Microstructure and Electrical Properties of Niobium Doped Barium Titanate Ceramics

The effects of Nb addition on phase, microstructure and electrical properties of barium titanate ceramicswere investigated. Nb-doped barium titanate ceramics (BaTi1-xNbx)O-3, x = 0 to 0.02) were prepared by conventional mixed-oxide method. All barium titanate compositions show tetragonal perovskite structure. Low Nb concentration (x = 0.005) results in abnormal grain growth in barium titanate. However, the grain size becomes uniform and decreases as Nb content increases, suggesting Nb inhibits grain growth in the studied composition range. The dielectric constant increases as the amount of Nb increases. The temperature of tetragonal to cubic phase transition shifts to lower temperature and the temperature curves become broadening with increasing of Nb content. Measurement of ferroelectric P-E hysteresis loop at 50 Hz and applied electric field of 15 kV shows that the remanent polarization of barium titanate ceramics tends to decrease as Nb content increases. Change in dielectric properties and the P-E hysteresis loop did not show large aging effect in the Nb-doped barium titanate ceramics.