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A computational fluid dynamics model of the glass fiber extrusion process is proposed and verified. The model describes the homogeneous non‐isothermal motion of a viscous glass melt and the surrounding air in an experimental setup, taking into account the interface between the media and the movement of the metal rod. The unclad Ge28Sb12Se60 glass fibers for sensor applications are fabricated by extrusion. The validation of the developed model is performed based on the experimental data, including pressure values, temperature field in extrusion setup, and extruded glass mass outflow. Based on the proposed model, the thermal and kinetic conditions for the flow of Ge28Sb12Se60 glass during extrusion are numerically studied. The presented model could be used as a tool for analyzing the hydrodynamic and thermal processes during fiber extrusion. [ABSTRACT FROM AUTHOR]

The adhesion strength of the solid phase boundary in the Ge20Se80 glass–substrate (quartz glass, stainless steel, tungsten carbide) systems was measured using the normal separation method in the temperature range of 270 – 360°C. The maximum work of adhesion of chalcogenide glass among the studied structural materials was observed for stainless steel with a non-nitrided surface. The wetting and adhesion of the Ge20Se80 glass melt to structural materials in the temperature range of 370 – 470°C were investigated. The maximum adhesion of the chalcogenide melt is observed for the surface of quartz glass, while the minimum is observed for the surface of nitrided stainless steel. [ABSTRACT FROM AUTHOR]

Using normal pull-off testing, we have studied adhesion contact strength in the GaxGe40–xS60–quartz glass system as a function of contact formation temperature, pull-off test temperature, and chalcogenide glass composition. The addition of 1 at % gallium to glass composition considerably reduces the adhesion strength. Further increasing the percentage of gallium, to 8 at %, causes only a slight drop in adhesion. The observed general relationships can be accounted for by partial glass crystallization on heating for adhesion contact formation and subsequent cooling to the pull-off test temperature. We have formulated recommendations concerning detachment of GaxGe40–xS60 glasses from the quartz reactor wall. [ABSTRACT FROM AUTHOR]

The temperature dependences of the charge-carrier concentration and lifetime of minority carriers in undoped and arsenic-doped p-type Hg1 - xCdxTe epitaxial layers with x ≈ 0.4 grown by the MOCVD-IMP (metalorganic chemical vapor deposition-interdiffusion multilayer process) method are studied. It is shown that the temperature dependences of the charge-carrier concentration can be described by a model assuming the presence of one acceptor and one donor level. The ionization energies of acceptors in the undoped and arsenic-doped materials are 14 and 3.6 meV, respectively. It is established that the dominant recombination mechanism in the undoped layers is Shockley-Read-Hall recombination, and after low-temperature equilibrium annealing in mercury vapors (230°C, 24 h), the dominant mechanism is radiative recombination. The fundamental limitation of the lifetime in the arsenic-doped material is caused by the Auger-7 process. Activation annealing (360°C, 2 h) of the doped layers makes it possible to attain the 100% activation of arsenic. [ABSTRACT FROM AUTHOR]