Journal of Physical Studies 8(3), 252–263 (2004) DOI: https://doi.org/10.30970/jps.08.252 ANOMALIES OF THE PIEZO-OPTICAL EFFECT IN THE FERROELECTRICAL PHASE OF CRYSTALS B. H. Mytsyk Lviv Center of the Institute of Space Research, 5a Naukova St., Lviv, UA–79053, Ukraine

In the article, large number of works was analyzed, in which thermal anomalies of the piezoelectrical effect were discovered in crystals with structural phase transitions. It was proved that the main criteria of such anomalies in the ferroelectrical phase are values of the phase transition temperature displacement at the operation of mechanical stress, values of thermooptical coefficients and their temperature derivatives. The mechanism of anomalies of piezo-optical coefficients in ferroelectrics is spread to the ferroelectrics and crystals with a disproportionate phase, and also to other physical effects induced by mechanical stress: the piezo-electrical one, elastic deformation, piezo-gyration, change of the angle between optical axes, turns of the optical indicatrix. The author succeeded in formalizing the basis of temperature anomalies of the piezo-optical effect relaxation in ferroelectrics on the basis of the piezo-caloric mechanism. Corresponding calculations give the agreement with experimental data within limits of the error $\sim 10\%$, which is typical of piezo-optical experiments.

PACS number(s): 78.20.Hp

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