Novel Ge-Sb-Te thermoelectric materials: A demonstration for an efficient diffusion couple technique in expediently exploiting new thermoelectric materials

Abstract

Abstract An efficient diffusion couple technique is proposed for rapid screening of potential thermoelectric materials and it has been explored in a (GeTe)m (Sb2Te3)n pseudobinary system. In this study, a combinatorial sample library of GeTe-Sb2Te3 diffusion couple with rich compositions and structures was prepared by plasma activation sintering (PAS). The relationship among composition, structure and performance of the materials was revealed by analyzing the chemical composition, crystal structure and thermoelectric properties of the microdomains in the combinatorial sample library, so as to achieve the purpose for rapid identification of Ge-Sb-Te compounds with excellent thermoelectric properties. The scanning results of the Seebeck coefficient of the samples library show that the sample with potential high thermoelectric performance has a chemical composition near Ge33.1Sb13.7Te53.2. The bulk materials with compositions in the vicinity of Ge33.1Sb13.7Te53.2 were prepared by a conventional melting and PAS process. Among these bulk samples, the one with a nominal composition of Ge38Sb10.3Te51.7 achieves a maximum ZT value of 0.55 at 673 K, indicating that the constituent phases Ge0.77Sb0.154Te1 and Ge3.37Sb1.63Te6 observed in this sample could be potential candidates with excellent thermoelectric properties. These two ternary compounds should be investigated for further optimization. The results of this study provide a reference for the application of combinatorial metrology for screening and optimizing new thermoelectric materials.