Thermoelectric properties of Ti-doped SiC/TiCx composite synthesized by TPPP method

To improve thermoelectric properties, we attempt to dope Ti into SiC-based composite by transient plastic phase process (TPPP) method. The final resul t is composed of the functional phase SiC and the reinforcement phases TiCx and TiSi2. The process of doping is the diffusion of Ti in TICx solid-solu tion into SiC grain at high temperature. When the initial SiC is alpha-type of 5 mu m size, the Seebeck coefficient S is less than 10 mu V/K at room t emperature. SEM photograph shows the reason being that doping is very weak. We change the initial SiC to the beta-type of 90 nm size to aid doping. It is observed that S can be significantly improved to 46.3 mu V/K at room te mperature. When the temperature rises, the improvement is even greater. Mea surements of the lattice parameter of beta-SiC show that the parameter para llel to the Si-C layer is almost unchanged and the parameter perpendicular to the Si-C layer increases by about 0.48%, which demonstrated that Ti has been successfully doped into the SiC grain and exists as interstitial impur ities.