Irradiation-induced photodarkening in evaporated As30Se60Cu10 films is studied. The transmission spectra are shifted towards longer wavelengths after irradiation. Increasing the irradiation flux seems to have negligible effect on the total decrease in the spectral transmission of these films. The change in transmission is found to increase with increasing chalcogenide film thickness. A quantitative description of the photodarkening effect is given. The calculations show that the photodarkening effect depends only on the value of the absorption coefficient regardless of its spectral distribution. The study of the photodarkening kinetics indicates that the latent darkening centres are directly proportional to the chalcogenide film thickness. The optical behaviour of the heat treated films after irradiation is also studied. The results are discussed on the basis of rearrangement of the constituent atoms which takes place within a short-range order of the network. Translated Abstract: Bestrahlungsinduzierte Photoverdunkelung wird an aufgedampften As30Se60Cu10-Schichten untersucht. Die Transmissionsspektren sind nach Bestrahlung zu längeren Wellenlängen verschoben. Eine Erhöhung des Bestrahlungsflusses scheint nur einen vernachlässigbaren Einfluß auf die Gesamtzunahme der spektralen Durchlässigkeit dieser Schichten zu besitzen. Es wird gefunden, daß die Änderung der Transmission mit zunehmender Chalkogenidschichtdicke zunimmt. Eine quantitative Beschreibung des Photoverdunkelungseffekts wird angegeben. Die Rechnungen zeigen, daß der Photoverdunkelungseffekt nur vom Wert des Absorptionskoeffizienten abhängt und ist unabhängig von seiner spektralen Verteilung. Die Untersuchung der Photoverdunkelungskinetik zeigt, daß die latenten Verdunkelungszentren direkt proportional zur Chalkogenidschichtdicke sind. Das optische Verhalten der wärmebehandelten Schichten nach Bestrahlung wird ebenfalls untersucht. Die Ergebnisse werden auf der Grundlage einer Umordnung der Konstituentenatome diskutiert, die innerhalb der Nahordnung des Netzwerks auftritt

The thermoelectric power of bulk specimens of the system Bi1 − xTex (0.3 x 0.6 at.) was studied. The effects of Te content, temperature and time of annealing were considered. For most of the compositions considered, the activation of holes seemed predominant. The electron activations, as well as mixed activations, seemed dependent on Te content and the conditions of annealing. Compensation semiconductor behaviour could also be observed. However, both the value and polarity of the Seebeck coefficient seemed dependent on Te content, conditions of annealing and the temperature of measurement

Results of differential scanning calorimetry (DSC) at different heating rates on Se0.7Ge0.2Sb0.1 glass are reported and discussed. From the heating rate dependence of glass transition, crystallization onset and peak crystallization temperatures values for the glass transition activation energy, Et, and the crystallization activation energy, Ec, were evaluated. The results are consistent with surface and one-dimensional crystallization for this glass. The calculated values of Et and Ec are 92±6 and 134±6 kJ/mol, respectively. This work was partly supported by a Grant-in-Aid for Scientific Research from the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) and DAAD, Germany

Results of differential scanning calorimetry (DSC) at different heating rates on Se0.7Ge0.2Sb0.1 glass are reported and discussed. From the heating rate dependence of glass transition, crystallization onset and peak crystallization temperatures values for the glass transition activation energy, Et, and the crystallization activation energy, Ec, were evaluated. The results are consistent with surface and one-dimensional crystallization for this glass. The calculated values of Et and Ec are 92±6 and 134±6 kJ/mol, respectively. This work was partly supported by a Grant-in-Aid for Scientific Research from the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) and DAAD, Germany

Results of differential scanning calorimetry (DSC) under isothermal conditions on Se70Ge20Sb10 glass are reported and discussed. By using the Avrami equation the activation energy for crystal growth (EG) has been evaluated and the crystallization mechanism has been studied. The results indicate that the crystallization process is a one-dimensional growth. The calculated value of EG is 142.8 kJ mol-1 for Se70Ge20Sb10 chalcogenide glass

Results of differential scanning calorimetry (DSC) under isothermal conditions on Se70Ge20Sb10 glass are reported and discussed. By using the Avrami equation the activation energy for crystal growth (EG) has been evaluated and the crystallization mechanism has been studied. The results indicate that the crystallization process is a one-dimensional growth. The calculated value of EG is 142.8 kJ mol-1 for Se70Ge20Sb10 chalcogenide glass

Results of differential thermal analysis (DTA) under nonisothermal conditions on five chalcogenide glasses of the InxSe1 − x system (x = 0.05, 0.10, 0.15, 0.20 and 0.25 at.) are reported and discussed. The crystallization mechanism has been studied by using DTA, scanning electron microscopy (SEM) and X-ray diffraction. From the dependence of the glass transition temperature (Tg), the onset crystallization temperature (Tc) and the crystallization peak temperature (Tp) on the heating rate (α), the glass transition activation energy (Et) and the crystallization activation energy (Ec) were derived. The calculated Et for InxSe1 − x varied between 246 and 309 kJ/mol. The results indicate that bulk crystallization with two-dimensional growth occurs for these glasses. The average activation energy of crystallization for InxSe1 − x varied between 105 and 125 kJ/mol. In0.10Se0.90 chalcogenide glass showed a minimum value of Ec as well as (Tc - Tg), which represents the thermal stability of the glass, indicating that this composition has a tendency towards crystallization more than the other compositions