High‐pressure neutron diffraction measurements of polycrystalline LaFeO3 are collected up to 5.5 and 6.4 GPa at 290 and 110 K, respectively. The bulk moduli are determined as B0(290 K) = 170(3) GPa and B0(110 K) = 175(1) GPa. The unit cell is found to compress anisotropically at both temperatures with the a‐axis compressing preferentially. A crossover in lattice parameters is observed, from a > c to c > a, at 2 GPa at 290 K and at 1.7 GPa at 110 K. The magnetic moment remains unchanged over the pressure range investigated, with a value of 4.4 μB and 4 μB at 110 and 290 K, respectively. Analysis of the octahedral tilting angles and the spontaneous lattice strains shows an increased orthorhombic distortion with pressure, but shows no trend toward a change in symmetry. High‐pressure Raman spectroscopy measurements at room temperature are in agreement with the diffraction data.

The authors report a high-pressure variable-temperature neutron diffraction study of LaCoO 3 , from ambient to 6 GPa at 120, 290, and 480 K. The authors see no evidence for previously-reported discontinuities in the Co─O and La─O distances in the pressure and temperature ranges studied. Such discontinuities have previously been attributed to the well-documented spin-state transition of the Co 3þ cation (from t 5 2g e 1 g , S ¼ 1 !t 6 2g e 0 g , S ¼ 0), the authors conclude that manifestations of the electronic configuration of LaCoO 3 are not evident in the crystallographic structure upon pressurization. The authors also report bulk moduli for each of these temperatures as 134 (2), 135(1), and 111(1) GPa, respectively, as fitted to a second-order Birch-Murnaghan equation of state.