Improved thermoelectric performance from CrSi₂ by Cu substitution into Si sites

We report herein the results of investigations into the thermoelectric properties of Cr(Si_{1- x} Cu _x )₂. In the Cu-content range x ≤ 0.04, single-phase Cr(Si_{1- x} Cu _x )₂ solid solution is obtained by arc melting and spark plasma sintering. With increasing Cu content, the electrical conductivity increases and the Seebeck coefficient decreases. Hall measurements confirm that the carrier concentration increases and the mobility decreases upon substituting Cu into Si sites. Cu substitution causes a significant decrease in the lattice thermal conductivity of CrSi₂ and enhances the maximum dimensionless figure of merit from z T = 0.16 at 600 K for x = 0 to z T = 0.23 at 900 K for x = 0.03. In addition, the temperature at which z T peaks increases from 600 to 900 K with increasing Cu content, which means that the operating temperature can be set by simply adjusting the Cu content.