Abstract
PTCR materials with very high critical temperature (T c =420 °C ) have been prepared by microwave sintering technique with the composition (Pb 0.6 Sr 0.3 Ba 0.1 )TiO 3 . Incorparation of SiO 2 as sintering aids has lowered the sintering temperature required from 1250 °C (10 min) to 1140 °C (10 min) and stabilized the electrical properties. The resistivity ratio, and minimum resistivity achieved for these samples were ρ max/ ρ min ≈10 2 85 ∼10 3.2 ohm-cm and ρ min ≈ 10 2 ohm-cm, respectively. The electronic parameters such as donor level (ε d ∼0.077 eV), PTCR jump and trap level (ε a ∼0.70 eV+ ε F ) were found to be the better parameters to indicate the perfecness of the densification process than the crystal structures and the microstructure examinations.