The Structure of Yttrium Cobaltate from Neutron Diffraction

Abstract

The crystal structure of YCoO3has been determined from Rietveld analysis of the powder neutron diffraction data at 17, 100, and 300 K. At each temperature, the structure is a distorted perovskite with orthorhombic symmetry, space groupPbnm(Z=4). The lattice parameters, at 300 K, are 5.1388(5)× 5.4191(5)×7.3658(7) Å. Structural analysis indicates that the formal valence of cobalt in YCoO3is +3. Analysis of the Co-O distances and the absence of magnetic structure indicates that the majority of the Co3+ions in YCoO3are in the low-spin (i.e.t62ge0g) state. The data also show that perhaps 10% of the Co3+ions at 300 K (but insignificant fractions at 100 and 17 K) are in the high-spin state. © 1997 Academic Press.