Results of the variable temperature XRD measurements for obtained Ag2Se powder are shown in Figure 1. It can be seen that the as-prepared Ag2Se samples clearly show the structural transition from the low temperature orthorhombic phase to the high-temperature cubic phase. The first one is the orthorhombic structure phase of -Ag2Se with JCPDS No. 06-0501, which appears in the range from room temperature up to 523K. Similarly, from 453K and up to 573K the cubic phase α-Ag2Se with JCPDS No. 76-0135 is observed, that is, the one corresponding to high temperature. The mixed orthorhombic and cubic phases exist in temperature ranges of 453−523 K. Besides, an additional small peak at 2θ=38.4º appears, which corresponds to the peak (1 1 1) of cubic Ag (JCPDS No. 01-1167-0992).