The composition and carrier concentration variations of the thermoelectric properties of the binary narrow-gap compound Ga67-xRu33+x have been investigated. The measured samples were synthesized by a combination of arc-melting and spark plasma sintering (SPS), succeeded in crack-free samples. We report that the temperature dependences of the electrical resistivity and Seebeck coefficient of the Ga67-xRu33+x are strongly affected by nominal Ru concentration. The Seebeck coefficients showed large positive values from 170 to 350 μV K-1 at 373 K. Also, large power factors from 2.2 to 3.0 mW m-1 K-2 were obtained at 773 K. The dimensionless figures of merit ZT beneficially increased with increasing temperature and reached a maximum value of 0.50 at about 773 K.
- Narrow-band-gap semiconductor
- Nowotny chimney-ladder phase
- Ruthenium gallide
- Spark plasma sintering
- Thermoelectric material