Internal friction in chalcogenide glasses Ge-As-Se system in glass transition region

Abstract

Purpose. The purpose of this work is detecting and determine of mechanisms of relaxation transitions in chalcogenide glasses Ge-As-Se system based on research of temperature dependences of internal friction, shear modulus over a wide temperature range on infralow frequencies.

Methods. The temperature dependences of the internal friction and the shear modulus for glasses in the Ge–As–Se system at infralow frequencies of forced torsional vibrations were measured by torsional pendulum method.

Results. For all the glasses under investigation, the mechanical losses rapidly increase and, simultaneously, the shear modulus decreases in the range of the glass transition temperature T_g. With an increase in the strain frequency, these effects shift toward the high_temperature range, which indicate that the intensive relaxation process proceeds in this temperature range. The parameters U_α and τ₀ of this relaxation process were determined from the frequency shift in the hightemperature branch Q^–1(T).

Conclusions. An increase in the internal friction and the mechanical compliance of glasses in the Ge–As–Se system in the range of the glass transition temperature Tg is caused by the activation of the α relaxation process.  At Z =2.6, the activation energy of this process increases considerably as a result of the change in the kinetic structural unit responsible for the relaxation process under consideration. α relaxation process occurs as a result of the full defreezing of the mobility of glass structure in T_g region.