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Cd-Sn oxide nanocomposites were synthesized by sol-gel method from precursor sol containing Cd:Sn = 2:1 and 1:1 mol ratio. Instead of coprecipitation, a simple novel gel calcination route was followed. Cd (NO). 4HO and SnCl. 5HO were used as starting materials. Gel was calcined at 1050 °C for 2 h to obtain nanocomposites. XRD analysis reveals the presence of orthorhombic, cubic CdSnO along with orthorhombic, hexagonal CdSnO phases in both the composites. SEM and TEM studies indicate the development of nanocomposites of different shapes suggesting different degrees of polymerization in precursor sol of different composition. UV-Vis absorption spectra show a blue shift for both the composites compared to bulk values. Decrease of polarization with frequency, dipole contribution to the polarization, and more sensitivity to ethanol vapor were observed for the nanocomposite derived from precursor sol containing Cd:Sn = 2:1 mol ratio. [ABSTRACT FROM AUTHOR]

4 wt% La-doped SnO nanocrystalline powders impregnated with 0.5-1.5 wt% Pd were synthesized by a facile sol-gel method. The powders characterized through XRD, TEM, EDX as well as XPS analyses were used for the fabrication of sensors. 0.5 wt% SbO was incorporated in each case to reduce the resistance of sensors. The gas response studies revealed a large enhancement in low concentration (1-100 ppm) ethanol vapour sensing at comparatively lower operating temperature (300 °C) on 1.0 wt% Pd incorporation. The response observed (~86 %) for 10 ppm vapour was ~16 % greater compared to 4 wt% La-doped SnO with improved response (2 s) and recovery (15 s) times. The high ethanol vapor response at comparatively lower operating temperature of this sensor is attributed to the combinatorial effect of alkalescence of SnO due to La-doping and widening of depleted region by spill-over process of PdO present on SnO surface. [ABSTRACT FROM AUTHOR]

Nanocrystalline undoped and lanthanum(III) doped (2, 4 and 6 at%) tin oxide powders were synthesized using sol-gel processing from their water based precursor sols. Microstructures and surface morphologies of all powders were characterized using X-ray diffractometer, BET surface area, UV-Visible spectrophotometer, scanning and transmission electron microscope along with energy dispersive X-ray diffractometer. XRD and UV-Vis spectral analyses revealed decrease of tin oxide crystallite size on La(III) doping. 4 at% La(III) doped powder showed ~5 nm average particle size and ~42 m/g surface area respectively. A systematic comparison study revealed that sensors made from 4 at% La(III) doped SnO powder exhibited optimum ethanol vapor sensing performance at operating temperature, 350 °C (response ~70 % for 10 ppm ethanol) with excellent response and recovery times. Even for very low concentration ethanol vapour (1 ppm) response observed was ~53 %. A possible mechanism for enhancing sensitivity on La(III) doping has been discussed. [ABSTRACT FROM AUTHOR]

• A ternary nanocomposite containing 3 wt% rGO decorated ZnO-SnO 2 was prepared using a facile sol-gel procedure. • Pristine ZnO-SnO 2 nanocomposite sensor exhibited ~ 60% response towards 10 ppm acetone at operating temperature of 300°C. • ~3wt% rGO addition enhanced the response upto ~ 91% for 10 ppm acetone as well as operating temperature reduced to 150°C. • rGO decorated sensor was capable to detect very low concentration (~1 ppm) of VOCs with fast response and recovery time. • The sensor shows reproducible performance over time with negligible sensing response in other reducing gases. [Display omitted] A ternary p-n-n heterojunction has been prepared by introducing reduced graphene oxide (rGO) in ZnO-SnO 2 nanocomposite and its ppm level volatile organic compounds (VOCs) sensing properties have been exploited. Using a simple, facile sol-gel process, initially, ZnO-SnO 2 nanocomposites containing different concentrations of ZnO and SnO 2 were prepared and subsequently this was followed by rGO incorporation. The as-synthesized powders were well characterized through XRD, FTIR, Raman spectroscopy, FESEM, TEM, and XPS analyses. The sensing study revealed that, the ternary nanocomposite sensor delineated ~91% n-type sensing response towards ~10 ppm acetone gas at an optimum working temperature of 150 °C. Even it could sense ~1 ppm acetone with appreciable sensing response of ~71%. Additionally, the sensor displayed fast response (~10 s) and recovery time (~100 s) suitable for detection of multiple pulses in short time duration. It also exhibited a considerable ~65% sensing response towards ~10 ppm ethanol at 150 °C. These superior sensing performances of rGO decorated ZnO-SnO 2 nanocomposite illustrated with band structure modification. Our results indicated that, the fabricated rGO decorated ZnO-SnO 2 sensor, with remarkable high sensing response, minimum interference from other toxic, inflammable gases and profound long term stability, could be considered as a prolific candidate for real time detection of low concentration VOCs in versatile commercial applications. [ABSTRACT FROM AUTHOR]

Abstract: Sol–gel based nanostructured Cr(III)-doped indium tin oxide (ITO) films (In:Sn:Cr=84.6:9.4:6.0) deposited on silica glass were cured at 350°C, 450°C, 600°C, 700°C and 900°C. EDX, absorption spectra and TEM images confirmed formation of Cr(III)-doped ITO nanoclusters close to Bohr radius of ITO. Excitonic and phonon interactions were studied by absorption, photoluminescence (PL) and Raman spectra. The photon energy between the satellite peaks of PL spectra predicted phonon vibrations. Strong hybridization between s–p-states of host and d-states of Cr(III) resulted in stable exciton–phonon coupling as revealed from excitonic and lattice phonon vibrations. Soft room temperature ferromagnetism was observed in the films. [Copyright &y& Elsevier]

The present paper reports on a unique eco-friendly bio-synthesis process of tin oxide using water extract of soaked kabuli chickpea seeds as natural binder. The structural, microstructural and CO sensing properties of the newly synthesized tin oxide were compared with those of conventional sol–gel and sonochemical processes. XRD results of the bio-synthesized material revealed the formation of single tetragonal phase of SnO 2 similar to sol–gel and sonochemical processes. The bio approach led to the formation of finer nanoparticales with a higher specific surface area ∼ 60 m2 /gm compared to the others. The average sizes of tin oxide nanoparticles as observed from TEM images were about 35 nm, 15 and 6 nm for the sonochemical, sol-gel and biosynthesis respectively. These tin oxide powders were used to fabricate Taguchi based sensors and their CO sensing performance were evaluated. The biosynthesized tin oxide sensor showed ∼53% sensing performance for 30 ppm CO which was better than sol-gel (∼44%) or sonochemical (∼42%) tin oxides operating at similar condition. The reported results suggest that the biosynthesis is a promising cost effective method to prepare nanocrystalline SnO 2 for sensing application. Image 1 • Pure tin oxide powder of average particle size ∼6 nm was prepared using water extract of kabuli chickpea seeds. • The structural and morphological properties of this were compared with sol-gel and sonochemical processes. • The sensor fabricated from biosynthesized tin oxide revealed the best sensing performance, ∼53% on exposure of 30 ppm CO. • This sensor was stable and able to detect very low concentration (∼3 ppm) of CO with reproducible performance. • The mechanism for the formation of nanoparticles and better sensitivity has been illustrated. [ABSTRACT FROM AUTHOR]

• An improved rGO incorporated WO 3 based electrochromic film was developed using a facile sol-gel dip-coating procedure. • 5wt% rGO composition demonstrated the maximum electrochemical performance along with 50% transmittance modulation. • ∼ 45% enhancement in the switching response time and a significant improvement in coloration efficiency were also obtained. • The observed better electrochemical cyclic stability of rGO-WO 3 film was analyzed using ex-situ XRD analysis. • The EIS study of pristine and rGO decorated films revealed enhanced charge transfer on incorporation of rGO. In the present work, an improved electrochromic thin film has been developed with faster color switching time on incorporation of rGO in WO 3 film. Here, pristine WO 3 and rGO-WO 3 (rGO concentration varying from 1–7wt%) based nanocomposite electrochromic films were fabricated on ITO coated glass substrate, by utilizing a facile sol-gel dip-coating technique. Detailed structural and morphological analyses of the films were carried out using XRD, FESEM, TEM and Raman Spectroscopy. Assimilating the electrochromic properties of all the films showed that, 5wt% rGO incorporated WO 3 film gave a maximized electrochemical performance with minimum degradation in optical transmittance. The film also exhibited an optical modulation of ∼ 50% and a better switching response having coloration time (t c) ~ 5.3 s and bleaching time (t b) ~ 6.2 s as compared to the pristine film (t c ~ 9.6 s, t b ~ 10.4 s). Incorporation of rGO also resulted in an enhancement of coloration efficiency from ∼ 81 to ∼ 386 cm2/C. The Electrochemical Impedance Spectroscopy (EIS) analysis of pristine and rGO loaded film clearly revealed better charge transfer on incorporation of rGO. The cyclic stability study exhibited ∼ 25% deterioration in optical transparency of the bare WO 3 film which was < 10% for the rGO impregnated film. An ex-situ XRD analysis demonstrated that a crystal dislocation occurring in pristine WO 3 sample was responsible for the same. [Display omitted]. [ABSTRACT FROM AUTHOR]