Pb-Sb-Te三元合金相图500℃等温截面的实验测定

摘要

为了获得在PbTe基热电材料中掺杂Sb后的相关系,文中对Pb-Sb-Te三元系500℃等温截面进行了实验测定及相关系的分析研究.采用XRD、SEM及能谱仪对合金样品进行了测试分析,研究结果表明:Pb-Sb-Te三元合金体系500℃等温截面由5个单相区、4个两相区和5个三相区组成.其中,5个三相区分别是PbTe+Sb+δ,PbTe+δ+SbTe,PbTe+Sb2 Te3+Te,PbTe+Pb+Sb和PbTe+Sb2 Te3+SbTe;在500℃时,Sb元素在PbTe相中的固溶度为2.03 at.%,Pb在Sb2 Te3相中的固溶度较高,达到7.17 at.%;此外,在500℃下Pb-Sb-Te三元合金系中并未出现文献报道的Pb2 Sb6 Te11三元相.原因可能是Pb2 Sb6 Te11是一种亚稳态相,其性质不稳定,只可稳定存在于855K(≈580℃)的这个温度点,而本研究测定的是Pb-Sb-Te三元系合金在500℃下的等温截面,与580℃有偏差,Pb2 Sb6 Te11可能已分解为PbTe和Sb2 Te3相,因此没有观察到Pb2 Sb6 Te11相的存在.%In order to obtain phase relationship of Sb doped PbTe based thermoelectric material. The isothermal section of the Pb-Sb-Te ternary system at 500℃ was determined and analysed. The alloy samples were investigated by X-ray diffraction analysis ( XRD ) , scanning electron microscope ( SEM) and energy-dispersive X-ray spectroscopy ( EDS ) techniques. The results show that the isothermal section of the Pb-Sb-Te system at 500℃ is composed of five single-phase regions, four two-phase regions and five three-phase regions. Among them, the five three-phase regions are PbTe+Sb+δ, PbTe+δ+SbTe, PbTe+Sb2 Te3+Te, PbTe+Pb+Sb and PbTe+Sb2 Te3+SbTe, respectively. The solubility of Sb in PbTe phase is 2. 03 at.% at 500 ℃, and the solubility of Pb in Sb2 Te3 is up to 7. 17 at.%. Moreover, the Pb2 Sb6 Te11 ternary compound wasn't observed in present work. The reason may be that Pb2 Sb6 Te11 is a kind of metastable phase, which is not stable and only exists at the temperature of the 855 K (580℃) . The experiment in this work was designed to determine the isothermal section of Pb-Sb-Te ternary system at 500℃. Compared with the situation at 580℃, Pb2 Sb6 Te11 may have broken down into PbTe and Sb2 Te3 at 500℃, so Pb2 Sb6 Te11 phase was not ob-served.