Phonon Raman scattering of RCrO3 perovskites (R = Y, La, Pr, Sm, Gd, Dy, Ho, Yb, Lu)

TL;DR

This study systematically investigates the Raman spectra of RCrO3 perovskites with nine different rare earth elements, providing reference data and correlating phonon modes with structural distortions, especially octahedral rotations.

Contribution

It offers comprehensive Raman spectra and phonon mode assignments for RCrO3 series, linking vibrational modes to structural distortions and octahedral tilt angles.

Findings

Two Ag phonon modes identified as octahedra rotation soft modes.

Phonon mode positions scale linearly with octahedral tilt angles.

Provides reference data for structural analysis of RCrO3 series.

Abstract

We report a systematic investigation of orthorhombic perovskite-type RCrO3 powder samples by Raman scattering for nine different rare earth R3+ cations (R = Y, La, Pr, Sm, Gd, Dy, Ho, Yb, Lu). The room-temperature Raman spectra and the associated phonon mode assignment provide reference data for structural investigation of the whole series of RCrO3 orthochromites and phonon ab-initio calculations. The assignment of the chromite spectra and comparison with Raman data on other orthorhombic perovskites allows correlating the phonon modes with the structural distortions in the RCrO3 series. In particular, two Ag modes are identified as octahedra rotation soft modes as their positions scale linearly with the octahedra tilt angle of the CrO6 octahedra.