科研之友
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摘要
The crystal structure and magnetic structure of the chromate series ACrO(3) (A = Ca, Sr, Pb) where Cr exhibits the unusual Cr4+ oxidation state have been studied by comprehensive diffraction experiments. In addition we present a detailed analysis of the infrared optical properties of polycrystalline CaCrO3 which is found to be metallic along all crystallographic directions. CaCrO3 forms the rare case of a three-dimensional antiferromagnetic and metallic transition-metal oxide in which the occurrence of magnetic ordering is closely coupled to a flattening of the lattice. The same C-type magnetic order is also found in the Sr material and again is coupled to a structural distortion associated with lattice flattening. However, in SrCrO3 only a part of the sample transforms into the antiferromagnetic distorted phase. In contrast to CaCrO3 and SrCrO3, PbCrO3 clearly is insulating with a significantly larger unit-cell volume and exhibits G-type magnetic order.
- 出版日期2011-9-9
- 单位中国地震局
