Pressure-Induced Structural Phase Transition in CeNi: X-ray and Neutron Scattering Studies and First-Principles Calculations

TL;DR

This study combines experimental X-ray and neutron scattering with first-principles calculations to analyze the pressure-induced structural phase transition in CeNi, revealing a new Pnma phase and providing insights into its phase diagram and transition characteristics.

Contribution

It is the first to identify the Pnma structure in pressure-induced CeNi phases and to integrate experimental data with DFT calculations for comprehensive understanding.

Findings

CeNi undergoes a Cmcm to Pnma transition under pressure.

DFT calculations accurately reproduce transition pressure and volume collapse.

An approximate P-T phase diagram for CeNi is proposed.

Abstract

The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by X-ray and neutron powder diffraction techniques. For the first time it is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P < 8 GPa and T < 300 K. The observed Cmcm -> Pnma structural transition is analyzed using density functional theory (DFT) calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated with the phase transition.