Alloying and doping control in the layered metal phosphide thermoelectric CaCuP
Abstract
We recently identified CaCuP as a potential low cost, low density thermoelectric material, achieving zT = 0.5 at 792 K. Its performance is limited by a large lattice thermal conductivity, κL, and by intrinsically large p-type doping levels. In this paper, we address the thermal and electronic tunability of CaCuP. Isovalent alloying with As is possible over the full solid solution range in the CaCuP1–xAsx series. This leads to a reduction in κL due to mass fluctuations but also to a detrimental increase in p-type doping due to increasing Cu vacancies, which prevents zT improvement. Phase boundary mapping, exploiting small deviations from 1:1:1 stoichiometry, was used to explore doping tunability, finding increasing p-type doping to be much easier than decreasing the doping level. Calculation of the Lorenz number within the single parabolic band approximation leads to an unrealistic low κL for highly doped samples consistent with the multiband behavior in these materials. Overall, CaCuP and slightly Cu-enriched CaCu1.02P yield the best performance, with zT approaching 0.6 at 873 K.
Citation
Quinn , R , Biswas , R & Bos , J-W G 2024 , ' Alloying and doping control in the layered metal phosphide thermoelectric CaCuP ' , ACS Applied Electronic Materials , vol. 6 , no. 5 , pp. 2879–2888 . https://doi.org/10.1021/acsaelm.3c00828
Publication
ACS Applied Electronic Materials
Status
Peer reviewed
ISSN
2637-6113Type
Journal article
Description
Engineering and Physical Sciences Research Council - EP/R023751/1, EP/T019298/1, EP/W037300/1; Leverhulme Trust - RPG-2020-177Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.