SnO2 Powders Research Articles

Surface Defect Generation on SnO2 Nanoparticles Using High-Energy Ball Milling for H2S Gas Sensor Applications

Hydrogen sulfide (H2S) is a highly toxic and dangerous gas with a flammable and corrosive nature, making the development of reliable gas sensors for its detection vital. This study investigated the enhancement in H2S gas sensing performance of commercial SnO2 powders after high-energy milling. SnO2 powders were subjected to high-energy milling for 30, 60, and 90 min and then were characterized using advanced techniques to evaluate their morphology, chemical composition, and crystallinity. The response of a pristine SnO2 gas sensor, and ones where the SnO2 was milled for 30, 60 and 90 min, were 2.46, 2.27, 3.01, and 1.98, respectively, to 10 ppm H2S at 300°C. Thus, the H2S gas sensing results revealed that the SnO2 powders milled for 60 min exhibited the highest sensing performance. This improvement in H2S sensing performance was attributable to the reduced particle sizes achieved through the high-energy milling process, which increased the surface area and created defects on the surface of the SnO2 particles, thereby enhancing the interaction between the gas molecules and sensor material. The smaller morphological size of the particles and surface defects subsequently promoted the resistance modulation crucial for H2S gas detection. This study demonstrates that high-energy ball milling can effectively boost the gas-sensing features of SnO2 powders. The findings can provide guidance for enhancing the gas-sensing capabilities of other resistive sensors.

Doping Effects of Metal-Doped Tin Oxide Nanoparticles Used As Carbon-Free ORR Catalysts for Polymer Electrolyte Fuel Cells

Polymer electrolyte fuel cells (PEFCs) are an important energy device for the realization of a hydrogen society. However, a longer service life is essential for the further spread of PEFCs. Currently, catalyst ( platinum supported on carbon, Pt/C) is the most mainstream cathode one. But, it has durability issues due to carbon degradation during high potential sweeps. As an alternative material to carbon, tin oxide (SnO2) is attracting attention due to its electrical conductivity and chemical stability. It has already been reported that Pt/SnO2 catalysts using SnO2 doped with antimony (Sb), niobium (Nb), tantalum (Ta), etc., and they exhibit high durability. However, they have a lower Pt electrochemical surface area (ECSA) and oxygen reduction mass activity (MA) compared to Pt/C. Therefore, further improvement of ECSA and MA is required for the practical use of Pt/SnO2. Other dopants may improve catalyst activity, so it’s worth checking the effects for doping other elements. In this study, a total of 20 metal-doped tin oxides (M-doped SnO2) were synthesized. Pt metal-doped tin oxide (Pt/ M-SnO2) was prepared by loading platinum onto the synthesized M-doped SnO2, and its catalytic performance was evaluated. M-doped SnO2 nanoparticles were synthesized by the solvothermal method. Tin chloride pentahydrate, metal chlorides as doping materials, methanol, and tetramethylammonium hydroxide solution were mixed and stirred to form a precursor. The solution was placed in a Teflon-coated stainless steel autoclave and heat treated. After 12 hours, the reactants were washed and dried to obtain M-doped SnO2. Pt/M-SnO2 was prepared using the polyol method. The prepared M-doped SnO2 powder was mixed and dispersed in a mixed solvent of ethylene glycol and water, then platinum chloride hexahydrate was added and stirred overnight. The solution was then heated at 120°C for 2 hours to produce the platinum nanoparticles on the SnO2 surface. The activity evaluation of the prepared catalysts was carried out at a rotating disk electrode in a three-electrodes cell system. The electrolyte was 0.1 M HClO4, the counter electrode was a platinum wire electrode, the reference electrode was a reversible hydrogen electrode, and the working electrode was a glassy carbon disk (GCD) electrode. Catalyst ink was dripped onto the working electrode and dry by spinning at 300 rpm for 1 hour. Measurements were performed by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). From the obtained peak, ECSA and MA values were calculated. Among the Pt/M-doped SnO2, Pt/Mo-SnO2 and Pt/Sb-SnO2 showed specific peaks. In the CV, the peak area of the lower left part corresponding to the H2 adsorption was greatly enlarged in Pt/Mo-SnO2. As a result, Pt/Mo-SnO2 recorded the highest ECSA value (74.4 m2g-1 -Pt), exceeding that of Pt/pure-SnO2 (24.1 m2g-1 -Pt). In the LSV, the onset potential of the Pt/Sb-SnO2 peak shifted to the higher side than Pt/pure-SnO2. As a result, Pt/Sb-SnO2 recorded the highest value of Mass Activity (93.5 A g-1 -Pt), which is much higher than that of Pt/pure-SnO2 (17.1 A g-1 -Pt). The catalytic performance is significantly changed by doping metallic elements into tin oxide crystal.

Enhancing the antioxidant, antimicrobial resistance, and anticancer potency of plant-mediated SnO2 and Se doped P-SnO2 NPs by Justicia adhatoda: An in vitro approach

In this work, plant-mediated SnO2 NPs were green synthesized using Justicia adhatoda plant leaf extract, and the synthesized SnO2 powder was doped with Se nanorods at various concentrations (10 %, 20 %, and 30 %). The synthesized sample was characterized using XRD, HRSEM, SEM-EDAX, SEM-EDS, TEM, UV–Vis, and FTIR spectra. Furthermore, we investigated the antibacterial activity of P-SnO2 NPs and Se-doped P-SnO2 NPs at various concentrations of selenium (10 %, 20 %, and 30 %) against three gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) and one gram-positive bacteria (Staphylococcus aureus) using the agar disc diffusion method. Furthermore, an antioxidant activity (DPHH) and cytotoxicity study (HepG2) were performed. Morphological analysis was used to identify the P-SnO2 nanoparticle shape as spherical in shape and the Se nanoparticle shape as a nanorod. The TEM image reveals that 30 % of the Se-doped P-SnO2 NPs exhibit an inner core structure. The TEM image used to identify the size of P-SnO2 NPs is 64 nm, and the Se nanorod is 4.06 nm. The 30 % Se-doped P-SnO2 NPs demonstrate good bacterial activity compared to P-SnO2, and 10 % and 20 % Se-doped P-SnO2 nanoparticles. Antioxidant activity: 30 % Se-doped P-SnO2 NPs show an excellent IC50 value compared to others; the IC50 values of 30 % Se-doped P-SnO2 NPs are 33.71 µg/ml. The cytotoxicity of 30 % Se-doped P-SnO2 NPs exhibits an IC50 value of 121 µg/ml against the HepG2 cell line. So, it is very useful for medicinal applications.

H2S gas sensing properties of ZnO–SnO2 branch–stem nanowires grown on a copper foil

ZnO–SnO2 branch–stem nanowires were fabricated on a Cu foil using a chemical vapor deposition system through a two-step process. Firstly, SnO2 NWs were synthesized directly on a Cu foil substrate by evaporating SnO powder as a source material. Then, the as-synthesized SnO2 NWs were used as templates for the growth of ZnO–SnO2 branch–stem NWs. The effect of growth time on the growth of the SnO2 NWs on the Cu foil was studied. The gas sensing properties of the SnO2 NW and ZnO–SnO2 branch–stem NW devices were studied using various toxic gases at different temperatures. Both devices exhibited high sensitivity, high selectivity, fast response and recovery times, and stability toward H2S gas. Compared to the pristine SnO2 NW device, the ZnO–SnO2 branch–stem NW device exhibited higher sensitivity and faster response rate toward H2S. Finally, the gas sensing mechanism was also discussed.

Effects of Au Addition to Porous CuO2-Added SnO2 Gas Sensors on Their VOC-Sensing Properties

The effects of Au addition on the acetone response of Cu2O-added porous SnO2 (pr-Cu2O-SnO2) powders, which were synthesized by ultrasonic spray pyrolysis employing polymethyl methacrylate microspheres as a template, were investigated in this study. The 3.0 wt% Au-added pr-Cu2O-SnO2 sensor showed the largest acetone response among all sensors. In addition, the magnitude of the acetone response was much larger than those of the ethanol and toluene responses. The catalytic activities of these gases over Au-added pr-Cu2O-SnO2 powders were also examined to clarify the key factors affecting their acetone-sensing properties. The Au addition increased the complete oxidation activity of all gases, and the complete oxidation activity of acetone was much higher than those of ethanol and toluene. These results indicate that the oxidation behavior during the gas-diffusion process in the sensitive Au-added pr-Cu2O-SnO2 layer of the sensors is quite important in enhancing the acetone-sensing properties.

Photocatalytic performance of (Zn,Me)–SnO2 nanoparticles (Me= Nb5+ or W6+) under UV light for efficiently degradation of organic dye pollutants

In this study (Zn,Nb)-doped SnO2 and (Zn,W)-doped SnO2 were synthetized using chemical route by calcination at 600 °C/2 h and milling at 500 rpm/1 h to verify its behavior as a photocatalyst. The powders showed high surface area: 57.1 m2/g for (Zn,Nb)-doped SnO2 and 74.3 m2/g for (Zn,W)-doped SnO2, both showed 10–25 nm of average diameter and rutile crystalline phase after morphological and structural characterizations. UV–vis spectroscopy indicated a band gap of 3.53 eV for (Zn,Nb)–SnO2 and 3.35 for (Zn,W)–SnO2. The photocatalytic activity was verified through the decomposition of Rodhamine B (RhB) aqueous solution under ultraviolet light radiation of 9W. After 120 min the efficiency of (Zn,Nb)–SnO2 was 68.5 % and for (Zn,W)–SnO2 was 71.1 %. Using a UV-lamp of 11W the efficiency in photodiscoloration of RhB aqueous solution increased to 83.2 % with (Zn,W)-doped SnO2 powder in a shorter irradiation time (90 min), indicating its potential use as nanostructured photocatalyst ceramic powder.

Constructing heterojunction-induced oxygen vacancies of N-doped carbon-encapsulated Sn/SnOx microplates for boosting lithium storage capability

Heterogeneous Sn/SnOx@N-doped carbon (Sn/SnOx@NC) microplates with oxygen vacancies evolved from plate-like SnO powders are successfully fabricated, in which SnO powders are converted into Sn, SnO2, and Sn2O3 phases by rationally sintering and are perfectly in situ encapsulated by polyaniline-derived NC layer. By elaborately constructing the particular structure, high discharge specific capacity of 730.4 mAh/g and capacity retention ratio of 98.3 % after 110 cycles at 0.1 A/g are realized for optimal Sn/SnOx@NC composite electrode. Benefiting from enhanced electronic conductivity and Li+ ions diffusion kinetics, the assembled cell delivers reversible discharge specific capacity of 487.3 mAh/g at 1.0 A/g after 500 cycles. First principles calculation and in/ex situ characterization reveal that in situ formed heterostructure with oxygen vacancies and NC layer synergistically improve interfacial charge transfer and reaction reversibility to promote lithium storage capability. Therefore, fabricating Sn/SnOx@NC microplates may provide a practical strategy to design heterogeneous and oxygen-deficient Sn-based anode materials for high-performance lithium-ion batteries.

Quantum confinement effects on the structural and optical properties of nanostructured tin oxide powder

Nanostructured Tin oxide powders, prepared by chemical precipitation method, exhibit interesting structural and optical properties at nanoscale dimensions. Structural characterization confirmed the formation of pure nanostructured SnO2 powders with average crystalline grain size of 54.4[Formula: see text]nm calculated with relative uncertainty of 1.62%. The optical properties of nanoSnO2 powder performed by using transmittance and photoluminescence measurements reveal high transparency and multi-photon emissions in visible and ultraviolet regions. The different photon emissions are attributed to radiative transitions via oxygen vacancies, Sn interstitials, Sn substitutional and dangling bonds. The lower wavelength value corresponded to the absorption edge peak indicating the good quantum confinement of nanostructured SnO2 powder. The larger optical band gap, calculated through transmittance measurements, confirms the quantum confinement effects. The presence of quantum confinement and native point defects in nanostructured SnO2 powders can contribute to enhancing photon emissions process. This result may offer inherent advantages over conventional materials for photonic quantum information technology. The sustained photon emission at room temperature, indicates that SnO2 nanoparticles could be useful in room temperature quantum computing and can maintain the delicate quantum states required for computation at higher temperatures.

Investigation of the structural and photometric properties of SnO2-incorporated polycarbazole nanocomposite for emissive layer material

Polycarbazole (PCz) has recently piqued the interest of scientists and researchers for its potential usage in the Flextronics industry owing to its flexibility and chemical stability. The goal of incorporating Tin oxide (SnO2) into PCz is to increase the photoluminescence intensity. The oxidizing agent FeCl3 was used in the presence of the carbazole monomer and SnO2 powder to synthesize the PCz/SnO2 nanocomposite. X-ray diffraction (XRD) analysis was used to conduct structural studies. Morphological and elemental analysis of as-synthesized PCz/SnO2 nanocomposite were performed using a Field Emission Scanning Electron Microscope (FE-SEM). The photoluminescence intensity of PCz/SnO2 nanocomposite is increased, indicating that it might be an efficient emissive layer material for optoelectronic devices.

Characterizations of Cr3+- doped SnO2 Powders Via a Hydrolysis Method

In this work, the effect of annealing temperature and Cr3+ concentration on the structural and optical properties of the SnO2 host crystals has been investigated. The Cr-doped SnO2 samples were synthesized by a simple hydrolysis method, using SnCl4.5H2O as the host precursor and CrCl3.6H2O as the source of dopant. X-ray diffraction and Raman scattering spectra analysis revealed a tetragonal rutile structure of Cr3+-doped SnO2 samples. The Cr3+ concentration and annealing temperature have no influence on the lattice parameters of the SnO2 crystals, whereas affected the appearance and intensity of the Raman modes. The optical properties of the synthesized samples were explored by photoluminescence (PL) and photoluminescence excitation (PLE) analysis. Interestingly, besides the emission peaks related to the SnO2, emission transitions within Cr3+ ions in the octahedral field of SnO2 were observed.

Green Synthesis of Mixed ZnO-SnO2 Nanoparticles for Solar-Assisted Degradation of Synthetic Dyes

In this work, ZnO, SnO2, and their mixed ZnO-SnO2(25%) nanoparticles (NPs) were successfully green synthesized in a straightforward manner with a low-cost and environmentally friendly approach using a banana peel extract. The synthesized nanophotocatalysts were characterized using various techniques including FTIR, XRD, UV-Vis, TEM, SEM, BET, PL, EDS, and TGA. The characterization results showed that the ZnO and SnO2 powders were crystallized in a hexagonal wurtzite and rutile-type tetragonal structures, respectively, and their mixed ZnO-SnO2(25%) NPs contain both structures. Also, it was found that the addition of SnO2 into the ZnO structure reduces the PL intensity of the latter, confirming better separation of electron/hole pairs. The average particle size of a ZnO-SnO2(25%) NP photocatalyst was found to be 7.23 nm. The cationic dyes methylene blue (MB) and crystal violet (CV) as well as the anionic dyes naphthol blue black (NBB) and Coomassie brilliant blue R 250 (CBB) were employed as model dyes to assess the dye removal efficiencies of the biosynthesized nanophotocatalysts under sunlight. In all cases, the mixed ZnO-SnO2(25%) NP photocatalyst showed much better photocatalytic activity than individual photocatalysts. The degradation percent of dyes using ZnO-SnO2(25%) NPs ranged between 92.2% and 98%. The efficient photocatalytic activity of ZnO-SnO2(25%) NPs is attributed to the effective charge separation and reduced electron/hole recombination rate. The kinetic study results conformed to a pseudo first-order reaction rationalized in terms of the Langmuir–Hinshelwood model. Furthermore, the results showed that the ZnO-SnO2(25%) NP photocatalyst is highly stable and could be recycled several times without a noticeable reduction in its catalytic activity towards dye removal.

Synergistic effects of bimetallic Pd-Au(alloy)/SnO2 nanocomposites for low temperature and selective hydrogen gas sensors

In view of the explosive nature of hydrogen gas, the demand for detection is increasing. Although Pd-based chemiresistive sensors are gaining much attention in hydrogen detection, it is easily oxidized at high temperatures, leading to the deterioration of sensing performance. To address this issue, we synthesized bimetallic Pd-Au alloy nanoparticles (NPs) and mixed them with SnO2 powder for improving the hydrogen sensing performance. The response of the bimetallic Pd-Au(alloy)/SnO2 nanocomposites (NCs) sensor toward 100 ppm hydrogen was 72.78 which is 7 times higher than that of the pure SnO2 sensor at a relatively lower working temperature of 150°C. Furthermore, when compared to other interfering gases, the sensor revealed high selectivity for hydrogen gas. The enhanced hydrogen sensing performance was attributed to the synergistic effect arising from the formation of a heterojunction interface between Pd-Au alloy and SnO2 NPs and the decomposition and absorption of hydrogen molecules by Pd-Au alloy NPs.

Room-temperature SnO2-based sensor with Pd-nanoparticles for real-time detection of CO dissolved gas in transformer oil

SnO2 and Pd nanoparticles (NPs) were synthesized by hydrothermal method and sol-gel, respectively. A paste formed by tin dioxide NP and PVDF was deposited as thick film on alumina substrates through screen printing method and decorated with Pd on surface. The morphology and structure of the samples were investigated by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy. The SEM images show SnO2 nanoparticles with rod shapes and 10–15 nm of diameter size and Pd spherical nanograins with 15–35 nm of diameter. XRD analysis identifies rutile structure for SnO2 powder and cubic structure for Pd NP. To investigate the gas sensing property of the SnO2:Pd nanostructured composite, the electrodes were immersed in an insulating mineral oil, in a closed system where different gas concentration of monoxide carbon (CO) were injected into the headspace and then dissolved into oil, according to Ostwald coefficient. All measurements were carried out at room temperature using a concentration range from 50 to 500 ppm (in headspace). The electric characterization showed that our SnO2-based sensor had change its resistance in a lower concentration of dissolved gas, ∼13.3 ppm of CO, into the mineral oil, indicating its potential use for real time monitoring of transformers.

Room-Temperature Hydrogen-Sensitive Pt-SnO2 Composite Nanoceramics: Contrasting Roles of Pt Nano-Catalysts Loaded via Two Different Methods

Soluble noble metal salts are widely used for loading noble metals as nano-catalysts in many applications. In this paper, Pt-SnO2 composite nanoceramics were prepared from SnO2 nanoparticles and H2PtCl6 using two Pt loading methods separately: for the solution reduction method, a H2PtCl6 solution was added to a suspension of SnO2 and zinc powder to form Pt on SnO2 nanoparticles, and for the impregnation method, Pt was formed from H2PtCl6 in the course of sintering. Although a series of samples prepared using both Pt loading methods showed a solid response to H2 at room temperature, the ones prepared using the solution reduction method exhibited much better room-temperature hydrogen-sensing characteristics. For two samples of 0.5 wt% Pt and sintered at 825 °C, the response value for the sample prepared using the solution reduction method was 9700 to 1% H2–20% O2-N2, which was much larger than the value of 145 for the sample prepared using the impregnation method. Samples prepared using the two Pt loading methods have similar microstructures characterized via XRD, FESEM, EDS, TEM, and HRTEM. However, the residual chlorine content in those using the impregnation method was higher than those using the solution reduction method according to the analysis. It is proposed that the striking difference in room-temperature hydrogen sensing characteristics among samples prepared using these two different Pt loading methods separately resulted from their different chlorine removal processes. This study demonstrates the importance of a proper method for loading noble metals from their soluble salts as nano-catalysts in many applications.

Synthesizing of SnS2 photocatalyst from SnO2 powders by thermal sulfurization with varying temperature (400 °C and 500 °C) and time

SnS2 from SnO2 powders was successfully produced by the thermal sulfurization method to obtain pure SnS2 powders by varying the sulfurization temperature and time. XRD analysis confirmed pure hexagonal SnS2 powders at 400 and 500 °C after 24 h of sulfurization. Grain size analysis in SEM indicated that the average grain size of powders synthesized at 400 °C and 500 °C were 1 and 11 μm, respectively. The band gap values of the obtained powders at 400 and 500 °C was determined by UV–vis spectroscopy as 2.26 eV and 2.24 eV, respectively. The photoelectrochemical analysis of the SnS2 photoelectrode produced at 500 °C revealed a flat band potential of −0.50 V, a charge carrier density of 1.49 × 1020 cm −3 and photocurrent density of 2.5 μA/cm2 at 0 V vs SCE. These results indicated that SnS2 synthesized for the first time by the thermal sulfurization technique from SnO2, which was a simple and cheap technique, was a promising candidate to be used as a photocatalysts.

Synthesis of SnO2 nanowires using thermal chemical vapor deposition with SnO powder and their application as self-powered ultraviolet photodetectors

We report on the performance of self-powered ultraviolet (UV) photodetectors composed of SnO2 nanowire (NW) networks. SnO2 NWs with a length of several hundred micrometers can be synthesized by thermal chemical vapor deposition (CVD) using SnO powder as the raw material, which has the advantages of a low process temperature and no requirement for a reducing agent. Based on the characterization results obtained through synchrotron X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM), we determined the growth behavior of SnO2 NWs via a vapor-liquid-solid mechanism with Au nanoparticles. The NW growth switched from an initial in-plane growth to subsequent vertical growth, forming NW cotton. This was started at a process temperature of 600 ℃ and optimized at 800 ℃. Moreover, the XRD and TEM results indicate that the NWs mainly grew in the form of SnO2, although the formation of SnO NWs was also possible. Metal−SnO2 NW−metal type photodetectors were fabricated, and their photoresponsivity to UV light in the range from 200 to 400 nm was investigated. The device exhibited a photo-to-dark current ratio of ∼2.17 × 106 at an applied bias of 10 V and 254 nm UV exposure. A maximum responsivity of about 1100 A/W was estimated at a wavelength of 270 nm, and the cutoff edge wavelength appeared around 350 nm. In particular, the self-powered photoresponse at nominal zero bias was ∼1.23 nA. The results of this study support the idea that SnO2 NWs are promising candidates for self-powered deep-UV photodetectors and that thermal CVD using SnO powder is suitable for synthesizing SnO2 NWs at temperatures as low as 700 °C.

Dipole behavior in thin film heterostructure composed of Er-doped SnO2 and GaAs: Influence of polarization bias, temperature and stray light

The heterostructure system GaAs/SnO2 is built by resistive evaporation of Er-doped SnO2 powder on the top of GaAs semi-insulating substrate. The SnO2 powder comes from the drying of SnO2 sol-gel solution. The possible formation of dipoles in this heterostructure is investigated by the thermally stimulated depolarization current (TSDC) technique, and the possibilities for dipole formation are explored, such as the EL2 defect in the GaAs side, oxygen vacancies and Er ions in the SnO2 layer. The dipole relaxation activation energies are found in the range 0.2 eV to 0.3 eV, in good agreement with the ionization energies of these defects. The main TSDC bands: 213 meV with peak of −298 pA, for positive bias, and 218 meV with peak of 128 pA for negative bias, are modified by stray (room) light, which may correspond to the second ionization level of oxygen vacancies in SnO2, which are excited by the room lights and do not return to the original orientation.

SnO2-Based NO2 Gas Sensor with Outstanding Sensing Performance at Room Temperature.

The controlled and efficient formation of oxygen vacancies on the surface of metal oxide semiconductors is required for their use in gas sensors. This work addresses the gas-sensing behaviour of tin oxide (SnO2) nanoparticles for nitrogen oxide (NO2), NH3, CO, and H2S detection at various temperatures. Synthesis of SnO2 powder and deposition of SnO2 film is conducted using sol-gel and spin-coating methods, respectively, as these methods are cost-effective and easy to handle. The structural, morphological, and optoelectrical properties of nanocrystalline SnO2 films were studied using XRD, SEM, and UV-visible characterizations. The gas sensitivity of the film was tested by a two-probe resistivity measurement device, showing a better response for the NO2 and outstanding low-concentration detection capacity (down to 0.5 ppm). The anomalous relationship between specific surface area and gas-sensing performance indicates the SnO2 surface's higher oxygen vacancies. The sensor depicts a high sensitivity at 2 ppm for NO2 with response and recovery times of 184 s and 432 s, respectively, at room temperature. The result demonstrates that oxygen vacancies can significantly improve the gas-sensing capability of metal oxide semiconductors.

Correlation of micro-structure with the opto-electronic properties of the sol-gel derived powder Sn1-xCdxO2 nanoparticles

Powdered cadmium substituted tin oxide (Sn1-xCdxO2) nanoparticles (NPs) with various Cd2+ ion concentrations (0%–30%) were synthesized via sol-gel route. The X-ray diffraction (XRD) and high resolution transmission electron microscopic (HRTEM) results justified the nanocrystallinity of the samples as the mean crystallite sizes were found within 16 nm–38 nm. The Williamson – Hall (W – H) analysis was employed for determining the relation between the lattice strain and crystallite size of the powder NPs. The monotonous decrease of lattice strain is consistent with the increase of crystallite size by increase in Cd2+ substitution concentration. The substitution of Sn4+ with Cd2+ caused an increase of particle size with the increase of Cd2+ concentration. The energy dispersive X-ray spectroscopic (EDS) studies indicated the presence of cadmium ion in the Cd-substituted SnO2 powder NPs. Further, the Fourier-transform infrared (FT-IR) spectra of the powder samples registered the distinct absorbance band dips highlighting the atomic vibrations. The optical absorption (OA) spectra revealed that the band gap energies (Eg) decreased with the increase in Cd2+ substitution levels. The positron annihilation lifetime (PAL) spectroscopic analysis based on the vacancy type defects which were present in abundance in the powder NPs and played vital roles to modify their properties. The photo-induced luminescence properties were studied by fluorescence (FL) spectroscopy based on defects and/or oxygen vacancies associated with the emission transitions. The results suggested the feasibility of tailoring the characteristics of Cd-substituted SnO2 NPs synthesized through sol-gel route for various technological applications.

Experimental Spectroscopic Data of SnO2 Films and Powder

Powders and films composed of tin dioxide (SnO2) are promising candidates for a variety of high-impact applications, and despite the material’s prevalence in such studies, it remains of high importance that commercially available materials meet the quality demands of the industries that these materials would most benefit. Imaging techniques, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), were used in conjunction with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to assess the quality of a variety of samples, such as powder and thin film on quartz with thicknesses of 41 nm, 78 nm, 97 nm, 373 nm, and 908 nm. In this study, the dependencies of the corresponding Raman, XPS, and SEM analysis results on properties of the samples, like the thickness and form (powder versus film) are determined. The outcomes achieved can be regarded as a guide for performing quality checks of such products, and as reference to evaluate commercially available samples.