Isostructural phase transition in Tb2Ti2O7 under pressure and temperature: Insights from synchrotron X-ray diffraction

TL;DR

This study uses synchrotron X-ray diffraction to investigate how Tb2Ti2O7's structure changes under pressure and temperature, revealing an isostructural phase transition beyond 10 GPa that affects its lattice and mechanical properties.

Contribution

It provides the first comprehensive analysis of the pressure-induced isostructural phase transition in Tb2Ti2O7 using high-brilliance synchrotron X-ray diffraction.

Findings

Confirmed isostructural phase transition beyond 10 GPa

Transition involves atomic rearrangement with cubic symmetry preserved

Transition is nearly temperature-independent

Abstract

Tb2Ti2O7, a pyrochlore system, has garnered significant interest due to its intriguing structural and physical properties and their dependence on external physical parameters. In this study, utilizing high-brilliance synchrotron X-ray diffraction, we conducted a comprehensive investigation of structural evolution of Tb2Ti2O7 under external pressure and temperature. We have conclusively confirmed the occurrence of an isostructural phase transition beyond the pressure of 10 GPa. The transition exhibits a distinct signature in the variation of lattice parameters under pressure and leads to changes in mechanical properties. The underlying physics driving this transition can be understood in terms of localized rearrangement of atoms while retaining the overall cubic symmetry of the crystal. Notably, the observed transition remains almost independent of temperature. Our findings provide insights into the distinctive behaviour of the isostructural phase transition in Tb2Ti2O7.