Formation of ordered nano-wire microstructures in thermoelectric Pb-Ag-Sb-Te
Journal
Acta Materialia
Journal Volume
60
Journal Issue
3
Start Page
1129
End Page
1138
ISSN
13596454
Date Issued
2012
Author(s)
Abstract
Regular arrays of nano-wire microstructures containing Ag 2Te rods with diameter <400 nm and inter-rod distance <1 μm are formed in a matrix of AgSbTe 2 + δ-Sb 2Te, which makes an ordered nano-wire composite thermoelectric material. This microstructure is formed during eutectic solidification processing. To understand and guide production of uniform bulk samples of this composite, the liquidus projection of quaternary Pb-Ag-Sb-Te system at 36.0 at.% Te isoplethal section is constructed experimentally, using quenched samples. A three-phase univariant reaction of the quaternary Pb-Ag-Sb-Te system, L → AgSbTe 2 + Ag 2Te + δ-Sb 2Te, is investigated, between a ternary-eutectic melt (Ag-40.0 at.% Sb-36.0 at.% Te) and a quaternary melt (Pb-22.0 at.% Ag-40.0 at.% Sb-36.0 at.% Te), at 496.1 °C and 503.9 °C, respectively. High-resolution transmission electron microscopy confirms that these three phases are simultaneously present at the nanometer scale. Furthermore, unidirectional solidification experiments of the ternary eutectic alloy using the Bridgman method are carried out to examine the alloy's solidification behavior. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Subjects
Bridgman technique
Eutectic solidification
Nanostructure
Solidification microstructure
Thermodynamics
Type
journal article