Investigation of the Er-Sb-Te system

Methods of physicochemical analysis, namely differential thermal analysis (DTA), high temperature differential thermal analysis (HTTA), X-ray phase analysis (XRD), microstructural analysis (MSA) and microhardness measurements are used to determine the nature of the physicochemical interaction in the Er-Sb-Te ternary system.. Phase diagrams of the following quasi-binary Er2Te3-Sb2Te3, ErTe-Sb2Te3, ErTe-SbTe, ErTe-Sb and non-quasi-binary Er-Sb2Te3, D (ErSb3Te5,5)-Te sections are presented for the first time. It has been established that at a component ratio of 1:1 in the Er2Te3-Sb2Te3 system, a new ternary phase with the composition ErSbTe3 is formed, which crystallizes in the hexagonal syngony with unit cell parameters: a=0.408; c=3.045 nm. In the system based on Sb2Te3, solid solutions are formed, the boundaries of which are up to 3 mol% Er2Te3 at room temperature, and at the eutectic temperature it reaches about 8 mol% Er2Te3. The ternary combination of ErSbTe3 with an α-solid solution forms a eutectic, the coordinates of which are 20 mol % Er2Te3 and 800 K. The liquidus of the ErTe-Sb2Te3 system consists of two branches of primary crystallization of an α-solid solution based on Sb2Te3 and an Er2Te3 compound. In the ErTe-Sb2Te3 section, a region of homogeneity is also formed based on Sb2Te3 up to 5 mol % ErTe. The system state diagram is of the simple eutectic type. Eutectic coordinates 25 mol% ErTe and 850K. In the ErSb – ErTe and Sb – ErTe systems, no new ternary phases and homogeneity regions have been found. Eutectic coordinates in the ErSb – ErTe system; 50mol % ErTe and 1200K, and in the second system (Sb – ErTe) a degenerate eutectic is observed (at 900K). The cut Sb2Te3-Er intersects three, and D-Te two subordinate triangles. In both systems, ternary eutectic and peritectic invariant reactions occur at different temperatures. A projection of the liquidus surface of the Er-Sb-Te ternary system is also constructed, which consists of fourteen fields of primary crystallization of phases, separated by 25 monovariant equilibrium curves. Monovariant curves intersect at 11 nonvariant points, five of which are eutectic and six are peritectic.