Crystal structure and ferrimagnetism of AgCo3Cr(MoO4)5 with mixed occupation of the transition metal sites†

Abstract

We prepared a new compound, AgCo₃Cr(MoO₄)₅, and characterized its crystal structure and physical properties. It crystallizes in the triclinic space group P with mixed occupation of the transition-metal sites M = (Co and Cr). The Ag site is split into three close positions. The magnetic subsystem of the title compound consists of M₂O₁₀ dimers and M₃O₁₄ trimers, made up of edge-sharing MO₆ octahedra. These units are interconnected by MoO₄ tetrahedra. Both ac and dc magnetic susceptibility, as well as specific heat and dielectric permittivity, evidence a ferrimagnetic behavior below T_ferri = 5.5 K. To investigate the properties of this nanostructured system, we evaluated spin exchanges for the four most probable magnetic ion arrangements. We found that considering the local structure is essential for understanding the behavior of a magnet with mixed occupation of the transition metal sites.