Abstract
Devitrification study of Ge15Te82Sb3 is compared to Ge14Te84.5Sb1.5 amorphous alloys using differential scanning calo-rimetry (DSC) and X-ray diffraction; we show tellurium effect in isothermal crystallization phenomena. The DSC traces of Ge15Te82Sb3 fixed at 413?C show the phase separation in the sample with increasing transition temperatures Tg followed by two crystallization temperatures Tc1 and Tc2. This sample is compared to Ge14Te84.5Sb1.5 which crystallized by two transition temperatures and two crystallization temperatures Tc1 and Tc2. By X. Rays diffraction, we show that this behaviour is due to the presence of two phases in the amorphous sample with composition vitreous change during heating sample, the most important first one corresponds to the tellurium crystallization in the hexagonal form with 1.8 eV activation energy. The second correspond essentially to the crystallization of Te+ GeTe phase with 2.1 eV activation energy.
Highlights
Phase-change recording chalcogenide alloys are designed to have at least two structural forms, amorphous and crystalline, which can coexist at room temperature
Devitrification study of Ge15Te82Sb3 is compared to Ge14Te84.5Sb1.5 amorphous alloys using differential scanning calorimetry (DSC) and X-ray diffraction; we show tellurium effect in isothermal crystallization phenomena
The DSC traces of Ge15Te82Sb3 fixed at 413 ̊C show the phase separation in the sample with increasing transition temperatures Tg followed by two crystallization temperatures Tc1 and Tc2
Summary
Phase-change recording chalcogenide alloys are designed to have at least two structural forms, amorphous and crystalline, which can coexist at room temperature. Several factors [1], such as heat treatment are found to cause stability or crystallization of the alloys. The first system exhibit two glass transition and two crystallization temperatures peaks. Crystallization process of the Ge15.5–x Te84.5Sbx system is compared with the Ge15–xTe82 Sbx ternary eutectic system. Amorphous-crystalline transformations resulting from heat treatment were examined using an X-ray technique which can detect crystals in a glassy matrix, especially if the crystals are of dimensions greater than typically 100 nm [5]
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