Abstract
In this work, we obtain (Ba 0.7 Pb 0.3 )TiO 3 materials possessing double critical temperature T c 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-T c resistivity jumps without altering the T c values. The donor E d and trap E s levels of those materials are estimated to be E d ≅0.05-0.07 eV and E s ≅1.07-1.32 eV. According to experimental results the voltage sensitivity and transient responsivity of the current passing through double-T c materials are observed to be superior to those of single-T c materials prepared by the conventional furnace sintering method. Also, the double-T c , 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. © 1996 American Institute of Physics.