Solubility and formation of ternary Widmanstätten precipitates in PbTe in the pseudo-binary PbTe–Bi2Te3 system
Solubility and formation of ternary Widmanstätten precipitates in PbTe in the pseudo-binary PbTe–Bi2Te3 system
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DOI：
10.1007/s10853-011-5301-6
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发表时间：
2011-02
影响因子：
4.5
通讯作者：
T. Ikeda;M. Toussaint;K. Bergum;Shiho Iwanaga;G. Jeffrey Snyder
中科院分区：
文献类型：
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作者：
T. Ikeda;M. Toussaint;K. Bergum;Shiho Iwanaga;G. Jeffrey Snyder
采用Bridgman法对Pb14Bi28.8Te57.2合金进行了定向凝固实验，发现在PbTe-Bi 2 Te 3系中形成了三元化合物的魏氏沉淀，其结构很可能为PbBi 2 Te 4.沉淀物的形成是由于随着温度的降低，铋在PbTe相中的溶解度降低所致。从单向凝固样品的成分变化和扩散偶分析了PbTe-Bi_2 Te_3相图中的富PbTe部分。这证明溶解度随温度降低而降低：15.6 ± 0.9（583 °C）至（450 °C）at.%双性恋用电子背散射衍射技术研究了基体和沉淀物之间的取向关系，沉淀物在PbTe的{111}惯习面上发生，取向关系为（0001）沉淀物//{111} PbTe和<110>沉淀物//<110>PbTe。用扫描塞贝克探针法测得的具有魏氏沉淀的PbTe的热电性能为-46 ± 2 μVK−1。
A unidirectional solidification experiment by Bridgman method has been performed for the Pb14Bi28.8Te57.2composition, which lies on the pseudo-binary PbTe–Bi2Te3system, resulting in the formation of Widmanstätten precipitates of a ternary compound, most likely with the structure of PbBi2Te4in the PbTe matrix. The formation of the precipitates is caused by the decrease of bismuth solubility in the PbTe phase with decreasing temperature. The PbTe-rich part of the PbTe–Bi2Te3phase diagram was investigated from the compositional variations in the unidirectionally solidified sample and the diffusion couples. This proved that the solubility decreases with decreasing temperature: 15.6 ± 0.9 (583 °C) to(450 °C) at.% Bi. The orientation relationship between the matrix and precipitates has been examined by electron backscatter diffraction technique; precipitation occurs on {111} habit planes in PbTe with orientation relationship (0001)precipitate//{111}PbTeand <110>precipitate//<110>PbTe. The thermoelectric properties in PbTe with Widmanstätten precipitates as examined by the scanning Seebeck probe method is –46 ± 2 μVK−1.