Structural phase transition of ternary high-k dielectric SmGdO3: Evidence from ADXRD and Raman Spectroscopic Studies

TL;DR

This study investigates the pressure-induced phase transition in SmGdO3 using ADXRD and Raman spectroscopy, revealing a reversible transition from monoclinic to hexagonal structure around 8.9 GPa and providing detailed mechanical and vibrational properties.

Contribution

First comprehensive pressure-dependent structural and vibrational analysis of SmGdO3, identifying phase transition and calculating related physical parameters.

Findings

Reversible phase transition at ~8.9 GPa from monoclinic to hexagonal

Bulk moduli determined for both phases: 132 GPa and 177 GPa

Pressure-dependent Raman modes and Gruneisen parameters calculated

Abstract

High-pressure synchrotron based angle dispersive x-ray diffraction (ADXRD) studies were carried out on SmGdO3 (SGO) up to 25.7GPa at room temperature. ADXRD results indicated a reversible pressure-induced phase transition from ambient monoclinic to hexagonal phase at about 8.9 GPa. The observed pressure-volume data were fitted into the third order Birch-Murnaghan equation of state yielding zero pressure bulk moduli B0 = 132(22) and 177(22) GPa for monoclinic and hexagonal phases, respectively. Pressure dependent micro-Raman spectroscopy further confirmed the phase transition. The mode Gruneisen parameters and pressure coefficients for different Raman modes corresponding to each individual phase of SGO were calculated.