Thermoelectric properties of high temperature transition metal silicides prepared by spark plasma sintering method

From the viewpoint of the most efficient utilization of fossil fuel resources as heat, the combustion temperature should be as high as possible to apply to the energy cascading system. Therefore, thermoelectric energy conversion as a topping system is recognized to be very important. High temperature metal silicides such as chromium silicide (M.P. 1763 K) and tungsten silicide (M.P. 2433 K) and so on have been known as a group of metal silicides. The spark plasma sintering method was selected to prepare thermoelectric elements of chromium silicide and tungsten silicide as examples of the high temperature, transition metal silicides. It is clarified that the spark plasma sintering method is very useful to make such a high temperature alloy. The temperature dependence of thermoelectric properties such as the Seebeck coefficient, electrical resistivity, power factor, thermal conductivity, carrier concentration and Hall mobility was measured to find out the preferable preparation conditions such as doping level and solid solution for these materials systems. The maximum power factor was 0.7/spl times/10/sup -02/ W/mK/sup 2/ at 900 K for chromium silicide, and 3.0/spl times/10/sup -02/ W/mK/sup 2/ at 1000 K for tungsten silicide as the p-type thermoelectric element respectively in the experiment.