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High Thermopower with Metallic Conductivity in p-Type Li-Substituted PbPdO2

Published

Author(s)

Leo K. Lamontagne, Geneva Laurita, Michael W. Gaultois, Michael Knight, Leila Ghadbeigi, Taylor D. Sparks, Markus E. Gruner, Rossitza Pentcheva, Craig Brown, Ram Seshadri

Abstract

PbPdO2 is a band semiconductor with a band gap arising from the filled d8 nature of square-planar Pd2+. We establish that hole doping through Li substitution for Pd in PbPdO2 results in a p-type metallic oxide with a positive temperature coefficient of resistance for substitution amounts as small as 2 mol % of Li for Pd. Furthermore, PbPd1-xLixO2 demonstrates a high Seebeck coefficient, and is therefore an oxide thermoelectric material with high thermopower despite the metallic conductivity. Up to 4 mol % Li is found to substitute for Pd as verified by Rietveld refinement of neutron diffraction data. At this maximum Li-substitution, the resistivity is driven below the Mott metallic maximum to 3.5x10-3Ω} cm with a Seebeck coefficient of 115υV/K at room temperature which increases to 175 υV/K at 600 K. These electrical properties are almost identical to the well-known p-type oxide thermoelectric NaxCoO2. In contrast to the cobalt oxides, non-magnetic LI-substituted PbPdO2 does not possess the spin entropy responsible for the high performance in the cobaltate compounds. This suggests that there are other avenues to achieving high Seebeck coefficients in oxide thermoelectrics. The electrical properties coupled with the moderately low lattice thermal conductivities allow for a zT = 0.12 at 600 K, the maximum temperature measured here. The trend suggests yet higher values at elevated temperatures.
Citation
Chemistry of Materials
Volume
28
Issue
10

Keywords

thermoelectric, neutron diffraction, substitution, structre

Citation

Lamontagne, L. , Laurita, G. , Gaultois, M. , Knight, M. , Ghadbeigi, L. , Sparks, T. , Gruner, M. , Pentcheva, R. , Brown, C. and Seshadri, R. (2016), High Thermopower with Metallic Conductivity in p-Type Li-Substituted PbPdO<sub>2</sub>, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919970 (Accessed May 22, 2024)

Issues

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Created May 8, 2016, Updated October 12, 2021