The Baric Changes of the Electron Polarisability of LiRbSO_4, LiKSO_4 and (NH_4)_2BeF_4 Crystals

摘要

The effect of uniaxial mechanical stresses on the spectral and temperature dependences of principal refractive indices n_i and birefringence DELTA n_i of LiRbSO_4, LiKSO_4 and (NH_4)_2BeF_4 crystals have been studied in the wide spectral (250-800 mn) and temperature (100-800 K) ranges. Displacements of the PT points under the uniaxial stress action as well as both an extensition or narrowing of the temperature intervals of the incommensurate phase have been revealed. The baric increacement of the n_i was observed.