Structural and magnetic properties of the solid solution (0 ≤ x ≤ 1) YMn1-x(Cu3/4Mo1/4)xO3

Recently, the ferroelectromagnet YMnO3 has been the focus of interest because it exhibits both antiferromagnetism (Neel temperature similar to 80 K) and ferroelectricity (Curie temperature similar to 914 K). There have been no reports of complete YMn1-xMxO3 solid solutions in which substitution of the foreign M cation preserves the hexagonal P6(3)cm structure. In contrast there exist several homeotypic phases with the general formula, Ln(1+n)Cu(n)MO(3+3n) (n = 1 (M = Ti), 2 (M = V) and 3 (M = Mo); Ln: lanthanide). Several YMn1-x(Cu3/4Mo1/4)(x)O-3 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. (c) 2005 Elsevier SAS. All rights reserved.