Jahn-Teller effect in low-spin Ni³⁺ in the LaAlO₃ ceramic

Abstract

This paper reports on an EPR study of LaAl_1−x Ni_xO₃ solid solutions with x≤0.12 made in the 4.2-to 300-K temperature range. In the X range, the broadening of the single EPR line with g _eff=2.148 was observed at temperatures below ∼40 K. In the Q range, a slightly anisotropic EPR line with g ^′_⊥ =2.145±0.002 and g ^′_‖ =2.154±0.002 transforms to a rhombic-symmetry spectrum with g ₁=2.183±0.002, g ₂=2.143±0.002, and g ₃=2.118±0.002. It is shown that the observed low-temperature effects are due to the lowered symmetry of the complex under the combined action of the tetragonal Jahn-Teller distortions and of the trigonal component of the crystal field.