Nature of the cubic to rhombohedral structural transformation in (AgSbTe[subscript 2])[subscript 15](GeTe)[subscript 85] thermoelectric material
- Ames
The existence of a large thermoelectric figure of merit in (AgSbTe{sub 2}){sub 15}(GeTe){sub 85} has been known for many years. However, the nature of the crystallographic transformation in these materials from a high-temperature cubic to a low-temperature rhombohedral polymorph and its effect on electrical transport has not been clearly established. Transmission electron microscopy studies were performed that show extensive twinning in the low-temperature structure, resulting from lattice strain during the dilation along the (111) crystallographic direction. Analysis of differential scanning calorimetric studies indicates that the transformation is of second order, so that the high-temperature cubic phase is nonquenchable. High-temperature x-ray diffraction was performed to establish the transformation temperature, which was found to be complete upon heating at a temperature of 510 K. Results of electrical conductivity measurements as a function of temperature on as-cast samples are discussed in terms of the observed twinning.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1007679
- Journal Information:
- J. Appl. Phys., Vol. 101, Issue (5) ; 05, 2007; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- ENGLISH
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