Application of Principal Component Analysis to the Conductometric Cr1-xFexNbO4 (x=0, 0.5, 1.0) Thick Films Gas Sensors

The gas sensing characteristics of Cr1-xFexNbO4 (x = 0.0, 0.5, 1.0) towards different organic analytes and hydrogen were investigated at different operating temperatures. The slope of the retrace transient, a representative feature for desorption kinetics was considered for data exploration. 11 sensors with 12 samples were tested and the data obtained was processed using principal component analysis (PCA). The scores plot and loadings plot showed the possible differentiation of the cross sensitive analytes and redundancy of the sensor behaviour towards these analytes respectively

Sea Breeze Detection with Acoustic Radar

176-181A preliminary study on sea breeze fronts has been made at Visakhapatnam using a monostatic acoustic radar situated in the University campus, very near to the sea shore. During the summer of 1980 sea breeze was almost a daily phenomenon at Visakhapatnam, and was usually seen as a well marked distinct change in the character of the acoustic radar records. The increased thermal turbulence associated with the transfer of heat from the surface into the layer of marine air produced enhanced sound scattering up to the height of 150 m. The sea breeze often created an elevated layer usually in the height range 200-500 m. Acoustic backscatter records obtained in May 1980, when the sea breeze was strongest, are presented and discussed in the light of the prevailing weather conditions and previous experimental studies reported from this station

Conductometric Sensing of H-2 by Chromium Niobate

Investigations on chromium niobate (CrNbO4) have shown that the material responds to a wide hydrogen concentration range of 0.01%-0.40% at 613 K. The conductivity of CrNbO4 is independent of oxygen partial pressure and offers to be a promising candidate for monitoring H-2 in radioactive spent fuel storage facilities. Reduction of metal ions to lower valence states during hydrogen sensing was evidenced by X-ray photoelectron spectroscopic studies

Studies on physicochemical properties of pure and iron substituted chromium niobates, Cr1-xFexNbO4 (x=0, 0.2, 0.4, 0.6)

Pristine and iron substituted chromium niobates (Cr1-xFexNbO4 with x = 0, 0.2, 0.4 and 0.6) are prepared by solid-state synthesis and phase characterised by X-ray diffraction. Microstructure is determined using scanning electron microscope and micro-chemical analysis is performed by energy dispersive X-ray analysis (EDX). The current-voltage characteristics are studied in the temperature range of 423-723 K. The electrical conductivity of sintered pellets is measured by impedance spectroscopy. Temperature dependent magnetization studies are performed using vibrating sample magnetometer (VSM) and room temperature Bohr magneton number is calculated from the magnetic susceptibility data. The conductivity is passed through a minimum at x = 0.2 in Cr1-xFexNbO4 for x = 0-0.6. X-ray photoelectron spectroscopic studies revealed the surface non-stoichiometry in these compositions. (C) 2016 Elsevier B.V. All rights reserved