We present an in-depth study on the structure and magnetic properties of a novel layered oxide, Ca₂Fe_0.875Cr_0.125GaO₅. Structural studies from laboratory X-ray diffraction, synchrotron powder X-ray diffraction and neutron powder diffraction reveal that the compound crystallizes in an orthorhombic Brownmillerite phase with Pnma space group having Fe/Cr – octahedral layers and Ga – tetrahedral layers with around 9.0% of Fe occupying tetrahedral sites. The temperature evolution of Neutron powder diffraction confirms the absence of any structural changes in the range 300–6 K. Magnetic characterizations show antiferromagnetic ordering at room temperature and the co-existence of antiferromagnetic and ferromagnetic phases at low temperature. The magnetic structure derived from neutron powder diffraction is a G-type antiferromagnetic. The ordered magnetic moments at 6 K on the octahedral and tetrahedral sites are 3.15 (2) µ_B/cation and 0.93 (4) µ_B/cation, respectively oriented in the ac-plane.

我们对新型层状氧化物Ca ₂ Fe _0.875 Cr _0.125 GaO ₅的结构和磁性能进行了深入研究。通过实验室X射线衍射，同步加速器粉末X射线衍射和中子粉末衍射的结构研究表明，该化合物在Pnma空间群的正交晶Brownmillerite相中结晶。具有Fe / Cr –八面体层和Ga –四面体层，其中约9.0％的Fe占据四面体位置。中子粉末衍射的温度演变证实在300-6 K范围内不存在任何结构变化。磁性表征显示，室温下反铁磁有序，而低温下反铁磁相和铁磁相并存。来自中子粉末衍射的磁性结构是G型反铁磁性。八面体和四面体位点上6 K的有序磁矩分别为3.15（2）µ_B/阳离子和0.93（4）µ_B/阳离子，分别定向于ac平面。