Spin-state transitions in PrCoO ₃ studied with neutron powder diffraction

The crystal structure of PrCoO ₃ has been studied with high-resolution neutron powder diffraction and pair-distribution-function analysis in the temperature range from 12-600 K. The compound has the orthorhombic (Pbnm) perovskite structure over the entire temperature range. The temperature dependence of the average Co-O bond length shows clear anomalies near 60 K and 200 K where anomalous temperature dependencies of thermal conductivity and magnetic susceptibility have been reported. The data show a constant intermediate-spin-state fraction within 60<T<200 K and excitation of high-spin-state Co(III) above 200 K.