Effect of barium doping on the microstructure, dielectric and magnetic properties of GdMnO_3 multiferroic ceramics

摘要

Undoped GdMnO3 (GMO) and Gd0.95Ba0.05MnO3 (GBMO) multiferroic ceramics were prepared by solid state reaction method, and the effects of Ba doping on the structure, morphology, dielectric and magnetic properties of GMO system were investigated. The XRD results show that the two samples yield single phase, and Ba doping induce structure distortion. The SEM images show that Ba doping can inhibit the grain growth. The XPS analysis indicates that more Mn4+ and oxygen vacancies are involved in the Ba doped GMO ceramics. Raman measurements show that Ba substitutes Gd into the lattice of GMO and induces lattice disorder. The dielectric measurements reveal that the Ba doped GMO exhibits the giant dielectric properties, but the dielectric loss of Ba doped samples is higher than that of the undoped samples. Temperature and magnetic field dependent magnetization measurements reveal that the low temperature magnetic behaviors of GMO system can be altered by Ba doping. The paramagnetic-antiferromagnetic transition temperature and magnetization of GMO system are decreased after Ba doping. In addition, Ba doping can also influence the long-range order of Gd moments at about 8K. The possible reasons for the above results are discussed.