| SrTiO3-based material is one of the best n-type oxide thermoelectric materials reported.However,the thermal conductivity of SrTiO3 matrix thermoelectric materials is too large,and the electrical conductivity decreases with the increase of temperature,which limit the application of SrTiO3 matrix thermoelectric materials at high temperatures.In this paper,based on SrTiO3 with doping 10 mol%La,micron powder and nano powder of TiB2 are introduced to prepare TiB2/La0.1Sr0.9TiO3 thermoelectric ceramics by a simple and feasible atmosphere sintering method and the carbon embedding sintering process.The effects of the powder size and adding amount of TiB2 on the composition,morphology,sintering performance and thermoelectric properties of La0.1Sr0.9TiO3 matrix thermoelectric ceramics were investigated,providing a new idea for the study of thermoelectric oxides.Firstly,La0.1Sr0.9TiO3 ceramic powder was prepared by a modified solid phase method,and micron powder with different concentration of TiB2 was combined to prepare TiB2/La0.1Sr0.9TiO3 thermoelectric ceramics by an atmosphere sintering method in 5%H2/95%Ar reduction atmosphere.The effects of sintering temperature(1200℃,1350℃,1500℃)and the adding amount of TiB2(1.25mass%,1.5mass%,2mass%,2.5mass%)on the composition,morphology,sintering performance and thermoelectric properties of La0.1Sr0.9TiO3 matrix thermoelectric ceramics were studied.The results showed that TiB2 composite effectively improved the sintering performance of La0.1Sr0.9TiO3 matrix thermoelectric ceramic samples,and reduced the sintering temperature to 1200℃.The power factor of 1.25mass%TiB2/La0.1Sr0.9TiO3 ceramics sintered at 1200℃ reached 359 W·m-1·K-2 at 500℃,and the ZT value reaches 0.082 at 500℃.Secondly,under the same processing conditions,different amounts of TiB2 nano powder were combined to prepare TiB2/La0.1Sr0.9TiO3 thermoelectric ceramics by the simple and feasible atmosphere sintering method,and the influence of adding 1.25mass%TiB2 nano powder on composition,morphology,sintering performance and thermoelectric properties of La0.1Sr0.9TiO3 matrix thermoelectric ceramics under different sintering temperatures(1200℃,1350℃)were studied.In addition,the results were compared with the La0.1Sr0.9TiO3 matrix thermoelectric ceramics with 1.25mass%TiB2 micron powder.The results showed that the adding nano-TiB2 reduced the number of pores,increased the grain size and the density of the sample.ZT value of La0.1Sr0.9TiO3 matrix thermoelectric ceramics sintered at 1350℃ with the adding nano-TiB2 powder,is larger than that of the sample sintered at 1200℃,and the largest ZT value is 0.088 at 500℃.Finally,the carbon burial sintering was adopted to inhibit the oxidative decomposition of TiB2 in the sintering process,and the effects of different carbon embedding atmospheres(a small amount of carbon,enough carbon)and the composite amount of TiB2(1.25mass%,12.5mass%)on the thermoelectric properties of La0.1Sr0.9TiO3 matrix thermoelectric ceramics were studied.The results showed that the carbon burial sintering effectively inhibited the oxidation decomposition of TiB2 in La0.1Sr0.9TiO3 matrix material during sintering,and avoided the over burning phenomenon,but it did not improve the thermoelectric properties of the material. |
