Designed Ferromagnetic,Ferroelectric Bi_2NiMnO_6

摘要

A newly designed ferromagnetic,ferroelectric compound,Bi_2NiMnO_6,was prepared by high-pressure synthesis at 6 GPa.The crystal structure,as determined by synchrotron X-ray powder diffraction,is a heavily distorted double perovskite with Ni~(2+) and Mn~(4+) ions ordered in a rock-salt configuration.The presence of 6s~2 lone pairs of Bi~(3+) ions and the covalent Bi-O bonds give ferroelectric properties with T_(CE) of 485 K,while -Ni~(2+)-O-Mn~(4+)-O-Ni~(2+)- magnetic paths lead to a ferromagnetism with T_(CM) of 140 K.This simple material design to distribute two magnetic elements with and without e_g electrons on B sites of Bi- and Pb-based perovkites can be applied to other Bi_2M~(2+)M~('4+)O_6 and Pb_2M~(3+)M~('5+)O_6 systems to search for newer ferromagnetic ferroelectrics.