Thermoelectric properties of Mn-doped Ru/sub 2/Si/sub 3/

Pure and Mn-doped single crystals of ruthenium silicide (Ru/sub 2/Si/sub 3/) have been grown by floating zone technique with radiation heating in order to investigate the thermoelectric efficiency of this compound. Electrical resistivity, Hall effect, Seebeck coefficient and thermal conductivity of the crystals were measured at 100 - 900 K. Undoped crystals show in the thermoelectric power both types of conductivity. The Seebeck coefficient of Ru/sub 1-x/Mn/sub x/Si/sub 1.5/ is positive in the whole temperature range studied and reaches the maximum value of 450 /spl mu/V/K at about 500 K. The room temperature value of 300 /spl mu/V/K is twice higher in magnitude than the corresponding value for the undoped Ru/sub 2/Si/sub 3/. The charge carrier concentration in the 1% Mn-doped samples is about 10/sup 18/cm/sup -3/ at room temperature and the Hall mobility is about 20 cm/sup 2//V/spl middot/s. The comparison with the undoped Ru/sub 2/Si/sub 3/ shows a twofold increase of the carrier mobility as the result of doping. The performed theoretical calculation of the carrier mobility is based on the effective masses, which are estimated from the ab initio electronic band structure and classical scattering mechanisms. The mobility as well as thermoelectric properties show a reasonable agreement with the experimental data for both Mn-doped and undoped Ru/sub 2/Si/sub 3/ crystals.