DOUBLE CRITICAL TEMPERATURE CHARACTERISTICS OF SEMICONDUCTING (BA0.7PB0.3)TIO3 MATERIALS PREPARED BY MICROWAVE SINTERING

In this work, we obtain (Ba0.7Pb0.3)TiO3 materials possessing double critical temperature Tc in resistivity–temperature (ρ–T) behavior by microwave sintering at 1050–1080 °C for 5 min. The cooling‐rate control and postannealing processes modify the relative magnitudes of low‐ and high‐Tc resistivity jumps without altering the Tc values. The donor Ed and trap Es levels of those materials are estimated to be Ed≂0.05–0.07 eV and Es≂1.07–1.32 eV. According to experimental results the voltage sensitivity and transient responsivity of the current passing through double‐Tc materials are observed to be superior to those of single‐Tc materials prepared by the conventional furnace sintering method. Also, the double‐Tc characteristics are attributed to the dual phases with a core‐shell structure. Moreover, the change in the relative proportion of the two phases accounts for the influence of post‐heat treatment processes on the materials’ ρ–T behavior.