Cation modified A2(Ba, Sr, and Ca)ZnWO6 cubic double perovskites: A theoretical study

TL;DR

This theoretical study investigates how substituting different A-site cations in A2ZnWO6 double perovskites affects their structural, electronic, dielectric, and optical properties using DFT calculations.

Contribution

The paper provides a detailed theoretical analysis of the impact of A-site cation modification on the properties of A2ZnWO6 double perovskites, highlighting changes in band gap and charge localization.

Findings

All compounds are indirect wide band gap semiconductors.

Band gap decreases from Ba to Ca cation substitution.

Cation site modification significantly influences electronic and optical properties.

Abstract

The cubic double perovskites A2ZnWO6 (A = Ba, Sr and Ca) are studied to understand the effect of A cation site, using the density functional theory (DFT) based full potential augmented plane wave method (FP-LAPW) with GGA and mBJ exchange correlation potentials. The structural robustness and stability are investigated using the bond lengths and the total energy. The band structure and density of states suggest that all these cubic double perovskites are indirect wide band gap semiconductors. The band gap varies from 3.90 eV (2.97 eV) for Ba2ZnWO6 system to 3.40 eV (2.8 eV) for Ca2ZnWO6 system using mBJ (GGA) exchange correlation potentials. Our studies suggest that cation site modification has a strong effect on physical and electronic properties, in contrast to the structural robustness. The lattice parameter decreases from 8.19 Angstrom to 7.9 Angstrom from Ba to Ca at alkali cation site and the electronic band gap variation follows the common cation rule. The charge densities show enhanced localization of charges near the zinc and oxygen sites with increasing alkali cation atomic radii. In addition, we discuss the impact of A site cation modification on the dielectric and optical properties for A2ZnWO6 double perovskites.