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. 
                        more » 
                        « less   
                    
                            
                            Synthesis, Spectroscopic Characterization and Applications of Tin Dioxide
                        
                    
    
            Metal oxides are useful for the detection and sensing of combustible and toxic gases, and for use in lithium batteries and solar cells. The present study focuses on the spectroscopic investigation of commercial and in-house laboratory synthesized tetragonal tin dioxide (SnO2), aimed at studying its physical and chemical properties at nanoscale levels and in bulk. We have investigated the pure powder form and thin films prepared on two different types of substrate, silicon and UV-Quartz, each with five different thicknesses (i.e. 41, 78, 96.5, 373, and 908 nm). Raman spectroscopy with two different laser excitation wavelengths, namely 780 and 532 nm, has been used to investigate the various SnO2 vibrational modes. Thermal effects on the primary vibrational features in the Raman spectra have been studied in the range 30–170 °C. X-ray diffraction (XRD) spectra have been recorded to confirm the rutile structure of tin dioxide and to obtain information on the spherical grain particle size of SnO2 with EDS analysis for the thin film samples. Scanning Electron Microscope (SEM) images have been recorded in order to understand the morphology of the particles of SnO2 at the nanoscale level. In addition, FT-IR spectra have been obtained to study the IR-active vibrational modes for the bulk and thin film samples on the two substrates. Moreover, UV-VIS spectra have been employed to determine the energy band gap for the SnO2 film samples by an efficient process facilitated by a Tauc plot technique utilizing an in-house developed python script. 
        more » 
        « less   
        
    
                            - Award ID(s):
- 1659224
- PAR ID:
- 10209713
- Editor(s):
- Mubarak, Nabisab M.; Walvekar, Rashmi; Arshid, Numan; and Khalid, Mohammad
- Date Published:
- Journal Name:
- Chapter in Book: Contemporary Nanomaterials in Material Engineering Applications
- Page Range / eLocation ID:
- 285-316
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
- 
            
- 
            Fullertubes are tubular fullerenes with nanotube-like middle section and fullerene-like endcaps. To understand how this intermediate form between spherical fullerenes and nanotubes is reflected in the vibrational modes, we performed comprehensive studies of IR and Raman spectra of fullertubes C90-D5h, C96-D3d, and C100-D5d. An excellent agreement between experimental and DFT-computed spectra enabled a detailed vibrational assignment and allowed an analysis of the localization degree of the vibrational modes in different parts of fullertubes. Projection analysis was performed to establish an exact numerical correspondence between vibrations of the belt midsection and fullerene headcaps to the modes of nanotubes and fullerene C60-Ih. As a result, we could not only identify fullerene-like and CNT-like vibrations of fullertubes, but also trace their origin in specific vibrational modes of CNT and C60-Ih. IR spectra were found to be dominated by vibrations of fullerene-like caps resembling IR-active modes of C60-Ih, whereas in Raman spectra both caps and belt vibrations are found to be equally active. Unlike the resonance Raman spectra of CNTs, in which only two single-phonon bands are detected, the Raman spectra of fullertubes exhibit several CNT-like vibrations and thus provide additional information on nanotube phonons.more » « less
- 
            One of the most significant drawbacks of metal oxide (MOS) based chemiresistive gas sensors is the requirement of high operating temperature (250–450 °C), which results in significant power consumption and shorter lifetime. To develop room temperature (21±2 °C) MOS chemiresistive gas sensors, the sensing performance of different MOS nanostructures (i.e., tin (IV) oxide (SnO2) nanoparticles (NPs), indium (III) oxide (In2O3) NPs, zinc oxide (ZnO) NPs, tungsten trioxide (WO3) NPs, copper oxide (CuO) nanotubes (NTs), and indium tin oxide (In90Sn10O3 (ITO)) NPs) were systematically investigated toward different toxic industrial chemicals (TICs) (i.e., nitrogen dioxide (NO2), ammonia (NH3), hydrogen sulfide (H2S), carbon monoxide (CO), sulfur dioxide (SO2) and volatile organic compounds (VOCs) (i.e., acetone (C3H6O), toluene (C6H5CH3), ethylbenzene (C6H5CH2CH3), and p-xylene (C6H4(CH3)2)) in the presence and absence of 400 nm UV light illumination. Sensing performance enhancement through photoexcitation is strongly dependent on the target analytes. Under 400 nm UV photoexcitation at 76.0 mW/cm2 intensity, room temperature (21±2 °C) NO2 sensing was readily achieved where SnO2 NPs exhibited the highest sensor response (S = 474.4 toward 10 ppmm (parts per million by mass)) with good recovery followed by ZnO NPs > In2O3 NPs > ITO NPs. Meanwhile, indirect bandgap n-type WO3 NPs showed limited NO2 sensing performance under illumination, whereas p-type CuO NTs showed relatively good sensing response. The most significant improvements in SnO2 compared to other MOS nanoparticles might be attributed to the highest number of photogeneration electrons, which rapidly reacted with adsorbed species to enhance the reaction kinetics. WO3 NPs showed a unique sensing response toward aromatic compounds (e.g., ethylbenzene and p-xylene) under UV illumination, where maximum sensitivity was achieved under 36 mW/cm2 irradiation. Changing light intensity from 0.0 to 36.4 mW/cm2, WO3 showed 15.4-fold and 6.3-fold enhancement in sensing response toward 25 ppmm ethylbenzene and 100 ppmm p-xylene, respectively. 400 nm optical excitation has a limited effect on the sensing performance toward CO, SO2, toluene, and acetone.more » « less
- 
            SnO2 is a prototypical transparent conducting oxide that finds widespread applications as transparent electrodes, gas sensors, and transparent thin-film devices. Hydrogen impurities in SnO2 give rise to unintentional n-type behavior and unexpected changes to conductivity. Interstitial H (Hi) and H at an oxygen vacancy (HO) are both shallow donors in SnO2. An O–H vibrational line at 3155 cm−1, that can be produced by a thermal anneal at 500 °C followed by a rapid quench, has been assigned to the Hi center and is unstable at room temperature on a timescale of weeks. An IR absorption study of the decay kinetics of the 3155 cm−1 O–H line has been performed. The disappearance of Hi upon annealing has been found to follow second-order kinetics. Measurements of the decay rate for a range of temperatures have determined an activation energy for the diffusion of interstitial H in SnO2. These results provide fundamental information about how unintentional hydrogen impurities and their reactions can change the conductivity of SnO2 device materials in processes as simple as thermal annealing in an inert ambient.more » « less
- 
            Carbon is a common contaminant in oxide thin film semiconductors that can affect important properties such as the work function, surface chemistry, and electrical conductivity. In this work, carbon impurities in sputtered anatase titania (TiO2) and indium tin oxide (ITO) thin films were investigated using Raman and optical transmission spectroscopy. Annealing in a rough vacuum yielded carbon precipitates, which have characteristic disordered and graphitic carbon Raman signatures. Irradiation by a 532 nm laser in the ambient air was effective in removing the carbon precipitates; in the case of ITO, no trace of carbon could be observed in the Raman spectra following irradiation. The combination of vacuum annealing and laser irradiation could provide a practical means for reducing carbon impurities in thin films.more » « less
 An official website of the United States government
An official website of the United States government 
				
			 
					 
					
 
                                    