Structure–property relationships of YbFe2O4– and Yb2Fe3O7–type layered oxides: A bird's eye view

This work surveys the structural and physical properties of layered hexagonal (A3+M3+O3)(M2+O) and (A3+M3+O3)2(M2+O) phases where A3+ = In, Lu, Y, Yb, M3+ = Fe, Ga and M2+ = Cu, Mg, Zn. This family of compounds is of recent interest because of the trigonal bipyramid coordination that is rarely observed in transition metal oxides. The lattice parameters for a number of the (A3+M3+O3)(M2+O) and (A3+M3+O3)2(M2+O) compositions are provided herein, in addition to the bond lengths and atomic positions of selected compositions. The triangular geometry of the cations in the trigonal bipyramidal layers adds a component of frustration into the system, specifically with the magnetic properties. The work summarized in this review has used cation substitutions into the trigonal bipyramidal site of YbFe2O4-type compounds to further understand how the rare crystallographic coordination dictates the observed physical properties.