Structures, properties, and potential applications of rare earth-noble metal tellurides

Abstract

As many nations continue to develop and industrialize, the global energy demands are rising rapidly. With the threat of climate change disaster looming, the search for sustainable, “green” energy has become of higher priority. Thermoelectric materials add an important facet to the mosaic of future energy plans by allowing the scavenging of (“low-quality” waste) heat created through other processes and their transformation back into useful electrical energy. Thermoelectrics (similar to other green energy sources like solar cells) have struggled to reach high enough efficiencies to allow their cost-effective widespread implementation. Thus, the search for new thermoelectric materials has gained momentum.This review covers the growing family of rare earth metal (R: Sc, Y, and La-Lu)-noble metal (M: Cu, Ag, Au, Pd and Pt)-tellurides which are an interesting group of materials in the discussed context. Rare earth metal-noble metal tellurides constitute an increasing family of structures, numbering nearly forty unique structure types and including quaternary and quinary compounds. Structures include 1D channel structures, 2D layered slab structures, and complex 3D networks. R-M-Te compounds provide a wide variety of p-type semiconducting materials to choose from. The effectiveness of these structures as thermoelectric materials range in utility, with most showing maximum performance (figure of merit, zT – see below) values in the mid to high temperature ranges. To date, this culminates in the highest zT for this family with TbCuTe2, zT = 1.0 at 750 K, which still has potential for optimization. Albeit most observed compounds have been structurally quite well characterized, for many a thorough investigation of their physical properties, be it transport or magnetism is lacking. This work strives to combine, analyze, and at times untangle the variety of structures and properties reported across the breadth of research on this family.