Structural and magnetic properties of the solid solution ([formula omitted]) YMn1−x(Cu3/4Mo1/4)xO3

Abstract

Recently, the ferroelectromagnet YMnO3 has been the focus of interest because it exhibits both antiferromagnetism (Néel temperature ∼80 K) and ferroelectricity (Curie temperature ∼914 K). There have been no reports of complete YMn1−xMxO3 solid solutions in which substitution of the foreign M cation preserves the hexagonal P63cm structure. In contrast there exist several homeotypic phases with the general formula, Ln1+nCunMO3+3n (n=1 (M=Ti), 2 (M=V) and 3 (M=Mo); Ln: lanthanide). Several YMn1−x(Cu3/4Mo1/4)xO3 compounds have been synthesized. The solid solution, from YMnO3 (x=0) to YCu3/4Mo1/4O3 (x=1) has been characterized by X-ray diffraction and transmission electron microscopy study. For 0<x<0.9, the compounds are found to crystallize in the non-centrosymmetric structure, space group P63cm, of YMnO3. The Mn-free end member, x=1, crystallizes in a complex multiple cell, the superstructure being associated to Cu3+/Mo6+ cationic ordering. Dilution of the Mn3+ magnetic array by the paramagnetic (Cu2+) and diamagnetic (Mo6+) cations is found to decrease the antiferromagnetic ordering temperature and it becomes undetectable for x⩾0.5 compositions.