Structural and electronic properties of rare earth chromites: A computational and experimental study

TL;DR

This study combines experimental synthesis and characterization with first-principles calculations to analyze the structural and electronic properties of rare-earth chromites RCrO3, revealing how ionic radii influence structural parameters but not band gaps.

Contribution

It provides a comprehensive analysis of RCrO3 compounds using both experimental techniques and advanced DFT calculations, highlighting the accuracy of SCAN+U in predicting properties.

Findings

Lattice parameters depend on the ionic radii of R

Band gaps are independent of R ionic radii

SCAN+U yields more accurate structural and electronic predictions

Abstract

In this work, the structural, optical, and electronic properties of rare-earth perovskites of the general formula RCrO3, where R represents the rare-earth Gd, Tb, Dy, Ho, Er, and Tm, have been studied in detail. These compounds were synthesized through a facile citrate route. X-ray diffraction, Raman spectroscopy, and UV-Vis spectroscopy were used to reveal the structural evolutions in RCrO3. The lattice parameter, Cr3+-O2--Cr3+ bond angle, and CrO6 octahedral distortions were found to strongly depend on the ionic radii of the rare-earth element. First-principles calculations based on density-functional theory within the generalized gradient approximation (GGA) of Perdew- Burke- Ernzerhof (PBE) and strongly constrained-and-appropriately normed (SCAN) meta-GGA were also employed to calculate the structural and electronic properties of RCrO3. The ground-state energy, lattice constants, electronic structure, and density of states (DOS) of RCrO3 were calculated. These provide some insights into the electronic characteristics of the series of RCrO3 compounds. The calculated values of lattice parameters and band gaps with Hubbard U correction (SCAN+U) agree well with values measured experimentally and show more accuracy in predicting the ground-state crystal structure and band structure compared to PBE+U approximation. The band gap of RCrO3 is found to be independent of the ionic radii of the element R from both experiments and calculations