Synthesis and Transport Properties of ‘334’ and Skutterudite Thermoelectric Compounds

Abstract

Various synthesis methods for thermoelectric compounds based on the family R\(_{3}\)Au\(_{3}\)Sb\(_{4}\) and the filled skutterudites LaRu\(_{4}\)Sb\(_{12}\) have been attempted and analyzed, and an improved method allowing crystals of phase pure samples suitable for doping experiments to be grown is presented. In both classes of compounds, doping experiments were subsequently carried out: in the 334 compounds by substituting different rare earth elements R, and Pt for Au, and in the skutterudites by substituting Rh for Ru. Transport measurements of the carrier concentration, resistivity, and Seebeck coefficient were carried out on each sample, including those grown during the synthesis development process. The performance of these measurements on the impure samples yielded important information helpful in developing the synthetic methods and determining the relationship between crystal structure and materials properties. Whereas, the properties determined on samples grown by the improved procedures were useful in determining the utility of these compounds as thermoelectric materials. The analysis presented shows that the compounds grown in this study will not serve well as thermoelectric materials, however some direction into future research on these compounds is given based on the understanding developed here.