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

Abstract

Abstract The structural and physical properties of some chromites–manganites solid solutions (RE,Ca)Cr 0.5 Mn 0.5 O 3 , 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 YbCr 0.5 Mn 0.5 O 3 in which traces of hexagonal YbMnO 3 remain through all the synthesis and sintering processes. Incorporation of Mn 3+ cations does not alter the perovskite O-type structure of the chromites. Ca-containing solid solutions maintain the O-type structure. Magnetic measurements indicate an increase of the ferromagnetic behavior when Ca 2+ is incorporated into the lattice, with an expected transformation of Mn 3+ into Mn 4+ , and its associated ferromagnetic exchange interactions. Competition between ferromagnetic Mn 3+ –Mn 4+ , Mn 3+ –Cr 3+ and antiferromagnetic Cr 3+ –Mn 4+ , Yb–TM interactions (TM: transition metal) leads to complex magnetic ordering in the ytterbium chromites, although double exchange Mn 3+ –Mn 4+ interactions predominate and suppress the spin reversal expected for the pure YbCrO 3 material.