Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
J Am Chem Soc. 2010 Jul 14;132(27):9438-43. doi: 10.1021/ja102987d.
The structural and electronic properties of BiCoO(3) under high pressure have been investigated. Synchrotron X-ray and neutron powder diffraction studies show that the structure changes from a polar PbTiO(3) type to a centrosymmetric GdFeO(3) type above 3 GPa with a large volume decrease of 13% at room temperature revealing a spin-state change. The first-order transition is accompanied by a drop of electrical resistivity. Structural results show that Co(3+) is present in the low spin state at high pressures, but X-ray emission spectra suggest that the intermediate spin state is present. The pressure-temperature phase diagram of BiCoO(3) has been constructed enabling the transition temperature at ambient pressure to be estimated as 800-900 K.
高压下 BiCoO(3) 的结构和电子性质已经过研究。同步加速器 X 射线和中子粉末衍射研究表明，在 3GPa 以上，结构从极性 PbTiO(3)类型转变为中心对称 GdFeO(3)类型，室温下体积减少 13%，表明自旋态发生变化。一级相变伴随着电阻率的下降。结构结果表明，Co(3+)在高压下处于低自旋态，但 X 射线发射光谱表明存在中间自旋态。构建了 BiCoO(3)的压温相图，使得可以估计常压下的转变温度为 800-900K。
