Crystalline and magnetic properties of Er and Yb chromites modified by Mn and Ca cations

The structural and physical properties of some chromites–manganites solid solutions (RE,Ca)Cr0.5Mn0.5O3, RE = Er, Yb, have been studied by X-ray diffraction and magnetic measurements. Powders were prepared by solid state reaction between the component oxides. Complete solid solutions were obtained, except for YbCr0.5Mn0.5O3 in which traces of hexagonal YbMnO3 remain through all the synthesis and sintering processes. Incorporation of Mn3+ cations does not alter the perovskite O-type structure of the chromites. Ca-containing solid solutions maintain the O-type structure. ic measurements indicate an increase of the ferromagnetic behavior when Ca2+ is incorporated into the lattice, with an expected transformation of Mn3+ into Mn4+, and its associated ferromagnetic exchange interactions. Competition between ferromagnetic Mn3+–Mn4+, Mn3+–Cr3+ and antiferromagnetic Cr3+–Mn4+, Yb–TM interactions (TM: transition metal) leads to complex magnetic ordering in the ytterbium chromites, although double exchange Mn3+–Mn4+ interactions predominate and suppress the spin reversal expected for the pure YbCrO3 material.