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Title: Phase transition enhanced thermoelectric figure-of-merit in copper chalcogenides

While thermoelectric materials can be used for solid state cooling, waste heat recovery, and solar electricity generation, low values of the thermoelectric figure of merit, zT, have led to an efficiency too low for widespread use. Thermoelectric effects are characterized by the Seebeck coefficient or thermopower, which is related to the entropy associated with charge transport. For example, coupling spin entropy with the presence of charge carriers has enabled the enhancement of zT in cobalt oxides. We demonstrate that the coupling of a continuous phase transition to carrier transport in Cu{sub 2}Se over a broad (360–410 K) temperature range results in a dramatic peak in thermopower, an increase in phonon and electron scattering, and a corresponding doubling of zT (to 0.7 at 406 K), and a similar but larger increase over a wider temperature range in the zT of Cu{sub 1.97}Ag{sub .03}Se (almost 1.0 at 400 K). The use of structural entropy for enhanced thermopower could lead to new engineering approaches for thermoelectric materials with high zT and new green applications for thermoelectrics.
Authors:
; ;  [1] ; ; ;  [2]
  1. Department of Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125 (United States)
  2. Department of Chemistry and iNano, Aarhus University, Aarhus 8000 (Denmark)
Publication Date:
OSTI Identifier:
22269586
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 1; Journal Issue: 5; Other Information: (c) 2013 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COBALT OXIDES; COOLING; COPPER; COPPER SELENIDES; EFFICIENCY; ENTROPY; PHASE TRANSFORMATIONS; SOLIDS; TEMPERATURE RANGE; THERMOELECTRIC MATERIALS; WASTE HEAT