RCrO 3 ( R = La, Nd, Eu, Gd, Dy, and Y)]]>

摘要

We present here, a systematic investigation on orthorhombic perovskite type rare earth chromates;RCrO3(R=La, Nd, Eu, Gd, Dy, and Y) powder samples via X-ray diffraction, Raman and UV–Visible spectroscopy. The Rietveld fitted X-ray diffraction patterns confirm the formation of single phase orthorhombic structure withPnmaspace group for all the samples. A comprehensive analysis of Rietveld fitted data has been performed to further see the effect of change in the size of rare earth (R3+) ions on bond length and structural distortions. It has been noticed that bond length (RO) decreases with decrease in radius of R-site ions, consequently an increase in the distortion or the octahedral tilting. Raman spectroscopy results reveal the blue shift in these samples with decrease in the size of the rare-earth ion, owing to change in their bond lengths. Optical properties have been also noticed via UV–visible absorption spectroscopy technique. These results indicate that theRCrO3materials are transparent in visible range with band gap varying from 2.19 to 3.20?eV.