The effect of Se a†" Te substitution on crystallisation micro-mechanisms evincing in GeTe4 glass

Isothermal and non-isothermal crystallisation behaviour of the GeTe3.9Se0.1 chalcogenide glass was studied dependent on particle size and compared to the similar DSC study performed for the pure GeTe4 material. The effect of the Se a dagger" Te substitution led to a decrease in the crystallisation process complexity in the case of powdered materials-the addition of Se led to domination of the slower nucleation-growth crystallisation mechanism over the fast autocatalytic growth from mechanically induced defects. The nature of the crystallisation mechanisms was confirmed by infrared microscopy and XRD. The addition of selenium into the GeTe4 matrix caused an enlargement of the identified crystallites; this, together with the overall deceleration of the crystallisation processes, indicates the suppression of nucleation processes. The presence of Se also greatly enhanced domination of the CNT-based three-dimensional growth of volume-located crystallites. The obtained findings provide a very good explanation for the markedly increased thermal stability of Se-doped Ge-Te infrared glasses.