Structural, magnetic, dielectric and mechanical properties of (Ba,Sr)MnO$_3$ ceramics

TL;DR

This study investigates the structural, magnetic, dielectric, and mechanical properties of (Ba,Sr)MnO₃ ceramics, revealing phase transitions, magnetic ordering, and insights from ab initio simulations, contributing to understanding their multifunctional behavior.

Contribution

It provides comprehensive experimental and theoretical analysis of (Ba,Sr)MnO₃ ceramics, including phase transition details and ab initio energy contributions, which are novel insights in this material system.

Findings

Detected anomalies in lattice parameters of SMO at 600-800 K.

Observed Néel phase transition at 250 K in BSMO.

Ab initio simulations show 30% exchange correlation energy contribution.

Abstract

Ceramic samples, produced by conventional sintering method in ambient air, 6H-SrMnO$_3$(6H-SMO), 15R-BaMnO$_3$(15R-BMO), 4H-Ba$_{0.5}$Sr$_{0.5}$MnO$_3$(4H-BSMO) were studied. In the XRD measurements for SMO the new anomalies of the lattice parameters at 600-800 K range and the increasing of thermal expansion coefficients with a clear maximum in a vicinity at 670 K were detected. The N$\acute{e}$el phase transition for BSMO was observed at $T_N$=250 K in magnetic measurements and its trace was detected in dielectric, FTIR, DSC, and DMA experiments. The enthalpy and entropy changes of the phase transition for BSMO at $T_N$ were determined as 17.5 J/mol and 70 mJ/K mol, respectively. The activation energy values and relaxation times characteristic for relaxation processes were determined from the Arrhenius law. Results of ab initio simulations showed that the contribution of the exchange correlation energy to the total energy is about 30%.