High thermoelectric performance of bornite through control of the Cu(II) content and vacancy concentration

Long, S. O. J., Powell, A. V., Vaqueiro, P. ORCID: https://orcid.org/0000-0001-7545-6262 and Hull, S. (2018) High thermoelectric performance of bornite through control of the Cu(II) content and vacancy concentration. Chemistry of Materials, 30 (2). pp. 456-464. ISSN 1520-5002 doi: 10.1021/acs.chemmater.7b04436

Abstract/Summary

The thermoelectric performance of the p-type semiconductor bornite, Cu5FeS4, is greatly enhanced through chemical substitution. Non-stoichiometric materials in which the Cu:Fe ratio and overall cation-vacancy con-tent were adjusted are reported and a figure of merit, ZT = 0.79, is achieved at temperatures as low as 550 K in Cu4.972Fe0.968S4. All materials were synthesised mechanochemically and characterised by powder X-ray diffrac-tion, DSC and thermal and electrical transport property measurements. Single-phase behaviour is retained in copper deficient phases, Cu5-xFeS4, for vacancy levels up to x = 0.1, while in materials Cu5+yFe1-yS4, in which the Cu:Fe ratio is varied whilst maintaining full occupancy of cation sites, single-phase behaviour persists for y≤0.08. Adjusting the Cu:Fe ratio at a constant cation-vacancy level of 0.06 in Cu4.94+zFe1-zS4, leads to single-phases for z ≤0.04. DSC measurements indicate the temperature of the intermediate- (2a) to high-temperature (a) phase transition shows a more marked dependence on the Cu:Fe ratio than the lower temperature 4a to 2a transition. The thermoelectric power factor increases almost linearly with increasing Cu(II) content. The maximum figures of merit are obtained for materials with Cu(II) contents in the range 0.10 to 0.15 (corresponding to 2.0 – 2.8 % Cu(II)) which simultaneously contain ca .1 % of cation vacancies.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/74428
Identification Number/DOI	10.1021/acs.chemmater.7b04436
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry Interdisciplinary centres and themes > Energy Research Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Thermal Analysis (CAF) Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Xray (CAF) Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Electron Microscopy Laboratory (CAF)
Publisher	American Chemical Society
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