Journal of Physical Studies 2(1), 139–142 (1998) DOI: https://doi.org/10.30970/jps.02.139 THE PIEZOOPTIC RELAXATION IN CRYSTALS OF THREEGLICYN SELENATE

B. G. Mytsyk, N. M. Demyanyshyn
Lviv Center of the Institute of Space Investigations, Naukova Str., 5a, UA-290601, Lviv, Ukraine

The photoelastic relaxation in ferroelectric crystals of threeglicyn selenate are investigated. The thermal anomalies of relaxation amplitudes are studied. The relative relaxation amplitudes $β_{km}$ have a large anisotropy and lie in the value range from -5\% to +13\% at $T$=16$^\circ$C and from +16\% to +90\% at the phase transition region. The results depend on the geometry of the experiment. A specific behaviour have been found to be characteristic of the temperature dependence of the relative relaxation amplitude $β_{31}$. Its value is changed in the region near $T_c$ from 0\% to $\pm ınfty $\%. The photoelastic relaxations and their temperature behaviour is written on the basis of a piezocaloric mechanism. Corresponding calculations are performed.

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