View of THE SYNTHESIS AND CHARACTERIZATION TECHNIQUES OF TIN OXIDE (SnO2) BASED POLY COMPONENT METAL OXIDE NANOCOMPOSITES: A CRITICAL REVIEW

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VOLUME: 10, Special Issue 02, (IC-IMAF-2023) Paper id-IJIERM-X-II, January 2023 16

THE SYNTHESIS AND CHARACTERIZATION TECHNIQUES OF TIN OXIDE (SnO2) BASED POLY COMPONENT METAL OXIDE NANOCOMPOSITES: A CRITICAL REVIEW

1Parveen Rathi, ²Manoj Kumar, ³Rajesh Sharma

1Research Scholar, ECE Deptt., Om Sterling Global University, Hisar, Haryana (India)

2Associate Professor, ECE Deptt., Om Sterling Global University, Hisar, Haryana (India)

3Assistant Professor, Physics Deptt., MNS Govt. College, Bhiwani, Haryana (India)

Abstract- In the present scenario, nanoscience is a unique field of research due to its enhanced properties in different areas of research such as Medical, Defense, Physics, Chemistry, and Electronics, etc. At the nanoscale, the particles have unique advanced properties as compared to their bulk because of the huge surface area volume ratio and quantum size effect. The mass properties of materials frequently change theoretically with nano ingredients. Among other metal oxides, the SnO2 metal oxide nanomaterials have advanced applications such as in semiconductors, the electrode of the battery at low cost.

To create it more useful of SnO2, So completing the requirement of industry and users the SnO2 based nanocomposites is knee interest of today researchers. The design nanocomposites material adheresto both the property of host and guest materials. However, at present time various synthesis techniques are utilized by researchers but solvo-chemical methods such as the modified co-presentation method are suitable for researchers because of their cost-effective and user-friendly techniques. In the present work, the authors are making a critical review affecting parameters such as Temp.(temperature) and Ph for SnO2

nanoparticles for synthesis techniques and described the various characterization tools (Method) such as XRD, FITR, UV Visible SEM and TEM.

Keywords: - SnO2 nanocomposites XRD, FITR, UV-visible SEM and TEM.

1 INTRODUCTION

Nanostructured materials are obtained by reducing the size of particles at nanoscales (1- 100 nm). Large methods as categories in the "Top-down & Bottom-Up Approach" are employed to synthesize nanomaterials according to the applicant's wishes. Even thougha greater number of nanomaterials are still at the research centre at the stage of development, a significant number of these are currently becoming commercialized.

However, Nanoparticles are found in the natural environment in various forms, including all those produced by photochemical and volcanic eruptions as well as those produced by algae and plants. Metal nanoparticles, for example, are futuristic particles to enhance advanced technology. The authors are of due to the fact that multifunctional properties (such as A.C& D.C. and magnetic characteristics) contrast to their bulk counterpart eg.

Titanium dioxide (Titania) and Zinc oxide (ZnO2). Among metal Oxide nano-structured materials, the rare earth metal doped nanostructured materials are attracted researchers because of their photoluminescent properties and futuristic energy source with green technology.

Furthermore, nanoparticles offer a large number of potential applications, including textiles, cosmetics, and medical applications enabling targeted drug delivery to a specific (Particular) part of the body. Nanoparticles also can be structured into layers on surfaces, providing a high surface area and better action, which is important for a wide range of potential applications, like impetuses. Made nanoparticles are usually not products in and of themselves, but rather serve as raw materials, fixes, or added compounds in existing items. Nanoparticles are found in a wide range of consumer products, including cosmetics, and their unique features may affect their toxicity. In some applications (for example, within a composite or affixed to a surface), nanoparticles will be fixed, whereas in others they will be free or suspended in fluid. Whether they are fixed or free will also have a major effect on their potential health, safety, and environmental consequences.

2 CLASSIFICATION OF NANOMATERIALS

Materials are classified as 1 dimension (1D) (e.g., surface films), 2 dimensions (2D) (e.g., strands or fibres), or 3 dimensions (3D) based on their morphology and dimensionality (e.g.,

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particles). They occur in tubular, spherical, and irregular shapes and can be solitary, fused,aggregated, or agglomerated. Nanotubes, quantum dots, dendrimers, and fullerenes are common examples of nanomaterials. Nanomaterials are also used in nanotechnology and exhibit physical-chemical properties that are distinct from ordinary substances (i.e., carbon nanotube, silver nano, fullerene, carbon nano, photocatalyst, silica). According to Siegel, Nanostructured materials are classified as 0 dimensional (0D), 1 dimensional(1D), 2 dimensional(2D), 3 dimensional(3D) nanostructures.

Figure 1 Nanomaterials Classification (a) zero-dimensional spheres and clusters (b) one-dimensional nanofibers, wires, and rods (c) two-dimensional films, plates, and

networks (d) three-dimensional nanomaterials

Nanomaterials are materials with ultra-fine grain sizes (less than 50 nm) or dimensionality of less than 50 nm. As shown in Figure 1, nanomaterials can be made from different modulation dimensionalities: zero (atomic clusters, filaments, and cluster assemblies), one (multilayers), two (ultrafine-grained overlayers or buried layers), and three (nanophase materials consisting of equiaxed nanometre-sized grains).

3 PROPERTIES OF TIN OXIDE (SnO2) NANOPARTICLE

Tin oxide (SnO2) nanoparticles are available as faceted diamagnetic oxide nanostructures with a large surface area.Sn (Tin) belongs to Period 5, Block Pin the periodic table. and oxygen belongs to Period 2, Block P in the periodic table. The chemical symbol of Tin oxide is SnO2 and Electronic configuration Tin [Kr] 4d¹⁰ 5s² 5p² Oxygen [He] 2s² 2p⁴. In SnO2 Tin element contain 78.76% and oxygen 21.21%.Tin oxide has the form of a white powder with a spherical morphology The density of tin oxide is 6.95 g/cm³ and molar mass is 150.71 g/mol. The melting point and boiling point of tin oxide is 1630°C and 1800-1900°C respectively.

4 SYNTHESISMETHODS

Synthesis methods for material design are essential for controlling the size and functioning of materials. [1] There are a variety of synthesis methods available, some of which are explained in the sections below.

4.1 Precipitation Method

Modified Emulsion Precipitation Method, Solvothermal Synthesis/ Hydrothermal Synthesis, Sol-Gel Method Aerogel Methods.

4.2 Modified Emulsion Precipitation Method

This method has the significant advantage of preventing particle agglomeration in individual bubbles. In the future, this will enable processing at unusually low temperatures. [2,3]

Precipitation pathways for multi-component oxides must be arranged in such a way that an intimate combination of atoms arises during precipitation and chemical homogeneity is maintained during further processing to get the most out of the technique. These challenging procedures, such as emulsion co-precipitations, are usually carried out with sample precursors that do not affect emulsion stability but have a tendency to precipitate at

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different rates, resulting in partial phase segregation. This approach is utilized to build high thermal stability emulsion systems. In the emulsion system, each droplet contains only a few atoms. Reactive species must interact between droplets to form a stable precipitate.

According to the Einstein-Smoluchowski equation, the normal rate of particle formation is faster than the comparable rate of exchange between droplets Nucleation and development in emulsions are inhibited along these lines, avoiding the organization of enormous particles, in contrast to that inhomogeneous arrangement. Multisurfactants aid in the formation of a thermally stable emulsion and the control of droplet size. Other compounds work as steric particle stabilizers once the water has been removed. The emulsions were made by mixing the oil phase (Cyclohexane or n-heptane) with threitol surfactants and octan-1-ol as a cosurfactant before particle dispersion by filtration or decantation of the organic phase. Water was added to the system in stoichiometric proportions, then vigorously mixed until a translucent emulsion formed. The emulsion was dropped into alkoxide alcohol solutions and agitated for many hours. The residue was picked up in acetone to disintegrate the micelles after the solvents were removed in dis-person. After drying and calcining the solid product obtained after decantation of the organic phase, it was converted into a nanocrystalline spinal.

4.3 Solvothermal Synthesis

Hydrothermal synthesis is a method for crystallizing and producing hydrous ceramic materials directly from solutions by using a single heterogeneous phase reaction in aqueous media at high temperatures and pressures. [4] The synthesis provides a low-temperature, direct route to oxide powder with a tight size circulation that keeps the calcination phase at a safe distance. A fluid nucleation model is followed by the instrument of an aqueous response. The-orris of substance balance, compound energy, and thermodynamic parameters of watery systems under aqueous conditions are provided as point-by-point standards. The process for warming metal salts, oxides, or hydroxides as an answer of suspension in fluid at controlled temperature and weight for roughly 20 hours is applied to clay powders. In a hydrothermal process, the temperature is typically between the boiling point of water (1000 c) and the critical temperature (Tc= 374 c), but the pressure is greater than 100 kPa. To remove ions from the solvent and other contaminants, the product is rinsed with de-ionized water. Ceramic nanoparticles that are fairly well dispersible are generated after dehydration. pH, reaction temperature, reagent concentrations, and duration will all affect the particle size and stability of the result. Because the mechanics of hydrothermal reactions are distinct, the corresponding process conditions may differ significantly. Hybridizing hydrothermal synthesis with microwaves, electrochemistry, ultrasound, mechanochemistry, and optical radiation can also improve it.

4.4 Sol-Gel Method

In the creation of multi-component oxide ceramics, the Sol-Gel process has various advantages. During solid-state calcinations, the early synthesis of a gel gives a high level of homogeneity and minimizes the needs for atomic diffusion. [5] Furthermore, metal alkoxides, which are liquids or volatile solids that may be easily refined to yield exceptionally pure oxide precursors, are frequently used in the process. This is an important element in electro ceramic synthesis. However, the metal alkoxides' relatively high pricing may make them unsuitable for some applications, and the release of considerable volumes of alcohol during the calcination stage necessitates safety precautions.

After preparing a solution of the relevant precursors (metal salts of metal-organic compounds), hydrolysis and condensation are used to convert the solution into homogenous oxide (gel). The oxide product is obtained by drying the gel and then calcining it. In addition, alkoxides are combined together in alcohol to make multi-component oxides.

Acetates and other components for which no alkoxides are available are introduced as salts.

The alkoxides, additional water, and alcohol are all hydrolysed under strict temperature, pH, and concentration controls. By using aerosol techniques, ultrafine particles can be created in two ways. The first step involves producing a supersaturated vapour from a

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reactant and then homogeneous nucleation (gas-to-particle conversion). The second step entails the formation of liquid droplets, which are then heated to become solid particles (liquid-to-particle conversion). The final option is to use it to make multi-component materials.

The most prevalent procedures for liquid-to-solid conversion are spray pyrolysis and spray drying. The process begins with the preparation of a metal precursor (sol) solution, which is then atomized into droplets and deposited in a furnace. The final product is obtained by evaporation of the solvent, drying, precipitation, gas-phase reactions, and pyrolysis inside the furnace. Spray drying is similar to spray pyrolysis, with exception of the type of precursors used and the use of colloidal dispersion particles. This approach yielded evenly spherical granules with diameters ranging from submicron to millimetres.If the liquid contains colloidal nanoparticles (primary particles), the granules that form nanostructure granulated powders also contain nanoparticles. Spray drying might then be used to consolidate nanoparticles into submicron spherical granulates that can then be crushed into microscopic forms.

The composition of final particles is determined by the ratio of reactants dissolved in the first solution. The average size and size distribution in the initial solution are mostly determined by the size of the atomized droplets and the precursor concentrations.

Precursor properties, carrier gas flow rate (i.e., time spent in the hot zone), and temperature will all be considered.

4.5 Aerosol Methods

This method is also known as a gas phase method. It is thought to be practical and cost- effective in large-scale industrial multi-component material production.

4.6 Citrate-Gel Method

Metal ions in precursor solutions are stabilised by an organic network in citrate-gel techniques, resulting in fine oxide powders following a heating step. [7] They can make multi-component formulations with excellent homogeneity and stoichiometry control.

Between the C-O ligands of citric acid and metal ions, poly-chelates are used in these procedures. When heated with polyfunctional alcohol, the chelate undergoes poly esterification. The chelating process occurs during the evaporation of the precursor solution comprising metallic salts and citric acid in the citrate technique. Further heating results in the formation of a viscous resin and a hard translucent, glassy gel. In the early stages of the creation of this stiff system, mixtures of different metal ions become immobilised. During succeeding calcinations, the probability of segregation into distinct oxide compositions is considerably reduced.

4.7 Penchini Method

The Penchini method [8] is remarkably similar to the citrate-gel method, with the exception that metal nitrates are dissolved in alcohol rather than water.

4.8 Low-Temperature Combustion Synthesis Method

For the synthesis of ultra-fine powders, the low-temperature combustion synthesis (LCS) technique has proven to be a unique, very simple, time-saving, and energy-efficient route.

[9] This method is based on the gelling and subsequent combustion of an aqueous solution containing metal salts and some organic fuels, resulting in a voluminous and fluffy product with a large surface area. Starting components contain oxidizing metal salts such as metal nitrates and a combination agent (fuel) such as citrate acid, polyacrylic acid, or urea.

Citrate acid is more extensively employed since it may be used as a chelating agent as well as a reductant/fuel agent. The initial mixture's molar ratio of fuel to nitrates has a significant impact on calcination conditions and the properties of the generated crystallites.

Homogeneous crystalline spinel powders with a nanoscale primary particle size are generated by adjusting the CA/NO3 ratio and calcination temperature.

The sol-gel method provides considerable benefits in numerous procedures, but the cost of precursor materials and metal alkoxides is higher than in other methods, and the proper

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precursors are not always available. For organic-inorganic hybrids, sol-gel processing has been crucial, and the development of novel ceramic nanoparticles is highly useful and may generate fine ceramic nanoparticles. The same principle of hydrolysis of solution species is used in hydrothermal synthesis as it is in sol-gel synthesis, but without the calcinations step. This method has not yet gained the same level of popularity as the sol-gel method.

Emulsion precipitation methods are useful for creating single component nanoscale ceramic particles, but they are less so for multi-component ceramics. This is due to the fact that different precursors have varying hydrolysis rates and it is difficult to remove (co-) surfactants, which are employed to maintain emulsions stable.

Polymer techniques that use homogenous amorphous solid intermediates may produce target nanoparticles with less phase segregations. For the preparation of certain multi- component nanocrystalline ceramics, all of these approaches have been successful.

5 VARIOUS CHARACTERIZATION METHODS

The quantity and homogeneity of the product, as well as the performance of the resulting materials, can be used to assess the success of the chemical synthesis of ceramic nanoparticles. The most frequent metrics of porous media are the mean pore size, porosity, surface area, and the more complex pore size distribution. Fitting experimental data to one of several models and reporting the model's associated property yields the values of these measures. Table 1 lists the most often used characterisation methods.

5.1 Scanning Electron Microscopy (Sem)

The Scanning Electron Microscope shows the material's surface morphology. [10] It creates an electron beam in a vacuum. Electromagnetic condenser lenses collimate the beam, an objective lens targets it, and electromagnetic deflection coils scan it across the sample's surface. The first imaging approach involves gathering free secondary electrons from the material. A scintillation substance that creates light flashes from the secondary electrons is used to find them.A photomultiplier tube is used to determine and amplify the light flashes.

An image identical to what would be seen with an optical microscope can be created by matching the sample scan location with the generated signal.

The electron beam worn to probe the sample is generated by the electron gun of a Scanning Electron Microscope. A cathode emits electrons, which are accelerated by passing through electrical fields and focussed on a first optical picture of the source. The initial solve factors in the solution and performance of a scanning electron microscope are the shape and size of the visible source, current, and beam acceleration. Spot welded on metal posts is a bent tungsten wire filament with a diameter of roughly 100 micrometers. These posts are embedded in a ceramic holder and stretch out to enable electrical connections on all sides. The filament is normally heated by sending an electric current through it. The ideal filament temperature for thermionic electron emission is roughly 2427 degrees Celsius. The Wehnelt cylinder receives an accelerating voltage that ranges between 500 and 50,000 Volts DC.

Figure 2 Electron gun for SEM

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VOLUME: 10, Special Issue 02, (IC-IMAF-2023) Paper id-IJIERM-X-II, January 2023 21 5.2 Transmission Electron Microscopy (TEM)

Particle form, size, and morphology are studied using transmission electron microscopy (TEM). [11,12] A beam of photographic film (see electron microscope) or a CCD camera is used in the TEM imaging technique. Thermionic discharge, similar to the cathode in a cathode ray tube or field emission, produces electrons that are accelerated by an electric field and focussed onto the sample by electrical and magnetic fields. The scanning transmission electron microscope (STEM) is a type of TEM in which the beam can be guided over the material to generate the image.

5.3 Image Formation in the Transmission Electron Microscopy

Although the intensity of the transmitted beam is still impacted by the volume and density of the material through which it passes, a crystalline substance interacts with the electron beam mostly through absorption. Diffraction intensity is determined by the orientation of atom planes in a crystal structure.

5.4 X-Ray Diffraction (XRD)

The X-ray Powder Diffraction (XRD) technique is a useful analytical tool for characterising and identifying unknown crystalline minerals. [13,14] Figure 2 depicts the X-ray Diffraction Unit. To ensure that all crystallographic directions are sampled (specifically selected) by the beam, samples are evaluated as powders with grains in random orientations. When the Bragg criteria for constructive interference are met, a reflection occurs, with a relative peak height that is about equal to the number of grains in the favoured orientation. This approach generates X-ray spectra that reveal the unknown's structural fingerprint. In addition, crystalline mixtures are studied, and comparative peak heights of several materials are employed to provide semi-quantitative abundance estimations.

The structural information of a thin coating on the surface is obtained using a glancing X-ray beam. Changes in peak location that convey structure-state information (e.g., order- disorder transitions, exsolution) or compositional variation (solid solution) can also be easily detected. For the identification of unknown crystalline minerals, the whole ASTM powder diffraction file is conveniently accessible online. The peak is immediately determined by data reduction methods.

5.5 Fourier Transform Infrared Spectroscopy (FTIR)

The vibrational stretch frequency of metal-oxygen bonding is revealed using Fourier Transform Infrared Spectroscopy (FTIR). [16] A continuum source of light is used to create light over a broad range of infrared wavelengths for Fourier Transform Infrared Spectroscopy. A half-silvered mirror splits the light from this continuous source into two streams. Light is directed onto the material of interest in FTIR Spectroscopy, and the intensity is measured using an infrared detector. The resultant graph shows the Fourier Transform of the intensity of light as a function of wave number when the intensity of light is measured and plotted as a function of the position of the movable mirror. A Michelson Interferometer is utilised as a radiation source. Figure 3 depicts the fundamental structure of the device. The phenomenon of multiple internal reflections is exploited to increase the sensitivity of semiconductors. The edges of the sample are polished with this process, and the light is sent in at an angle. The light bounces back and forth inside the sample, around 30–50 times. This improves sensitivity by around a factor of 30–50, allowing researchers to quantify the absorption of molecules in less than one monolayer on a surface.

Figure 4 FTIR UV-Vis Absorption Spectroscopy

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Absorption of UV-Visible Light UV absorbance of crystalline ceramic and amorphous gel samples heated at different temperatures is measured using spectroscopy. [17] Many molecules are photosensitive to visible and ultraviolet light. The absorbance of a solution is directly proportional to the beam loss, i.e. it grows as the beam loss increases. The route length b and the concentration c of the absorbing species are directly proportional to absorbance. Beer's Law asserts that A =bc, where is a proportionality constant, and said absorptivity. Different molecules absorb different wavelengths of light. Different absorption bands, such as structural groups inside the molecule, will be visible in an absorption spectrum.

Electrons are jumped from their ground state to an excited state when a molecule or atom absorbs energy. The atoms of a molecule can rotate and vibrate in relation to one another. Different energy levels are also present in these rotations and vibrations, which can be called the pinnacle of each electronic level. The activation of the outer electron causes UV or visible radiation to be absorbed.

6 CONCLUSION

The overall study concludes that the particle's size and morphology area function of used synthesis techniques and existing parameters such as temperature and Ph of reaction. The SnO2 nanostructured materials are rutile structures with tetragonal symmetry. The many tools for characterization were helpful to examine the structural, optical, electrical, and magnetic properties of synthesized materials for further applications in various fields based on their upcoming properties.

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