Dielectric properties of stabilized barium titanate films

Barium titanate, because of its exceptionally high dielectric constant, has been used extensively as a capacitor material. It, however, possesses two undesirable characteristics, namely decreased insulation resistance(degradation) under high de voltage stresses at temperatures in excess of the Curie point of 120 [degrees C] and a high-temperature coefficient of capacitance near the Curie point. In the present investigation improvement in life-time were achieved by the incorporation of lanthanum oxide inter barium titanate. Films of composition 99 mole % BatiO(3) and 0.3 mole % La2O3 were prepared by the sol-gel method using metal alkoxodes, and tested for high-temperature stability, It was found that the resistance of barium titanate to the degradation of dielectric properties can be improved by the incorporation of small quantities(0.1 similar to 0.5 mole %) of La2O3. A survey of dielectric properties for compositions forming lanthanum-barium titanate solid solutions indicated that the temperature coefficient of capacitance and dissipation factor can be reduced to quite low values for certain compositions along the join BatiO(3)-La2O3. The compositions containing 0.3 mole % La2O3 exhibit the most satisfactory dielectric properties but abbreviated lifetimes.