Pressure effects on the charge-ordering transition of BaYCo2O5.0

Abstract

Pressure effects on the charge-ordering (CO) transition have been investigated for an oxygen-deficient double-perovskite cobalt oxide, BaYCo 2 O 5.0 , through resistivity measurements using a piston-cylinder-type clamp cell. The charge-ordering temperature TCO rises (+19 K / G P a ) as pressure increases, making a sharp contrast with the pressure suppression of TCO seen for the isostructural BaSmFe 2 O 5.0 . We have further determined the atomic coordinates under elevated pressures, and ascribed this unexpected behavior of BaYCo 2 O 5.0 to the pressure enhancement of the orthorhombic distortion s (≡ a − b ) . © 2004 American Physical Society