为了获得在Pb Te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Pb Te+Sb+δ,Pb Te+δ+Sb Te,Pb Te+Sb2Te3+Te,Pb Te+Pb+Sb和Pb Te+Sb2Te3+Sb Te;在500℃时,Sb元素在Pb Te相中的固溶度为2.03 at.%,Pb在Sb2Te3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Pb2Sb6Te11三元相。原因可能是Pb2Sb6Te11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,Pb2Sb6Te11可能已分解为Pb Te和Sb2Te3相,因此没有观察到Pb2Sb6Te11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+Sb2Te3+Te, PbTe+Pb+Sb and PbTe+Sb2Te3+SbTe, respectively. The solubility of Sb in PbTe phase is 2.03 at. % at 500 ℃, and the solubility of Pb in Sb2Te3 is up to 7.17 at. %. Moreover, the Pb2Sb6Tell ternary compound wasn't observed in present work. The reason may be that Pb2Sb6Tenis 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 ℃, Pb2Sb6Te11 may have broken down into PbTe and Sb2Te3at 500 ℃, so Pb2Sb6Ten phase was not observed.