Low Temperature Structural Phase Transition in the Perovskite Ba2CaMoO6

TL;DR

This study investigates a low-temperature structural phase transition in Ba2CaMoO6, revealing a change from cubic to tetragonal symmetry around 200 K through diffraction and calorimetry, enhancing understanding of perovskite structural behavior.

Contribution

It reports the first detailed structural and thermodynamic analysis of the phase transition in Ba2CaMoO6, highlighting its significance in perovskite research.

Findings

Structural transition from cubic to tetragonal at ~200 K

Confirmed by synchrotron and neutron diffraction

Thermodynamic evidence from calorimetry

Abstract

Ba2CaMoO6 was synthesized by solid state method. The crystal structure adopts cubic Fm-3m space group at room temperature with lattice parameters of 8.378231(5) {angstroms}. Upon cooling, Ba2CaMoO6 was determined to have a structural phase transition to tetragonal I4/m (a=5.905763(6) {angstroms} and c=8.38817(1) {angstroms}) around 200 K. The phase transition was probed structurally by synchrotron and neutron diffraction and thermodynamically by specific heat and differential scanning calorimetry measurement. This structural phase transition will deepens our understanding of the perovskite family especially the formation of perovskites that break corner sharing networks.