Enhanced multiferroicity in Mn- and Cu-modified 0.7BiFeO_3-0.3(Ba_(0.85)Ca_(0.15))TiO_3 ceramics

摘要

The effect of CuO and MnO_2 as sintering additives on the structural, ferroelectric, and magnetic properties of 0.7BiFeO_3-O.3(Ba_(0.85)Ca_(0.15))TiO_3 was investigated. The addition of CuO can inhibit grain growth, and the sample possesses the maximum remanent magnetization. However, the addition of MnO_2 can promote grain growth, and the sample exhibits the maximum remanent polarization of 34μC/cm~2. Nevertheless, the addition of both CuO and MnO_2 can markedly enhance the magnetic properties. The magnetization measurements manifest that all the samples undergo a paramagnetic to ferrimagnetic transition arising from the existence of a net moment due to the antiferrimagnetic interactions between Fe~(2+) and Fe~(3+) sublattices. The enhanced magnetism of the samples with the addition of CuO and MnO_2 can be due to the enhanced superexchange interaction between Fe~(2+) and Fe~(3+) arising from the increased Fe-O-Fe bond angle.