Investigation of Novel Europium-based Zintl Phases for Thermoelectric Applications

Download or read book Investigation of Novel Europium-based Zintl Phases for Thermoelectric Applications written by Joya Ashley Cooley and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric (TE) devices are those that can convert waste heat to electricity in power generation mode, or convert a current to a thermal gradient to provide selective cooling in refrigeration mode. These devices present viable options for power generation that make no noise, contain no moving parts or toxic liquids, and emit no harmful gases. Performance of a thermoelectric material generally scales with its dimensionless figure-of-merit, zT. zT (=S2T/p[kappa], where S is the Seebeck coefficient, [rho] is the electrical resistivity, and [kappa] is thermal conductivity) can be maximized by lowering thermal conductivity and electrical resistivity while maximizing the Seebeck coefficient. An ideal thermoelectric material with high zT, then, must achieve an unusual mix of properties with high electronic conduction, but low thermal conduction. In recent years, researchers have looked to Zintl phases as viable candidates to achieve this mixture of properties. Zintl phases, a subset of intermetallic compounds, provide an interesting avenue for exploration of thermoelectric materials because their complex structures – consisting of polyanionic networks hosting isolated cations – inherently separate electronic transport from thermal transport. Additionally, the marriage of covalent and ionic interactions in Zintl phases allows for selective tuning of electronic and thermal properties toward optimization, so each parameter can theoretically be tuned independently. New structure types and solid solutions thereof have been revolutionary to the thermoelectric field because they assist in understanding the relationship between the Zintl structures and the properties they exhibit. Presented herein are several europium-based Zintl phases for thermoelectric applications including their syntheses, characterization, physical property measurement, and analysis of structure-property relationships.