RESUMO
The nanocrystalline strontium cobalt molybdate composites of Sr1-xCoxMoO4 (x = 0, 0.3, 0.5, 0.7, 1) were prepared by mixing various mole ratios (SrM-1, SrCM-2, SrCM-3, SrCM-4 and CoM-5) and investigated for their humidity sensing properties. The composites were characterized by thermal analysis (TG/DTA), X-ray powder diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Fourier Transform Raman (FT-Raman) spectroscopy, Scanning Electron Microscopy (SEM/EDAX), Transmission Electron Microscopy (TEM) and UV-Visible absorption spectroscopy. The composites were subjected to dc electrical conductivity based humidity sensing studies at room temperature. The resistance measurements as a function of relative humidity (RH) in the range of 5-98% were carried out and the sensitivity factor (Sf) were calculated. The SrM-1 is found to possess with the highest Sf of 33014 ± 660 and CoM-5 is found to possess a low Sf of 868 ± 43. The SrCM-2, SrCM-3 and SrCM-4 possessed the sensitivity factors (Sf) of 915 ± 45, 3713 ± 185 and 3390 ± 102 respectively.
RESUMO
Ni2+ -doped LaVO3 perovskites nanostructures were successfully prepared by a simple coprecipitation method. Powder X-ray diffraction (XRD) pattern confirms that all compositions crystallize with orthorhombic LaVO3 perovskites structure. The lattice parameter decreases with increase in Ni2+ content resulting in the reduction of lattice strain in LaVO3. High resolution scanning electron microscope (HR-SEM) images revealed that the as-prepared samples are crystalline with particle size distribution in 142-250 nm range. The BET studies revealed the surface area of the required samples. The samples were subjected to humidity sensing studies by solid-state electrical conductance studies. The studies revealed that La0.4Ni0.6VO3 is a good candidate for humidity sensors with a higher sensitivity factor (Sf) of 15623.02. The higher Sf of La0.4Ni0.6VO3 is due to the larger surface area of the sample.