DOI: 10.1098/rsta.2022.0332 ISSN:

A structural study of PrCrO 3 under extreme conditions: a comparison with the effects of doping

C. L. Bull, N. P. Funnell, C. J. Ridley
  • General Physics and Astronomy
  • General Engineering
  • General Mathematics

The nuclear and magnetic structure of PrCrO 3 has been investigated using neutron and X-ray powder diffraction as a function of pressure and temperature. The orthorhombic symmetry (space group P b n m ) remains stable up to the highest temperature (1500 K) and pressure (approx. 6 GPa ) considered. There is a crossover in the magnitude of the a- and b -lattice parameters at approximately 1135 K, caused by competing effects of octahedral tilting and distortion. The material is antiferromagnetic ( T N 240  K) with P b n m symmetry, with a maximum moment of 2.34 ( 2 ) μ b on the Cr 3 + sites aligned along the direction of the a -axis. The application of pressure shows an abnormal softening in the unit-cell volume, which is suggestive of a continuous approach to a second-order phase transition. Raman spectroscopy measurements at ambient temperature were collected as a function of pressure up to approximately 12  GPa, with discontinuous mode behaviour further suggesting the existence of a transition above 7 GPa. The measured structural changes in PrCrO 3 are compared extensively in the wider context of other lanthanide orthochromites, and the comparative effects of A - and B -site substitution on the polyhedral tilts and distortion are discussed.

This article is part of the theme issue ‘Exploring the length scales, timescales and chemistry of challenging materials (Part 1)’.

More from our Archive