Effects of Al doping on the thermoelectric performance of CoSi single crystal

Thermoelectric transport properties of CoSi1−xAlx single crystals have been measured over the temperature range from 300to973K to investigate the effects of Al substitution on the electrical resistivity, Seebeck coefficient, and thermal conductivity. The solubility limit of Al substitution for Si in CoSi is found to be in the range of 0.2⩽x<0.3. The electrical resistivity increases with increasing Al substitution x and reaches a maximum at x=0.08. When x is further increased, there is a drop in the electrical reisitivity between 300 and 550K and there is almost no change at higher temperatures. The Seebeck coefficients of CoSi1−xAlx single crystals shift towards the positive direction compared to that of the binary crystal over the entire measured temperature range. The Seebeck coefficient decreases as a function of temperature. The thermal conductivity and the figure of merit decrease significantly with increasing Al content. The decrease in thermal conductivity is mainly attributed to the additional scattering from Al atoms.