Studies on Local Structural Inhomogeneity and Origin of Ferroelectricity in Yttrium chromite Ceramics

Abstract

YCrO3 (YCO) is known to be a multiferroic with orthorhombic, Pnma, structure with center of inversion. However, the local structural inhomogeneity in this compound is believed to give rise to ferroelectric behavior. In this study we explore high temperature Raman investigations of YCO and observed that one of its Raman mode B3g (3) (CrO6 Octahedral tilt mode) softens around the structural phase transition which could be the origin of ferroelectric nature in YCO. In addition, we substitute bismuth (Bi) in YCO to understand the structural distortions that lead to local structural inhomogeneity. Besides B3g (3) mode softening with composition and high temperature studies in Y1-xBixCrO3 the study reveals the structural distortions and the structural tunability Bi offers in such systems.

AC - conductivity studies on Y1-xBixCrO3 solid solution

“…Diffraction studies on Y 1-x Bi x CrO 3 (x=0 to 0.15) compounds are well refined with the orthorhombic Pnma structure without any impurity at room temperature, reported elsewhere 8 . Increase of lattice parameters, volume expansion and increase of Cr-O2-Cr bond angles are consistent with Bi +3 (r=1.11Å) in Y +3 -site (r =1.02 Å).…”

A comprehensive review on the ferroelectric orthochromates: Synthesis, property, and application

“…The local structural inhomogeneity in YCrO 3 was studied by Mannepalli et al [244]. One of the Raman mode B 3g (3) was observed softening and disappearing at temperatures higher than the dielectric transition, which was attributed to the CrO 6 octahedral tilting mode [244,245], indicating that the local structural inhomogeneity may be the reason for the ferroelectricity of YCrO 3 . By the way, the substitution of Bi for Y ions in YCrO 3 also resulted in the local structural inhomogeneity.…”

“…(7) Y 1−x Bi x CrO 3 . Mannepalli and Ramadurai prepared Y 1−x Bi x CrO 3 (x = 0, 0.05, 0.1, and 0.15) samples by the sol-gel route in order to study the local-structure inhomogeneity [244]. The study indicated that the unit-cell volume expansion by substituting Bi 3+ in Y-sites could soften the B 3g (3) Raman mode associated with the tilting of CrO 6 octahedra around the structural phase transition.…”

“…The study indicated that the unit-cell volume expansion by substituting Bi 3+ in Y-sites could soften the B 3g (3) Raman mode associated with the tilting of CrO 6 octahedra around the structural phase transition. This was believed to induce the ferroelectric behavior in YCrO 3 [244]. The conductivity was measured using dielectric spectroscopy.…”