Ferroelectric and dielectric properties of sol-gel processed barium titanate ceramics and thin films

Ferroelectric and dielectric properties of barium titanate (BaTiO3) bulk ceramics and thin films have been investigated. The bulk ceramics and thin film samples have been prepared from barium acetate [Ba(CH3COO)(2)] and titanium(lv)isopropoxide [Ti(CH3)(2)CHO)(4)] precursors by sol-gel technique. The as-grown bulk powder and thin films were found to be amorphous, which crystallized to tetragonal phase after annealing at 700 degrees C in air for one hour. The values of the spontaneous polarization (P-s), remanant polarization (P-r) and coercive field (E-c) of the bulk ceramics were found to be 19.0, 12.6 mu C cm(-2) and 30 kV cm(-1) respectively. In the case of the film, the values of P-s, P-r and E-c were respectively found to be 14.0, 3.2 mu C cm(-2) and 53 kV cm(-1). The capacitance-voltage (C-V) characteristics of the film also showed polarization hysteresis. The values of the dielectric constant (epsilon) of the bulk ceramic and thin film at 1 kHz were found to be 1235 and 370 respectively. Both the films and ceramics showed dielectric anomaly peaks at 125 degrees C, showing ferroelectric to paraelectric phase transition. (C) 1999 Kluwer Academic Publishers.