Electrical Properties of Microwave-Sintered (Sr0.4Pb0.6)TiO3 Ceramics

概要

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The resistivity-temperature (ρ-T) characteristics of the (Sr0.4Pb0.6)TiO3 materials prepared by a microwave sintering process were examined. The resistivities were significantly lowered by increasing the rate of cooling and were substantially increased by a heat-treatment process. The Curie temperature was not altered by a fast cooling process but was shifted from T c=302° C to 210° C when the as-sintered samples were post-heat-treated at 1200° C for 1 h. The high Curie temperature of the as-sintered samples was proposed to be due to the core-shell structure of the grains. The "shell", which contained Pb-rich perovskite of the composition (Sr0.29Pb0.71)TiO3, was homogenized with core material during heat treatment. The variation in resistivity was ascribed to the modification of the concentration of cationic vacancies. The donor level (E d) and the deep trap level (E t) of the materials were, respectively, evaluated from the Arrhenius plot of ρ-T characteristics at T<T c and T>T max regimes to be E d≈0.078–0.193 eV and $E_{\rm t}\cong 1.66\,\mbox{eV}+E_{\rm f}$, where E f is the Fermi level.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
1996-02-15