Dielectric abnormities of complex perovskite Ba(Fe1/2Nb1/2)O3 ceramics over broad temperature and frequency range

Dielectric characteristics of Ba(Fe1/2Nb1/2)O-3 ceramics were investigated over a broad temperature and a frequency range. Two dielectric relaxations following Arrhenius law were observed at 150-400 and 406-650 K. An extremely high relaxorlike dielectric peak (202 270 at 5 Hz, 91 930 at 1 kHz, and 37 030 at 100 kHz) with very strong frequency dispersion was observed at 406-650 K, and it was not relaxor ferroelectric but an oxygen defect induced dielectric abnormity. The significant drop of dielectric constant at 146-400 K was also frequency dependent, and it was nearly a Debye relaxation. Between these two dielectric relaxations, there was a frequency dependent dielectric constant plateau over a wide temperature interval. (c) 2007 American Institute of Physics.