High figure of merit in nanostructured n-type KPb{sub m}SbTe{sub m+2} thermoelectric materials.
- Materials Science Division
We demonstrate that the KPb{sub m}SbTe{sub 2+m} system (PLAT-m for tellurium, antimony, lead potassium, m = 19-21) of materials exhibits high thermoelectric performance. Samples with compositions K{sub 1-x}Pb{sub m+{delta}}Sb{sub 1+{gamma}}Te{sub m+2} were prepared using several combinations of x, {delta}, {gamma} and m and their thermoelectric properties were investigated in the temperature range of 300-800 K. All K{sub 1-x}Pb{sub m+{delta}}Sb{sub 1+{gamma}}Te{sub m+2} samples exhibited n-type conduction over the measured temperature range. Their lattice thermal conductivities were found to be significantly reduced when compared to PbTe and even AgPb{sub m}SbTe{sub m+2}. For example, for K{sub 0.95}Pb{sub 20}Sb{sub 1.2}Te{sub 22} a lattice thermal conductivity as low as 0.4 W/(m {center_dot} K) was estimated at 650 K (based on a Lorenz number of 1.25 x 10{sup -8} W {center_dot} {Omega}/K{sup 2}). High resolution transmission electron microscopy on several samples revealed a widely dispersed nanoscale particle with varying size and shape endotaxially embedded inside a PbTe-rich matrix which is believed to be responsible for the reduced lattice thermal conductivity of K{sub 1-x}Pb{sub m+{delta}}Sb{sub 1+{gamma}}Te{sub m+2} materials. Because of their small size, the nanoinclusions are coherent with the matrix and therefore do not markedly degrade the electrical conductivity of the materials. As a result, very high figures of merit are achieved at high temperature for several compositions. For K{sub 0.95}Pb{sub 20}Sb{sub 1.2}Te{sub 22}, a maximum figure of merit ZT {approx} 1.6 was obtained around 750 K. This value is similar to that of n-type LAST-18 and is two times larger than that of the-state-of-the-art n-type PbTe.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); ONR
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 1009355
- Report Number(s):
- ANL/MSD/JA-69068; TRN: US201106%%545
- Journal Information:
- Chem. Mater., Vol. 22, Issue 3 ; 2010
- Country of Publication:
- United States
- Language:
- ENGLISH
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