Synthesis of Thermoelectric SrTiO₃ Ceramics by the Polymerized Complex Process and Pulsed Current Heating Method

Abstract

The establishment of rapid synthesis process at a low temperature of thermoelectric SrTiO₃ was tried by using the polymerized complex (PC) process and the pulsed current heating (PCH) method. The non-doped and La- or Y- doped SrTiO₃ powders could be synthesized by the PC process without precipitation of any second phase. The densely sintered bulks could also be obtained from these powders by the PCH method at 1473 or 1573 K for 5 min. In order to reduce electrical resistivity, TiB₂ powder was added to the Y-doped SrTiO₃. During the sintering, any reaction between SrTiO₃ phase and TiB₂ powder did not occur, resulting in the formation of Sr_1-xY_xTiO₃/TiB₂ composites. The TiB₂ addition was quite effective not only for reduction in the electrical resistivity, but also for rapid densification during the sintering. The power factor of the Sr_1-xY_xTiO₃/TiB₂ composites over 800 K was similar to that of the Sr_0.9Y_0.1TiO₃ polycrystal synthesized by the conventional solid state reaction method, indicating that the synthesis route via the PC process, the PCH method and TiB₂ addition is quite promising as a rapid synthesis process at a low temperature of the thermoelectric SrTiO₃ system.