Room temperature multiferroic Ba4Bi2Fe2Nb8O30: Structural, dielectric, and magnetic properties

A room temperature multiferroic compound Ba4Bi2Fe2Nb8O30 was synthesized using a solid state reaction technique. Rietveld analysis of x-ray diffraction data shows that Ba4Bi2Fe2Nb8O30 has a tetragonal (space group P4bm) tungsten bronze structure. In this structure, the Fe3+ and Nb5+ statistically occupy the octahedral center while the Ba2+ ions and the Bi3+ ions occupy the pentagonal channels and the square channels, respectively. Diffuse dielectric peaks with strong frequency dispersion in the temperature range from 150 to 300 K can be attributed to the random distribution of Fe3+ and Nb5+ at B sites. Magnetic hysteresis loop at room temperature is also obtained, which suggests that Ba4Bi2Fe2Nb8O30 is a room temperature multiferroic compound. The coupling between the relaxor behavior and magnetic ordering is verified by observing an increase of magnetization near the maximum dielectric constant temperature. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3459887]