期刊
JOURNAL OF ALLOYS AND COMPOUNDS
卷 478, 期 1-2, 页码 75-82出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2008.11.054
关键词
Thermoelectric materials; Precipitation; Phase transitions; TEM
资金
- Sandia Corporation
- Lockheed-Martin Company
- United States Department of Energy
- National Nuclear Security Administration [DE-AC04-94AL85000]
- US Department of Energy
- Office of Basic Energy Sciences
- Division of Materials Sciences
The microstructure of AgSbTe2, prepared by solidification, is investigated using electron microscopy. During solidification and thermal treatment, the material separates into a two-phase mixture of a rocksalt phase, which is Ag22Sb28Te50, and silver telluride, Ag2Te. Ag2Te formation results either from eutectic solidification (large lamellar structures), or by solid-state precipitation (fine-scale particles). The crystal structure of the AgSbTe2 phase determined by electron diffraction is consistent with a rocksalt structure that has a disordered cation sublattice. A preferred crystallographic orientation relationship at the interface between the matrix and the low-temperature monoclinic Ag2Te phase is defined and discussed. This orientation relationship is observed for both second-phase morphologies. In both cases, the orientation relationship originates from a topotactic (cube-on-cube) alignment of the Te sublattices in the initially cubic Ag2Te and the matrix at elevated temperature. This Te sublattice alignment is retained as the Ag2Te undergoes a cubic-to-monoclinic transformation during cooling. This orientation relationship is observed for both second-phase morphologies. (C) 2008 Elsevier B.V. All rights reserved.
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