Anuradha Yadav

EXPERIMENTAL INVESTIGATIONS ON NANOSIZED FERRIC OXIDE AND ITS LPG SENSING

Nanosized particles of α-Fe2O3 in the range of 17–64 nm were synthesized via hydroxide precipitation. The synthesized powder was investigated by XRD employing CuKα radiation and 2θ geometry. SEM images show the nanosheet like morphology. The pellet of this sensing material was made by hydraulic press under a uniaxial pressure of 616 MPa. The LPG sensing properties of α-Fe2O3 were investigated at room temperature for different exposure times of LPG. A maximum value of sensitivity and sensor response were found 3 and 213%, respectively for an exposure time of 300 s. Electrical properties of α-Fe2O3 in air were also investigated by measuring temperature–resistance (R–T) characteristics and plotting them as Arrhenius plot. Activation energy was calculated by thermal resistance method and found to have a value 1.07 eV.

Effect of Nanostructured Zinc Oxide Additives on the Humidity and Temperature Sensing Properties of Cuprous Oxide

Present paper reports the effect of ZnO additives on humidity and temperature sensing properties of cuprous oxide. The cuprous oxide powder was mixed with 10% and 25% ZnO by weight and these samples were pelletized by using hydraulic pressing machine. The sensing materials were also investigated by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). SEM images show morphology and porosity of material. The average particles size of cuprous oxide was found to be 1.2 micron. The sheet like structures of ZnO is evident in micrographs. From XRD all peaks are well identified and crystallite size for defferent peaks has also been calculated. The pellets of sensing materials were subjected to annealing at temperatures 200, 400 and 600 degrees C respectively and were exposed to humidity and temperature variations. Electrical resistances of pellets were found to vary with humidity and temperature and were recorded. The sensitivity of sensors at various temperature and humidity levels was calculated.

Synthesis and Characterization of ZnO/ZnNb2O6 Nanocomposite and Its Application as Humidity and LPG Sensor

ABSTRACT The present article reports the synthesis and characterization of ZnO/ZnNb2O6 nanocomposite and its humidity and liquefied petroleum gas (LPG) sensing behavior at room temperature. Pellets from the powder of synthesized material were calcined at 150, 300, 450, and 550°C for 3 h and tested for their humidity and LPG sensing ability separately. Each heat-treated pellet was exposed to humidity under controlled conditions, and variations in resistance with variations in humidity were measured. Similarly, heat treated pellets were exposed to LPG and variations in resistance were recorded. Electrical sensitivities of sensing material at different temperatures were also evaluated. After chemical mixing of niobium oxide with zinc oxide, the average sensitivity of a sensor increased from 8 to 19 MΩ/% relative humidity (RH) over the range from 10 to 95% RH at room temperature and in the case of LPG sensing, the maximum sensitivity was 12.

A mechanochemical synthesis of nanostructured zinc oxide via acetate route for LPG sensing

This article reports the liquefied petroleum gas (LPG) sensing of nanostructured zinc oxide (ZnO) synthesised via zinc acetate [Zn(CH3COO)2·2H2O] as precursor. The structural and morphological characterisations of the material were analysed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Structural analysis showed that material was highly crystalline having minimum crystallite size 15 nm. Surface morphological studies show nanospheres of ZnO throughout the surface, however not distributed uniformly. Optical characterisation of the sensing material was carried out by UV-Visible spectroscopy and FTIR spectroscopy. By Tauc plot, the estimated value of band gap of film was found 3.45 eV. The LPG-sensing properties of the ZnO pellet were investigated at room temperature for different vol.% of LPG. The variations in electrical resistance of the sensing pellet were measured with the exposure of LPG as a function of time. The maximum values of average sensitivity and sensor response factors were found ∼5 and 396, respectively, for 5 vol.% of LPG. The activation energy calculated from Arrhenius plot was found 0.61 eV. The response and recovery time of sensing pellet were found ∼90 and 110 s, respectively. These experimental results show that nanostructured ZnO is a promising material as LPG sensor.