S.S. Suryavanshi

Enhanced acetone sensing performance of nanostructured Sm2O3 doped SnO2 thick films

Abstract In the present work, we synthesized Sm 2 O 3 doped SnO 2 in order to prepare a selective acetone sensor with fast response, quick recovery and good repeatability. Pure as well as 2 mol.%, 4 mol.%, 6 mol.% and 8 mol.% Sm 2 O 3 doped SnO 2 nanostructured samples were synthesized by using a co-precipitation method. The characterization of the samples was done by thermogravimetric and differential thermo-gravimetric analysis (TG-DTA), X-ray diffraction (XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy dispersive analysis by X-rays (EDAX), high resolution scanning electron microscopy (HR-TEM), selected area X-ray diffraction (SAED), Brunauer-Emmet-Teller (BET) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy techniques. The gas response studies of liquid petroleum gas, ammonia, ethanol and acetone vapor were carried out. The results showed that Sm doping systematically lowered operating temperature and enhanced the gas response and selectivity for acetone. The response and recovery time for 6 mol.% Sm 2 O 3 doped SnO 2 thick film at the operating temperature of 250 °C were 15 and 24 s, respectively.

Performance evaluation of galvanostatically deposited nickel oxide electrode for electrochemical supercapacitors

Nanostructured nickel oxide (NiO) electrode has been prepared using electrochemical work station operated on galvanostatic mode in supercapacitor application. Crystalline cubic structure and nanoplate-type of morphology of synthesized NiO electrode was confirmed from X-ray diffraction and scanning electron microscopy analysis respectively. The wettability study was tested by contact angle measurement, which reveals hydrophilic nature of NiO electrode with contact angle of 59°. The presence of nickel and oxygen characteristic bands in EDAX and XPS spectrum has corroborated the NiO formation. The supercapacitive properties of NiO electrode were tested by cyclic voltammogram (CV) in 1xa0M aqueous Na2SO4, KOH, NaOH electrolytes within the potential range of −u20091.1 to 0.9xa0V, 0 to 0.4xa0V and −u20091.2 to 0.4 respectively. The CV study demonstrates maximum specific capacitance of 481.16 Fg−u20091 for 1xa0M Na2SO4. The obtained specific power, specific energy and coulombic efficiency values of NiO electrode are 19.48xa0kW kg−u20091, 60.12 Whkg−u20091, and 92.31%, respectively. In the meantime it exhibited excellent cycle life time with 92.3% specific capacitance kept after 1000 cycles. These results imply that NiO electrode is promising candidate for upcoming thin film supercapacitors and other microelectronic constructions.

Synthesis and enhanced ethanol sensing performance of nanostructured Sr doped SnO2 thick film sensor

In the present paper we have synthesized pristine and Sr doped SnO2 in order to prepare a selective ethanol sensor with rapid response–recovery time and good repeatability. Pristine as well as Sr (2, 4 and 6xa0mol%) doped SnO2 nanostructured powder was synthesized by using a facile co-precipitation method. The samples were characterized by TG–DTA, XRD, HR-TEM, SAED, FEG-SEM, SEM–EDAX, XPS, UV–Vis and FTIR spectroscopy techniques. The gas response performance of sensor towards ethanol, acetone, liquid petroleum gas and ammonia has been carried out. The results demonstrate that Sr doping in SnO2 systematically decreases crystallite size, increases the porosity and hence enhances the gas response properties of pristine SnO2 viz. lower operating temperature, higher ethanol response and better selectivity towards ethanol. The response and recovery time for 4xa0mol% Sr doped SnO2 thick film sensor at the operating temperature of 300xa0°C were 2 and 7xa0s, respectively.

Synthesis, structural and optical properties of Fe-doped nanocrystalline SnO2

In the present study we have fabricated Fe doped SnO2 nanoparticles co-precipitation method. These samples were characterized by thermal gravimetric and differential thermal analysis, X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy (FE-SEM), energy dispersive studies by X-rays technique, transmission electron microscopy,selected area electron diffraction studies, Ultraviolet–Visible spectroscopy, fourier transform infrared (FTIR) spectroscopy, Raman and photoluminescence (PL) spectroscopicmeasurements. XRD analysis revealed the single phase rutile tetragonal structure of all samples. These results werefurther confirmed by Raman and FTIR studies. Crystallite size was observed to vary from 17 to 8xa0nm as the Fe content increased from 0 to 4xa0mol%, suggesting the prevention of crystal growth with Fe doping. It was evident from the absorption spectra that the absorbance increases with the dopant concentration. Optical band gap was estimated by using Tauc relation whichdecreases with the increase in Fe content confirmingthe size reduction as a result of Fe doping. Raman spectroscopic measurementsshowed thatthe broadening of intense peak observed at 630xa0cm−1 with Fe doping, indicating that the Fe ions are substituted at the Sn sites in SnO2 lattice. Room temperature PL spectra revealed that luminescent emission intensity increases with Fe concentration.

Structural, Optical and Ethanol Sensing Properties of Dy-Doped SnO 2 Nanoparticles

AbstractWe report a facile co-precipitation synthesis of dysprosium (Dy3+) doped tin oxide (SnO2) thick films and their use as gas sensors. The doping percentage (Dy3+) was varied from 1xa0mol.% to 4xa0mol.% with the step of 1xa0mol.%. As-produced material with varying doping levels were sintered in air; and by using a screen printing technique, their thick films were developed. Prior to sensing performance investigations, the films were examined for structural, morphological and compositional properties using x-ray diffraction, a field emission scanning electron microscope, a transmission electron microscope, selected area electron diffraction, energy dispersive analysis by x-rays, Fourier transform infrared spectroscopy and Raman spectroscopic techniques. The structural analyses revealed formation of single phase nanocrystalline material with tetragonal rutile structure of SnO2. The morphological analyses confirmed the nanocrystalline porous morphology of as-developed material. Elemental analysis defined the composition of material in accordance with the doping concentration. The produced sensor material exhibited good response towards different reducing gases (acetone, ethanol, LPG, and ammonia) at different operating temperatures. The present study confirms that the Dy3+ doping in SnO2 enhances the response towards ethanol with reduction in operating temperature. Particularly, 3xa0mol.% Dy3+ doped sensor exhibited the highest response (∼u200992%) at an operating temperature of 300°C with better selectivity, fast response (∼u200913xa0s) and recovery (∼u200922xa0s) towards ethanol.Graphical AbstractThe concise representation of conducted work: (a) EDAX, (b) ethanol sensing mechanism, (c) sensor response, and (d) SEM image of Dy: SnO2 nanoparticles.n

Enhanced NO2 response of hydrothermally grown Ti doped WO3 nanostructures

Titanium doped WO3 (Ti doped WO3) nanostructures were synthesized by hydrothermal synthesis by the controlled hydrolysis of Na2WO4 using oxalic acid and Titanium tetrachloride. Prepared samples were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), and transmission electron microscopy (TEM). As-synthesized pristine WO3 showed nanorods with diameters of about 10–15xa0nm and length about 1.2xa0µm and Ti doped WO3 composed of numerous small nanocrystals. Introduction of Ti doping by chemical synthesis process suppressed the growth of one-dimensional nanorods along their axis direction and shows agglomeration of particulate like morphology and no elongated structures. Ti doping not only lowered the optimal operating temperature of WO3 nanostructures sensors from 250 to 200xa0°C but also increased the maximum value of sensor response. Also the Ti-doped WO3 nanostructures exhibited rapid response characteristic to NO2 gas compared to pristine WO3.

Microwave synthesis and acetone sensing properties of WO3 hierarchical nanostructures

Citric acid mediated flower-like WO3 architectures were successfully synthesized via a facile microwave hydrothermal method. Potassium sulphate was used as a structure directing agent, which plays a significant role in governing morphology during synthesis. The morphology and structures were examined by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The results indicate that microflower-like morphology forms by assembly of polycrystalline orthorhombic WO3 nanorods. It is found that the sensor based on flower-like microstructure exhibits good sensitivity towards acetone with detection limit up to 1xa0ppm.

Organic acids assisted hydrothermal synthesis of WO 3 nanoplates and their gas sensing properties

Tungsten oxide is amongst the most widely used materials in electro-, photo-chromic applications. Recently tungsten oxide has been employed as sensing layer for detection of hazardous gases. In this work, we report synthesis of WO3 nanoparticles via a facile hydrothermal method using sodium tungstate and different organic acids (viz. citric acid, oxalic acid, malonic acid, and (L+) tartaric acid). We have investigated the effect/role of organic acid on the morphology and gas sensing properties. The X-ray diffraction (XRD) studies confirmed that citric acid and oxalic acid assisted routes give monoclinic structure (m-WO3) while malonic acid and (L+) tartaric acid give hexagonal structure (h-WO3). The nanoplate-like morphology was revealed by Scanning electron microscopy (SEM) analysis. The thick film of WO3 powder was deposited by using a screen printing technique. The gas response of thick films fired at 400°C/2h was studied. The change in the gas response of WO3 nanoplates for various concentrations and operating temperatures were studied for NOX, acetone, ethanol and ammonia vapors. In general, we observed response towards acetone, ethanol and ammonia vapors at higher operating temperature. However, the citric acid, oxalic acid and tartaric acid assisted WO3 exhibited good response for NOX at lower operating temperature (from 80°C-200°C). The gas response studies revealed that WO3 synthesized by citric acid assisted route exhibits highest sensitivity (S=77%) at 130°C towards NOX gas.

Structural and Bulk Magnetic Properties of Ni‐Co‐Zn Ferrites

Ni0.35−xCoxZn0.65fe2O4 (xu2009=u20090.00, 0.01, ‐‐‐‐0.10) ferrites were synthesized by coprecepitation technique, using oxalate precursors. The x‐ray diffraction studies have revealed a single spinel phase for all the compositions. Lattice parameter [a] increases with increasing Co2+ content. The magnitude of grain size (D) observed to be the same as reported by PJ. van der Zaag et al [1] for mono‐domains. The decrease in initial permeability is attributed to decrease in (i) grain size (D), (ii) decrease in saturation magnetization (Ms), and (iii) increase in magnetocrystalline anisotropy (K1). The variation in magnetocrystalline anisotropy is significant and becomes positive and large with the content of Co2+.