Petchenko G. Relaxation and dynamic effects in acoustic crystals in weak energy fields

The thesis deals with the problem of phonon-dislocation interaction, the interaction of dislocations with the points of pinning, radiation stoppers and "forest" dislocations in ionic crystals. Dynamic and structural characteristics of crystals have been studied within methods of physical acoustics. The independence of the damping constant from the dislocation density for different temperatures in range 77 - 300 K and different X-ray doses has been proved. The methodology of determination of the absolute value of damping constant and its temperature trend by Debye temperature of the crystal has been offered. The nature of radiation centers (F - centers) and point stoppers (tetragonal defects) in crystals and the dynamics of their interaction with dislocations has been studied within the absorption method and thermal-activation analysis. The qualitative and quantitative correspondence of results of dynamic and structural characteristics in the field of low frequencies (study of frequency dependences of ultrasound velocity dispersion) and high frequencies (study of frequency dependences of dislocation ultrasound wave absorption) has been analyzed.