A positron annihilation lifetime spectroscopic study of nanocrystals formation in a chalcogenide glass–ceramic

The positron annihilation lifetime spectroscopic technique was applied to study nanocrystals formation during controlled crystallization of a chalcogenide glass 51GeS2–9Sb2S3–40PbS, which was thermally treated at 330 °C for up to 15 h. The technique provided valuable information for in depth understanding of the nature of the material as well as the crystallization processes by showing systematic change of lifetime components (τ1, τ2, τ3) and intensities (I1, I2, I3) with thermal treatment time. Such change defines the time frame for nucleation and crystal growth processes; the nucleation process is dominating in the first 3 h, whereas after 3 h, the crystal growth becomes the main process. The values of lifetime components and their intensities reveal change of the size and amount of nano- and micro-defects with time and can be used to guide materials engineers for efficient composition designs and improvements of chalcogenide glass–ceramics.