Doping influence on the stability of YMnO_3 orthorhombic perovskite obtained by mechanosynthesis

摘要

Orthorhombic perovskite solid solutions with YMn_(1-x)Ni_xO_3 and YMn_(1-x)Ni_xO_3 compositions (x = 0,0.05, 0.10, 0.15) have been prepared by mechanosynthesis from a mixture of oxides in a planetary mill. This method allows the use of high-pressure and high-temperature route to be avoided, which is the habitual method to prepare rare-earth manganites with small ionic radius. The high energy supplied by the milling induces the synthesis of the perovskite oxides with a high distortion due to the Jahn-Teller effect. The stability of the structure with temperature is increased with small amounts of Ni proving that the influence of the Jahn-Teller effect is more important than that of the tolerance factor on the stability of the perovskite polymorph. Such stability is not achieved by Co substitution, as this doping is not so efficient in the formation of Mn~(4+), non-Jahn-Teller cations. Magnetic studies were carried out to determine the properties of the materials obtained by this route.