The influences of Na and K content on the crystal phase, the microstructure and the electrical property of BaTiO3-based thermistors was found to show typical PTC effects. The crystal phase of powder calcined at 1000˚C for 4hrs showed a single phase with BaTiO3, and the crystal structure was transformed from tetragonal to cubic phase according to added amounts of Na and K. In XRD results at 43˚~47˚, the (Ba0.858Na0.071K0.071)(Ti0.9985Nb0.0015)O3-δ showed (002) and (200) peaks but the (Ba0.762Na0.119K0.119)(Ti0.9975Nb0.0025)O3-δ showed (002), (020) and (200) peaks. In sintered bodies, those calcined at 600˚C rather than at 1000˚C were dense, and for certain amounts of Na and K showed rapid decreases in grain size. In relative permittivity, the curie temperature due to the transformation of ferroelectric phase rose with added Na and K but decreased in terms of relative permittivity. In the result of the R-T curve, the sintered bodies have curie temperatures of about 140˚C and the resistivity of sintered bodies have scores of Ω·cm; the jump order of sintered bodies was shown to be more than 104 in powder calcined at 1000˚C.

CoSb3 Skutterudites materials have high potential for thermoelectric application at mid-temperature range because of their superior thermoelectric properties via control of charge carrier density and substitution of foreign atoms. Improvement of thermoelectric properties is expected for the ternary solid solution developed by substitution of foreign atoms having different valances into the CoSb3 matrix. In this study, ternary solid solutions with a stoichiometry of Co1-xNixSb3 x = 0.01, 0.05, 0.1, 0.2, CoSb3-yTey, y = 0.1, 0.2, 0.3 were prepared by the Spark Plasma Sintering (SPS) system. Before the SPS synthesis, the ingots were synthesized by vacuum induction melting and followed by annealing. For phase analysis X-ray powder diffraction patterns were checked. All the samples were confirmed as single phase; however, with samples that were more doped than the solubility limit some secondary phases were detected. All the samples doped with Ni and Te atoms showed a negative Seebeck coefficient and their electrical conductivities increased with the doping amount up to the solubility limit. For the samples prepared by SPS the maximum value for dimensionless figure of merit reached 0.26, 0.42 for Co0.9Ni0.1Sb3, CoSb2.8Te0.2 at 690 K, respectively. These results show that the SPS method is effective in this system and Ni/Te dopants are also effective for increasing thermoelectric properties of this system.