Effects of Nb-substitution on structure, dielectric, ferroelectric and magnetic properties of Ba4Nd2Fe2Ta8O30 ceramics

Effects of Nb-substitution on crystal structure, dielectric, ferroelectric and magnetic properties of Ba4Nd2Fe2Ta8O30 ceramics were investigated. With the increase of x, Ba4Nd2Fe2(NbxTa1−x)8O30 ceramics transform from paraelectric to ferroelectric. The compositions x=0.9 and 0.95 show diffuse-type ferroelectric phase transition with Tc above room temperature (306 K for x=0.9 and 320 K for x=0.95). For x=0 and 0.5, Ba4Nd2Fe2(NbxTa1−x)8O30 ceramics are paramagnetic at room temperature. From x=0.7 to x=0.95, the remnant moment of Ba4Nd2Fe2(NbxTa1−x)8O30 ceramics increases with increasing x. Magnetic hysteresis loops for x=0.7-0.95 at room temperature were obtained and could be ascribed to the tungsten bronze structure per se. The Ba4Nd2Fe2(NbxTa1−x)8O30 ceramics with x=0.9 and 0.95 are single-phase multiferroics at room temperature.