ed2-8d34-6ed5590bc1ab","added_by":"auto","created_at":"2024-10-02 10:02:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2998928,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4823922/v1/df5799ee-5036-4a86-a5ff-cd3829a6c2c1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eExploration of impact of ammonia concentration on the surface morphology, optical and wettability performance of SiO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e thin film\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSilica (silicon dioxide) is an oxide complex i.e. combination of silicon and oxygen atoms joined consecutively. Within the silica molecules, every silicon atom connects with four oxygen atoms while every oxygen atom connects with two silicon atoms by Si-O bonds. The silicon and oxygen atoms have a bond angle of 109.5\u003csup\u003eo\u003c/sup\u003e, and this bond has a length that varies from 1.54 to 1.69 Å. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].The siloxane bonds, which are silicon-oxygen-silicon bonds have angle that can vary from 120\u003csup\u003eο\u003c/sup\u003e to 180 \u003csup\u003eο\u003c/sup\u003e based on changes in bond energy. These unique properties of silica are attributed to the various shapes and compositions due to high bond energy (621.7 kJ/mol) of Si-O bonds [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These silica materials have high level of chemical inertness with excellent level of thermal resistance and a good mechanical properties as compared to other oxides like ZnO, TiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The relevance and interest in silica thin films has grown recently, not only in the scientific but also in industrial fields [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], such as catalysis, chemical mechanical polishing [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e],pigments [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and stabilizers [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor synthesis of silica thin films, various methods were proposed, such as chemical vapor deposition (CVD), plasma manufacturing, microemulsion method, electron-beam evaporation, sol–gel synthesis, and magnetron sputtering [\u003cspan additionalcitationids=\"CR10 CR11 CR12\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e–\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. All these techniques have many advantages such as fast deposition speed, require of low temperature, multiple layers of coating, and minimal damage to the film, but still these techniques have a few drawbacks. However, the film deposition rate of the CVD process is quite slow, and it often involves flammable, very toxic, or explosive reactants such as SiH\u003csub\u003e4\u003c/sub\u003e and SiH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e. Guo et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] fabricated an ultrathin SiO\u003csub\u003e2\u003c/sub\u003e layer by using SiCl\u003csub\u003e4\u003c/sub\u003e at room temperature in CVD method. Although magnetron sputtering is an advantageous method for thin film deposition, it has some major drawbacks such as strong magnetic materials cannot achieve high speed sputtering at low temperatures due to plasma instability and limitations in magnetic flux [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], which make this method complex. In addition, oxygen deficiency is another inadequacy of silica films prepared by magnetron sputtering [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Overall, the vacuum-based techniques are not budget friendly and requires high-cost equipment such as expensive crucible, electron-gun and its power supply are required in e-beam evaporation method. Sol-gel method is regarded as the most significant and frequently used technique due to various advantages including its ability to synthesise at low temperatures with ideal PH to yield high purity and its versatility in adjusting reaction mixture compositions to control the rate of reaction. Again, the sol-gel synthesis process can be classified as precipitated synthesis, Stöber method, and biomimetic sol-gel synthesis process [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It has been illustrated that the Stöber process is the most convenient and efficient method for fabricating spherical silica nanoparticles because the reaction state is easy to control and carried out, and the reactants are normal [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This approach involves hydrolysis and condensation of tetraethyl orthosilicate (TEOS) as silicon alkoxide which hydrolysed with ethanol and water in presence of ammonia as basic catalyst that described by the following three equations:\u003c/p\u003e \u003cp\u003eHydrolysis:\u003c/p\u003e \u003cp\u003e≡ Si–OR + H\u003csub\u003e2\u003c/sub\u003eO ↔≡ Si–OH + ROH (1)\u003c/p\u003e \u003cp\u003eAlcohol condensation:\u003c/p\u003e \u003cp\u003e≡ Si–OR + ≡ Si–OH ↔≡ Si–O–Si ≡ + ROH (2)\u003c/p\u003e \u003cp\u003eWater condensation:\u003c/p\u003e \u003cp\u003e≡ Si–OH + ≡ Si–OH ↔≡ Si–O–Si ≡ + H\u003csub\u003e2\u003c/sub\u003eO (3)\u003c/p\u003e \u003cp\u003eIt is widely reported that the diameter of silica nanoparticles can be controlled by the concentration of TEOS, water, and ammonia [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e–\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Wang et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] verified that by altering TEOS concentration, the size of silica nanoparticles increased while the molar concentrations of water and ammonia remained constant. Whenever the concentration of TEOS enhanced, more primary particles caused to raise the hydrolytic rate. Due to production of additional short chains of TEOS, the primary particles are spontaneously aggregated to form stable secondary particles that significantly increase particle size distribution in polydisperse pattern [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Additionally, when water concentration increased, the hydrolysis rate as well as the interaction of silica molecules during the condensation process both decreased, resulting in smaller particles with an uneven distribution [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Ammonia is the most significant experimental parameter that influences the morphology of silica particles more than the concentrations of TEOS and water [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. There are several methods reported for deposition process such as dip coating, spray pyrolysis, spin coating and drop casting method. But the spin coating approach has been reported as the most practical and useful way to deposit various materials as solutions, especially polymers, biomaterials, and nanoparticles [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Thus, it can be concluded that Stober process with spin coating method is one of the suitable method for the fabrication of silica thin films due to minimal cost.\u003c/p\u003e \u003cp\u003eIn this work, silica solution was synthesized by Stober method with variation in one of the growth parameters i.e. ammonia (catalyst) and coating process was followed by spin coating technique using glass substrates. The purpose of this work is to understand how the concentration of ammonia affects various characteristics of silica thin films like structure, particle size and its distribution, bandgap, and wetting behaviours. The present work included a brief discussion of the impact of ammonia concentrations on the optical, structural, morphological, and wetting characteristics of silica thin films.\u003c/p\u003e "},{"header":"Experimental Section","content":"\u003cp\u003eMaterials:\u003c/p\u003e\n\u003cp\u003eThe following chemicals were purchased from merck and used without further purification: ethanol (96% purity), ammonium hydroxide (NH\u003csub\u003e4\u003c/sub\u003eOH, 28%), tetraethyl orthosilicate (TEOS, 99%), iso-propyl alcohol and acetone. Distilled water was used throughout the entire process. Microscopic glass slides were used as the substrates.\u003c/p\u003e\n\u003cp\u003eMethodology:\u003c/p\u003e\n\u003cp\u003eIn the synthesis process, TEOS, ammonia, ethanol and distilled water were used as precursor, catalyst, and solvents. As, ammonia concentration was varied with higher molar concentration, the molar ratio of TEOS: NH\u003csub\u003e3\u003c/sub\u003e: H\u003csub\u003e2\u003c/sub\u003eO for sample 1(S1), sample 2(S2), sample3(S3) was taken as 0.5:8:3, 0.5:10:3, and 0.5:12:3 respectively. Initially, a solution of ammonia, ethanol, and distilled water was prepared in a 50 ml beaker under vigorous stirring (500 rpm) at 60\u003csup\u003e\u0026omicron;\u003c/sup\u003eC temperature. When the temperature of the mixture reached 60\u003csup\u003e\u0026omicron;\u003c/sup\u003eC, the TEOS (0.5 M) was added drop by drop into the solution. This solution was stirred under an air ambient atmosphere for 2 hrs. Subsequently this solution changed from clear solution to milky white colour. Then the solution was aged for 24 hrs. The glass substrates were ultrasonically cleaned using acetone, de-ionized water, and iso-propyl alcohol prior to the coating procedure. The silica solution was deposited on glass substrates by spin coating method which was operated for 60 sec at a speed of 2500 rpm having acceleration time 30 sec. After the deposition, post annealing has been carried out for 10 mins at 65\u003csup\u003e\u0026omicron;\u003c/sup\u003eC on the hotplate. This process was repeated to deposit 8 layers of coating. After that, the prepared samples were annealed at 400\u003csup\u003e\u0026omicron;\u003c/sup\u003eC for 1 hr in furnace.\u003c/p\u003e\n\u003cp\u003eCharacterization:\u003c/p\u003e\n\u003cp\u003eThe structural analysis was determined by utilizing a Rigaku powder X-ray difraction (XRD) apparatus associated with a Cu-K\u0026alpha; (\u0026lambda;\u0026thinsp;=\u0026thinsp;0.15406 nm) radiation source and measurements were carried out within range 10\u0026deg; and 80\u0026deg;. The morphology of the silica thin films was investigated using a high-resolution field-emission scanning electron microscope (FESEM; JEOL, JSM7610F Plus) equipped with an energy dispersive X-ray analysis (EDX) apparatus from the Octane Elect EDS facility. An UV-Vis-NIR spectrophotometer (Perkin Elmer, Lambda 1050) was used to measure the absorption spectra of thin films in the 200\u0026ndash;800 nm range. The water contact angle was measured by Ossila contact angle goniometer to determine the wettability nature of silica thin films.\u003c/p\u003e"},{"header":"Result and Discussions","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e3.1. XRD Analysis:\u003c/h2\u003e\n \u003cp\u003eXRD patterns of Stober synthesized silica thin films deposited on glass substrates with variation in ammonia concentration was observed from Fig.\u0026nbsp;2. No sharp peak other than a broad hump-shaped diffraction peak centred at 2\u0026theta;\u0026thinsp;=\u0026thinsp;24.1\u0026deg; have been observed for all the samples, which signifies the amorphous silica without any ordered structure. The above result is in accordance with JCPDS No. 0085\u0026thinsp;\u0026minus;\u0026thinsp;29 [28]. Further, evidence of amorphous silica phase signifies the hexagonal symmetry of quartz silica [JCPDS value (47\u0026ndash;1144)]. XRD peaks which demonstrate that a small concentration variation in ammonia does not completely alter the structure of the silica sample. Also, there is no phase change when the concentration is changed, indicating the high purity of the silica thin films.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e3.2. FESEM Analysis:\u003c/h2\u003e\n \u003cp\u003eFigure 3 depicts the FESEM micrograph of silica thin films coated on glass substrate for various ammonia concentrations. In addition, the impact of various ammonia concentrations on the particle size and its distribution of samples have been also analysed from the FESEM images. A uniformly distributed spherical shaped silica nanoparticles has been observed throughout the glass substrates with large surface coverage. To measure the size of the nanoparticles imagej software was used. It has been observed that by varying ammonia concentration as 8M, 10M and 12 M, the corresponding size of nanoparticles was found to be around 200\u0026thinsp;\u0026plusmn;\u0026thinsp;18 nm, 256\u0026thinsp;\u0026plusmn;\u0026thinsp;17 nm, 332\u0026thinsp;\u0026plusmn;\u0026thinsp;25 nm respectively. Further, it can be inferred that the nanoparticles are not closely packed, rather in some regions one can find some packing defects. These random distribution and absence of closed packing can be attributed to the coating process of spin coating method. Although the material will spread due to the forces acting on the liquid during the spinning process, the unwetted area of the substrate will cause the coating solution to resist, leaving a void, while the sample is stationary [29].\u003c/p\u003e\n \u003cp\u003eEffect of Ammonia Concentration on the Morphology of Silica thin films:\u003c/p\u003e\n \u003cp\u003eThe formation of spherical shaped silica nanoparticles and the increment in size with ammonia could be explained based on rates of hydrolysis and condensation followed by equations (1) and (2). Basically, in the hydrolysis reaction, the hydroxyl group of TEOS attacked the silica molecule, forming silicic acid in the presence of ammonia as a catalyst, and the reaction was identified as a nucleophilic reaction. The condensation reaction takes place in an alkaline condition when silicic acid attacks another silica molecule by releasing its hydrogen atom. The reaction rate of hydrolysis was faster than the rate of condensation because of fewer intermediates in this process. The hydrolytic rate increased in accordance with a rise in ammonia concentration, which increased the size of the SiO\u003csub\u003e2\u003c/sub\u003e particle. Here, equations (4) and (5) demonstrated how TEOS hydrolyzed and condensed in the presence of NH\u003csub\u003e3\u003c/sub\u003e, as catalyst.\u003c/p\u003e\n \u003cp\u003e\u003cimg 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\" style=\"width: 629px; height: 172.034px;\" width=\"629\" height=\"172.034\"\u003e\u003c/p\u003e\n \u003cp\u003ewhere R is an alkyl group C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e. In this reaction, ionic species are SiO\u003csup\u003e\u0026minus;\u003c/sup\u003e, OH\u003csup\u003e\u0026minus;\u003c/sup\u003e, NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e and H\u003csup\u003e+\u003c/sup\u003e. H\u003csup\u003e+\u003c/sup\u003e concentration is much smaller than OH\u003csup\u003e\u0026minus;\u003c/sup\u003e concentration in basic solution. Thus, SiO\u003csup\u003e\u0026minus;\u003c/sup\u003e, OH\u003csup\u003e\u0026minus;\u003c/sup\u003e and NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e are predominately present in solution. This results in hydrolysed products to condensed with each other to form spherical shaped nanoparticles. Thus, hydroxyl concentration in the solution has a significant task to control hydrolysed product and form spherical silica particles. Besides, ammonia was used as catalyst to adjust the hydroxyl concentration throughout the reaction system. Moreover, ammonia is alkalescent and partially disintegrates to control hydroxyl concentration in the solution[30]. Therefore, a higher amount of hydroxyl was produced when ammonia concentration increased, and a greater number of hydroxyl groups were substituted with TEOS alkoxy groups. Thus, it can be concluded that higher ammonia concentration is suitable to obtain larger size spherical shaped silica nanoparticles.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e3.3. EDX Analysis:\u003c/h2\u003e\n \u003cp\u003eFigure 4 (a-b) shows the elemental mapping images and EDX spectrum of the Stober synthesized silica thin films. The EDS spectrum displays a strong signal related to occurrence of oxygen and silicon. Further, from the quantitative results obtained from the EDX measurement the atomic wt% of silicon and oxygen was found to be 79.9% and 20.1% respectively. The elemental mapping images depicted in Fig.\u0026nbsp;4(a) confirm the existence of Si and O in the sample. Thus, the purity of the silica nanoparticle samples is greater than 99.9% as traces of no other impurity elements have been observed in the EDX spectrum. Absence of impurity in this data signifies that the EDX result of the synthesized silica nanoparticles are consistent with the XRD results obtained.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003e3.4. UV- visible Analysis:\u003c/h2\u003e\n \u003cp\u003eFigure 5 illustrates the UV-visible absorbance spectra of silica thin films at different ammonia concentrations in the 200\u0026ndash;700 nm range. As shown in Fig.\u0026nbsp;5 (a), the absorbance peak exhibited a clear shift in the UV\u0026ndash;Vis range i.e. 290 nm -300 nm with changes of their particle size. The wavelength corresponding to the absorbance peaks blue shifted with the increase of silica nanoparticle sizes i.e. because of larger numbers of neighbouring atoms and silanol groups. Moreover, the rearrangement of components in silica thin films as well as an increase in disorder, number of vacancies, and particle size could be responsible for this blue shift. Such various significant features of silica thin films cause a considerable increase of the optical band gap energy [31]. Thus, the following Tauc equation was used to determine the band gap of the silica thin film sample using the UV\u0026ndash;visible absorption spectra [32].\u003c/p\u003e\n \u003cdiv id=\"Equ1\"\u003e\n \u003cdiv id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$$\\:\\left(\\alpha\\:h\\nu\\:\\right)=A{(h\\nu\\:-Eg)}^{n}$$\u003c/div\u003e\n \u003cdiv\u003e6\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eThis equation represents \u0026alpha;, h\u0026nu;, A, Eg, and n as the absorption coefficient, the incident photon energy, proportionality constant, optical band gap, and dimensionless parameter, respectively. For an indirect band gap energy, n\u0026thinsp;=\u0026thinsp;2, but for a direct band gap energy, n\u0026thinsp;=\u0026thinsp;1/2. By using Eq.\u0026nbsp;(6), a graph between \\(\\:{\\left(\\alpha\\:h\\nu\\:\\right)}^{2}\\)and h\u0026nu; was plotted as shown in Fig.\u0026nbsp;5 (b) and the optical energy band gap of samples S1, S2, and S3 are observed at 3.50 eV, 3.57 eV, and 3.67 eV respectively. Generally, a higher density of metallic cations is typically found in pristine samples, which contributes to the abundance of independent electrons in the crystal lattice. These electrons gain energy and increase their kinetic energy when a light beam strikes the sample. The current flow of the material increases and the band gap energy decreases as a result of these electrons jumping to the conduction band. However, the material density is decreased in amorphous silica, which lowers the amount of free electrons in the lattice and raises the energy gap between the valence and conduction bands with increasing the energy bandgap [33]. Another notable characteristic has been observed in silica thin film samples i.e. the absorbance spectra become extremely low at 450 nm, indicating that any radiation above 450 nm is not absorbed by the silica thin films. This suggests that the films block UV radiation and only permit light in the visible spectrum to get through. Thus, this is the one of advantage of silica thin films that block the ultraviolet part [34].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e3.5. Wettability Analysis:\u003c/h2\u003e\n \u003cp\u003eThe static water contact angle of silica thin films was determined by gently dropping 1\u0026micro;L of distilled water onto the coated surface using a micro-syringe. For each measurement the droplets were replicated at four different places on the coated substrate. The water contact angle (WCA) was measured by employing goniometer, which captured a picture of the droplet instantly as it was placed on the surface.\u003c/p\u003e\n \u003cp\u003eFigure 6 (a-d) shows the wetting behaviour of uncoated and silica coated glass substrates annealed at 400\u0026deg;C temperature for 1 hr. The method for contact angle analysis was first calibrated by comparing the water contact angles of glass, which is found to be around 48\u0026deg;. The water droplet depicts higher contact angle on an uncoated glass, whereas after the deposition of silica nanoparticles, water contact angle (WCA) shows low contact angle. Further it is well understood that the thermal treatment of silica coated glass substrates results in change in surface roughness which leads to super-hydrophilic surface. Thus, it has been found that on the flat glass surface, the water contact angle was observed as 48\u0026deg;, however the silica coated glass displays super-hydrophilicity with WCA around 4.5\u0026deg;. This can be explained based on the presence of high energy OH bonds i.e. the hydrophilicity of silica thin films is due to the density of surface hydroxyl groups. Good hydrophilicity is produced when the surface hydroxyl groups generate hydrogen bonds with water molecules, which is responsible for altering the wetting state from Cassie-Baxter state (superhydrophobic) to Wenzel state (superhydrophilic) [35]. Hydroxylation occurs when acetone solvent is used for surface treatment. A significant improvement in the variation of contact angles can be observed from a statistical analysis of all the samples. In Fig.\u0026nbsp;6 (e), it has been observed that with increasing in particle size, contact angle also increased from 4.5\u003csup\u003e\u0026omicron;\u003c/sup\u003e to 15.3\u003csup\u003e\u0026omicron;\u003c/sup\u003e. This is due to correlation in particle size, surface energy and contact angle. The variation in nanoparticle size and contact angle could be caused by the surface energy. The surface to volume ratio increases with decreasing nanoparticle size, increasing surface free energy and causing the contact angle to decrease. In the case of larger particles, the opposite occurs [36]. Hence it can be concluded that, the wetting behaviour of any surface depends on both surface chemistry and surface topography.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this current work, silica thin films were synthesized by Stober process with variation in ammonia concentration followed by spin coating on glass substrates. The XRD result confirmed the broad amorphous diffraction peak centred at 2θ\u0026thinsp;=\u0026thinsp;24.1\u003csup\u003eο\u003c/sup\u003e. Morphological analysis depicts spherical shaped silica nanoparticles which increased from 200 nm \u0026ndash; 350 nm with increasing in ammonia concentration. From elemental mapping and EDX spectrum the atomic wt% of Si and O was found to be 79.9% and 20.1%, respectively, which confirms the presence of Si and O without impurities. The band gap of silica thin films was increased from 3.50 eV to 3.67 eV with increase in ammonia concentration. It was confirmed by the wettability studies that the wetting characteristics are dependent on surface morphology, as the contact angle increased from 4.5\u003csup\u003eο\u003c/sup\u003e to 15.3 \u003csup\u003eο\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors have contributed to the methodology and experiment. K. Pradhan: Investigation, Methodology, Formal analysis, Software, Validation, Writing\u0026ndash; original draft, S.P. Ghosh: Formal analysis, Writing\u0026ndash; review \u0026amp; editing; T. Badapanda, J. Ray: Resources, Visualization, Supervision, Writing- review \u0026amp; editing. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors express their sincere thanks to Dr. S.Anwar, Sr.Principal Scientist, Materials Chemistry Department, Institute of Minerals and Materials Technology, Bhubaneswar Odisha, for contact angle measurement. measurements. The authors are thankful to C V Raman Global University, Odisha for providing financial support to carry out the work.\u003c/p\u003e\u003ch2\u003eData Availability:\u003c/h2\u003e \u003cp\u003eThe data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eA. Luthfiah, Y. Deawati, M. L. Firdaus, I. Rahayu, D. R. Eddy, Science and Technology Indonesia 6, 3(2021)\u003c/li\u003e\n\u003cli\u003eP. U. Nzereogu, A. D. Omah, F. I. Ezema, E. I. Iwuoha, A. C. Nwanya, Hybrid Advances 4, (2023)\u003c/li\u003e\n\u003cli\u003eS. Hern\u0026aacute;ndez, D. Hidalgo, A. Sacco, A. Chiodoni, A. Lamberti, V. Cauda, E. Tresso, G. Saracco, Physical Chemistry Chemical Physics 17, (2015)\u003c/li\u003e\n\u003cli\u003eY. Kobayashi, J. Imai, D. Nagao, M. 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Singh, Journal of Applied Physics 103, 8(2008) .\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":"","lastPublishedDoi":"10.21203/rs.3.rs-4823922/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4823922/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAn effective sol-gel technique that yields conformal coatings with amorphous silica (SiO\u003csub\u003e2\u003c/sub\u003e) is the St\u0026ouml;ber method. In the present manuscript, we have synthesis SiO\u003csub\u003e2\u003c/sub\u003e thin film using the solgel-based Stober method and deposited on glass substrates by spin coating technique. We have examined the impact of ammonia concentration during the synthesis process of silica thin films on the structural, morphological, optical, and wetting characteristics. XRD analysis confirmed the presence of amorphous silica phase for all thin film samples. Elemental analysis illustrated the presence of Si and O element in the sample without any impurity. Moreover, the average diameter of silica nanoparticles has been obtained by utilizing Field emission scanning electron microscopy (FESEM). The variation of optical bandgap of silica thin films prepared at different ammonia concentration was investigated via UV-Vis spectrum. The wetting properties of silica thin films have been studied from the contact angle measurement concerning to variation in ammonia concentration.\u003c/p\u003e","manuscriptTitle":"Exploration of impact of ammonia concentration on the surface morphology, optical and wettability performance of SiO2 thin film","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-26 16:13:28","doi":"10.21203/rs.3.rs-4823922/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":"9b29122d-bd8c-408e-a72a-01383baf76bc","owner":[],"postedDate":"August 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-10-02T09:53:51+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-26 16:13:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4823922","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4823922","identity":"rs-4823922","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}