HIGH T-C POSITIVE TEMPERATURE-COEFFICIENT RESISTIVITY (PB0.6SR0.3BA0.1)TIO3 MATERIALS PREPARED BY MICROWAVE SINTERING

PTCR materials with very high critical temperature (T-c=420 degrees C) have been prepared by microwave sintering technique with the composit ion (Pb0.6Sr0.3Ba0.1)TiO3. Incorparation of SiO2 as sintering aids has lowered the sintering temperature required from 1250 degrees C (10 mi n) to 1140 degrees C (10 min) and stabilized the electrical properties . The resistivity ratio, and minimum resistivity achieved for these sa mples were rho(max)/rho(min) approximate to 10(2.85) similar to 10(3.2 ) ohm-cm and rho(min) approximate to 10(2) ohm-cm, respectively. The e lectronic parameters such as donor level (epsilon (d) similar to 0.077 eV), PTCR jump and trap level (epsilon(a) similar to 0.70 eV + epsilo n(F)) were found to be the better parameters to indicate the perfecnes s of the densification process than the crystal structures and the mic rostructure examinations.