Thermoelectric properties of Ru2TiGe Heusler phase.

We report a study of structural, magnetic, heat capacity and thermoelectric properties of a Ru-based Heusler alloy, Ru 2 TiGe. The magnetic measurements reveal that at higher temperatures, diamagnetic and Pauli paramagnetic contributions dominate the magnetic behaviour whereas, at lower temperatures (T ≤ 20 K), superparamagnetic interaction among clusters is observed. The development of such magnetism, however, does not exhibit any noticeable influence in thermoelectric properties. Though the temperature dependence of electrical resistivity exhibits a metal-like nature, the large value of Seebeck coefficient leads to an appreciable power factor of the order of 0.54 mW/mK2 at 300 K. Large power factor as well as low thermal conductivity results in a value of zT = 0.025 at 390 K for Ru 2 TiGe that is orders of magnitude higher than that of the other pure Heusler alloys and point towards its high potential for practical thermoelectric applications. [Display omitted] • Ru 2 TiGe exhibits superparamagnetism despite having no magnetic element and VEC 24. • Low thermal conductivity due to heavier element induced enhancement of e-ph and phph scattering. • Highest zT among pristine full-Heusler alloys, despite exhibiting metal-like conductivity. [ABSTRACT FROM AUTHOR]