To improve thermoelectric properties, we attempt to dope Ti into SiC-based composite by transient plastic phase process (TPPP) method. The final result is composed of the functional phase SiC and the reinforcement phases TiC x and TiSi 2. The process of doping is the diffusion of Ti in TiC x solid–solution into SiC grain at high temperature. When the initial SiC is α-type of 5 μm size, the Seebeck coefficient S is less than 10 μV/K at room temperature. SEM photograph shows the reason being that doping is very weak. We change the initial SiC to the β-type of 90 nm size to aid doping. It is observed that S can be significantly improved to 46.3 μV/K at room temperature. When the temperature rises, the improvement is even greater. Measurements of the lattice parameter of β- SiC show that the parameter parallel 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 impurities.
High Temperature Thermoelectric Properties of the Solid-Solution Zintl Phase Eu11Cd6–xZnxSb12
