Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Inorg Chem. 2012 Aug 6;51(15):8502-8. doi: 10.1021/ic3010695. Epub 2012 Jul 26.
The crystallographic and physical properties of TbRuAsO and DyRuAsO at and below room temperature are reported, including full structure refinements from powder X-ray diffraction data and measured electrical and thermal transport properties, magnetic susceptibility, and heat capacity. Both compounds are isostructural to LaFeAsO (ZrCuSiAs-type, P4/nmm) at room temperature. However, DyRuAsO undergoes a symmetry-lowering crystallographic phase transition near 25 K, and adopts an orthorhombic structure (Pmmn) below this temperature. This structural distortion is unlike those observed in the analogous Fe compounds. Magnetic phase transitions are observed in both compounds which suggest antiferromagnetic ordering of lanthanide moments occurs near 7.0 K in TbRuAsO and 10.5 K in DyRuAsO. The nature of the structural distortion as well as thermal conductivity and heat capacity behaviors indicate strong coupling between the magnetism and the lattice. The behaviors of both materials show magnetic ordering of small moments on Ru may occur at low temperatures.
报道了 TbRuAsO 和 DyRuAsO 在室温及以下温度的晶体学和物理性质，包括从粉末 X 射线衍射数据进行的全结构精修以及测量的电输运和热输运性质、磁化率和热容。这两种化合物在室温下与 LaFeAsO（ZrCuSiAs 型，P4/nmm）具有相同的结构。然而，DyRuAsO 在 25 K 附近经历了一个降低对称性的晶体相转变，并在低于此温度下采用正交结构（Pmmn）。这种结构变形与在类似的 Fe 化合物中观察到的不同。在这两种化合物中都观察到了磁相变，这表明 TbRuAsO 中镧系元素磁矩的反铁磁有序发生在 7.0 K 附近，DyRuAsO 中发生在 10.5 K。结构变形以及热导率和热容行为的性质表明，磁体和晶格之间存在强烈的耦合。这两种材料的行为都表明，Ru 上的小磁矩可能在低温下发生磁有序。
