SYMMETRY AND STRESSED - STRAINED STATE OF ZINC SELENIDE SINGLE CRYSTALS GROWN UNDER EXTREME CONDITIONS.

Vitaliy Komar, Valeriy Migal, Oleg Chugai

Institute for Single Crystals, National Academy of Sciences of Ukraine, 60 Lenin Ave., 310001 Kharkov, Ukraine
e-mail: komar@isc.kharkov.ua

Keywords: zinc selenide single crystal, induced symmetry, elastic oscillations, stressed-strained state.

It is shown that induced symmetry and stressed-strained state arising in zinc selenide single crystals under extreme conditions of melt crystallization are defined by the conformity of the direction of external factors and crystal symmetry axes. As a consequence, there appear anomalies of optical, dielectric and elastic properties which widen the functional possibilities of the crystals in question.

Considered are different symmetry aspects of stressed state in 43m class crystals, and the anomalies of crystal properties bound up with this state. The symmetry induced by stressed-strained state is found to give rise to new piezoelectric modules, as well as to anisot- ropy of dielectric and thermal parameters. The latter substantially depend on the electric state of the crystals. It is shown that the in- duced symmetry also defines the peculiarities of the spectrum of natu- ral elastic oscillations of the samples shaped as sphere or disk.