Phase diagrams of the RE （rare earth）-Ⅳ-Ⅵ systems are very important for the design of rare earth doped diluted magnetic semiconductors （DMSs）, but related information is very limited. In this work, the phase equilibria of the Er-Sn-Te system in whole compositional range at room temperature were investigated mainly by means of X-ray powder diffraction （XRD） and differential thermal analysis （DTA）. The existences of 9 binary compounds, i.e., SnTe, ErTe3, EraTe3, ErTe, ErsSn3, Er11Sn10, ErSn2, Er3Sn7 and Er2Sn5 were confirmed. The phase diagram consisted of 12 single-phase regions, 21 binary phase regions and 10 ternary phase re- gions. The maximum solid solubility of Er in SnTe was determined to be about 7.5 at.%, none of the other phases in this system re- vealed a remarkable homogeneity range at room temperature. No ternary compound was found in this work.
