Tuning the Physical Properties of Fe doped YCrO3

Abstract

In this thesis work, we explored the tuning of the physical properties of Fe-doped newlineYCrO3 perovskite materials. A series of YCr1-xFexO3 (0 and#8804; x and#8804; 1) perovskite materials were newlinesynthesized using the solid-state reaction method. The crystallographic properties of the newlinesamples were analyzed using powder X-ray diffraction (PXRD), confirming an newlineorthorhombic structure for all compositions. Rietveld refinement of the PXRD data newlineconfirmed the lattice parameters (a, b, and c) and unit cell volume increased with newlineincreasing Fe substitution, suggesting that the lattice expansion arises due to the higher newlineionic radii substitution at the Cr-site. Based on these PXRD results, we found that the newlineYCr0.6Fe0.4O3 sample is more stable than the other prepared samples. Raman newlinespectroscopy revealed a red shift in characteristic modes with increasing Fe content, newlineattributed to lattice distortions induced by the larger ionic radius of Fe3+. FT-IR newlinespectroscopy further confirmed the presence of metal-oxygen vibrations, with shifts in newlinethe Cr/Fe-O and Y-O stretching modes. newlineThe optical band gap exhibited a non-monotonic trend, initially decreasing with Fe newlinesubstitution up to 50% before increasing at higher Fe concentrations. Dielectric newlinespectroscopy measurements indicated that YCr0.6Fe0.4O3 possessed the highest dielectric newlineconstant and the lowest tangent loss at low frequencies. AC conductivity decreased with newlineincreasing Fe content, while room-temperature P-E loops suggested weak ferroelectric newlinebehaviour. newlineWe also studied the Sr and Fe co-doped Y0.5Sr0.5Cr1-xFexO3 (x = 0 and 0.25) newlineperovskite samples synthesized using the solid-state reaction method. XRD analysis with newlineRietveld refinement confirmed an orthorhombic structure. Raman spectroscopy revealed newlinea red shift in vibrational peaks, consistent with Fe incorporation. The optical band gap of newlineY0.5Sr0.5CrO3 decreased from 3.07 eV to 2.24 eV upon Fe substitution, indicating newlinesignificant tuning of optical properties. newlineThese findings illustrate that Fe substitution, and co-substitution with Sr, can newlinesignificantly t