Xu Zheying, Thakur Pardeep K, Lee Tien-Lin, Regoutz Anna, Suard Emmanuelle, Puente-Orench Inés, Hayward Michael A
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, U.K.
Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K.
Inorg Chem. 2022 Oct 3;61(39):15686-15692. doi: 10.1021/acs.inorgchem.2c02747. Epub 2022 Sep 21.
Topochemical reduction of the cation-disordered perovskite oxides LaCoRhO and LaNiRhO with Zr yields the partially anion-vacancy ordered phases LaCoRhO and LaNiRhO, respectively. Neutron diffraction and Hard X-ray photoelectron spectroscopy (HAXPES) measurements reveal that the anion-deficient phases contain Co/Ni and a 1:1 mixture of Rh and Rh cations within a disordered array of apex-linked MO square-planar and MO square-based pyramidal coordination sites. Neutron diffraction data indicate that LaCoRhO adopts a complex antiferromagnetic ground state, which is the sum of a C-type ordering (mM) of the -components of the Co spins and a G-type ordering (mΓ) of the -components of the Co spins. On warming above 75 K, the magnitude of the mΓ component declines, attaining a zero value by 125 K, with the magnitude of the mM component remaining unchanged up to 175 K. This magnetic behavior is rationalized on the basis of the differing d-orbital fillings of the Co cations in MO square-planar and MO square-based pyramidal coordination sites. LaNiRhO shows no sign of long-range magnetic order at 2 K - behavior that can also be explained on the basis of the d-orbital occupation of the Ni centers.
用Zr对阳离子无序钙钛矿氧化物LaCoRhO和LaNiRhO进行拓扑化学还原，分别得到部分阴离子空位有序相LaCoRhO和LaNiRhO。中子衍射和硬X射线光电子能谱（HAXPES）测量表明，阴离子缺陷相在顶点相连的MO方形平面和MO方形基底金字塔形配位位点的无序阵列中包含Co/Ni以及Rh和Rh阳离子的1:1混合物。中子衍射数据表明，LaCoRhO采用复杂的反铁磁基态，它是Co自旋的 - 分量的C型有序（mM）和Co自旋的 - 分量的G型有序（mΓ）的总和。在加热到75 K以上时，mΓ分量的大小下降，到125 K时达到零值，而mM分量的大小在175 K之前保持不变。这种磁行为基于MO方形平面和MO方形基底金字塔形配位位点中Co阳离子不同的d轨道填充得以合理化。LaNiRhO在2 K时没有长程磁有序的迹象——这种行为也可以基于Ni中心的d轨道占据来解释。
