Search

Abstract Indium tin oxide powders containing different amount of tin were prepared using a facile water based sol-gel procedure. The structural and microstructural properties have been analysed with X-ray diffractometer, FTIR-spectroscopy, XPS, TEM and EDX analysis. The nanocrystalline powders were used to fabricate Taguchi design based thick film sensors and their low concentration ammonia sensing (30 ppm) performance were evaluated in the operating temperature range of 200–400 °C. Indium tin oxide sensor having 20 wt% tin oxide showed the optimum response, ∼61% for 30 ppm ammonia at operating temperature of 300 °C. Pd incorporation led to a significant enhancement in sensing response (∼82%) at the same condition. A good sensing response (∼43%) was also observed even at very low ∼ 3 ppm of ammonia concentration. The interference of other gases was almost insignificant. The sensor was stable as reflected from the observation of negligible decrease in the sensing performance of sample up to 90 days period. The sensing mechanism for enhancement has also been explained. Graphical abstract Image 1 Highlights • Different compositions of indium tin oxide were prepared using a unique procedure. • I 80 T 20 O sensor reveals optimum sensing response, ∼61% towards 30 ppm NH 3 at 300 °C. • 1 wt% Pd incorporation enhanced the sensitivity by ∼20%. • The sensor can detect very low concentration of NH 3 with reproducible performance. • It is also very stable and selective. [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]

Abstract: Nanostructured indium tin oxide (ITO) films were deposited on silica glass by sol–gel dipping method from salt derived PVA based aqueous precursor. The films were cured at 250°C, 350°C, 450°C, 600°C, 700°C and 900°C and characterized by XRD, SEM, AFM techniques to observe heating effect on nanostructured feature. Nanocluster sizes were determined by TEM study. Different crystal phases of ITO were existed in the temperature range 250–900°C. Quantum confinement behavior of the nanoclusters was observed for their size being near Bohr radius. Absorption, band gap and photoluminescence behavior of the nanstructured ITO films supported excitonic transitions due to the formation of electron hole pair generated by interaction of electromagnetic radiation. [Copyright &y& Elsevier]

• Using a unique gel calcination procedure 4 at% La loaded ITO nanopowder prepared. • Its sensing response was ~65% in 10 ppm ethanol but base resistance quite high. • 1wt% Pd & 0.5 wt% Sb loading enhanced response ~20% with acceptable resistance. • Stable and able to detect ~1 ppm of ethanol with fast response and recovery time. • Reproducible sensing performance with minimum interference. The present work reports on a novel resistive ppm level ethanol sensor, prepared from nanocrystalline lanthanum loaded indium tin oxide (ITO) impregnated with palladium and antimony additives. A simple unique gel calcination process was adapted to synthesize the nanocomposite powders from their water based precursor salts. This was followed by detailed material characterizations through X-ray diffractometer, FESEM, TEM, EDX and XPS analyses. Fabricated Taguchi type sensor with an optimum concentration of Pd exhibited an excellent sensing performance towards a wide concentration range of (1–100 ppm) ethanol vapour. The sensor showed ~87% sensing response for 10 ppm ethanol vapour at an operating temperature of 300 °C. Even at 1 ppm concentration, ~53% response was observed with fast response and recovery time. The sensing action has been elucidated as the catalytic oxidation of ethanol to carbon di oxide over the La loaded ITO surface layer that resulted in electron transfer to the indium tin oxide site. In addition, synergistic effect of palladium and antimony enhanced the sensing performance as well as reduced the base resistance of the sensor by chemical/electronic sensitization and increasing carrier ion concentration respectively. Comparatively low resistance, negligible cross sensitivity, quick response/recovery time and good long term stability makes the sensor suitable for deployment in practical applications. [ABSTRACT FROM AUTHOR]