Thermal, Structural, and Dielectric Properties of Cu‐Doped Ge‐S Glasses

Glasses of GeS 1.5 +y at.% Cu and GeS 1.375 +z at.% Cu were analyzed by DTA. For concentrations y ≊2.5 and z ≊4, new exothermic transformations and an initial small endothermic effect appear. All these transformations occur below the glass transition temperature of the original Ge:S glass, Analysis by X‐ray and electron diffraction showed that this devitrification process is connected with crystallization of a Cu 2 GeS 3 phase. Electron transmission microscopy showed that this crystalline phase is dispersed in a glassy matrix as disconnected aggregates with irregular symmetry. Near the maximum copper concentration y ≊5, z ≊6) at the boundary of the glass‐forming region, there is one additional exothermic transformation in the system GeS 1.5 +y at.% Cu and two in the system GeS 1.375 +z at.% Cu, one of them corresponding to crystallization of the Cu 3 GeS 4 phase. X‐ray diffraction patterns of the crystalline phases are shown. The spectrum of ionic thermocurrents in such glassyceramic material shows a new peak at 120 K which is probably related to interfacial polarization associated with the crystalline phase‐glassy matrix boundary.