Crystallization process on amorphous GeTeSb samples near to eutectic point Ge15Te85

One of most important properties of some tellurium-based chalcogenide glasses is the optical and electrical switching between two states: the glass and the crystalline state. The understanding in these systems of the glass to crystal transition and its transformation kinetics is essential for their application in non-volatile memories. GeTeSb and GeTe amorphous samples of compositions close to the eutectic point Ge15Te85 were obtained by rapid solidification from the liquid state employing melt spinning technique. The glass forming ability of this system, for this cooling technique, is restricted to a small composition range nearby the binary eutectic. The crystallization kinetics of the samples was studied by means of differential scanning calorimetry (DSC) under both isothermal and continuous heating regimes. The quenched samples and the crystallization products have been characterized by X-ray diffraction with Cu(Kα) radiation. The crystallization temperature, activation energy, crystallization enthalpy and the dependence of these properties on concentration are reported. The crystallization study of Ge15Te85 glasses shows: a primary crystallization of Te superimposed with a secondary crystallization of GeTe. The addition of Sb (5 at.%) to the eutectic point Ge15Te85 modifies this behavior: the crystallization of Ge13Sb5Te82 glasses consists on the crystallization of Te and Ge2Sb2Te5. The crystallization of the ternary glasses was modeled.