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A method of scanning photodielectric spectroscopy of crystals has been suggested. It is based on the measurements of small increments of the real Δε′ and imaginary Δε″ parts of effective dielectric permittivity at a smooth variation of the photoexcitation wavelength λ. The spectral functions Δε′(λ) and Δε″(λ) are presented in a complex plane, that is, in parametric view, and their characteristic points are determined. Application of this method on Cd1−xZnxTe crystals showed a possibility of determining the energy position of the localized states generated in the forbidden zone by the intrinsic structure defects.

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The vertical Bridgman method is used to obtain crystals of Zn1, Mg Se solid solutions (0.03 x 0.55). The composition of the samples is determined by means of electron-probe microanalysis. The methods of optical microscopy and X-ray analysis are used to investigate the structure of the crystal and to determine their lattice perameters. Investigated are the microhardness and microbrittleness of the grown crystals, as well as their polarizational, optical, photoelectric and dielectric properties depending on Mg concentration. The obtained crystals are found to possess anisotropy of physical properties. The largest anisotropy of their mechanical, polarizational and optical properties is observed in the crystals containing 5-6 at.% of Mg. The samples with such a concentration of Mg are applicable as a base for making thermostable multifunctional IR optical elements which can operate within a wide spectral region.

Definite axial and radial temperature gradients created in the directed growth zone ofzinc selenide single crystals lead to the formation ofsubstructures. Such crystals may be usedfor manufacturing piezoresonators, special optical elements for measuring the power oftransmitted laser radiation and modulating the latter.Zinc selenide single crystals possessing a unique combination of optical, mechanical and thermal properties are widely used in power IR-optics. The application field ofthis compound may be essentially extended due to the use ofthe peculiarities of their piezoelectrical, piezooptical and electrooptical characteristics caused by induced symmetry arising in the process of ciystal growth. The present paper is devoted to the technological, designing and some other problems of the development of power meters and laser radiation modulators based on ZnSe single crystals.The said material is characterized by rather weak piezoelectrical effect (d14=l. l 1012 CIN). Moreover, it often contains randomly distributed structure defects which deteriorate the properties of piezoresonators manufactured from it. At the same time, as shown by the results reported both in [1, 2J and in the papers of other investigators, it is by changing the density of structure defects that the electrophysical and thermal characteristics of the crystals may be controlled. In particular, the creation of definite axial and radial gradients in the zone of directed growth promotes the fonnation of substructures. Determined are the conditions for the growth of cellular, rod-like and laminated substructures. The formation of a rodlike substructure in zinc selenide single crystals is considered in [3]. As we have found, the effect of substructures on the crystal properties is mainly defined by induced symmetry. According to the Curie principle, the superposition of crystal symmetries and external factors preserves the common elements of the former, i.e. leads to the appearance of induced (lowered) symmetry. Under unchanged conditions the symmetry of the growing crystal is evidently effected by the growth axis orientation. The conoscopic patterns of the crystals containing substructures are similar to those of uniaXial and biaxial crystals. Revealed in some cases are weak dichroism and optical activity testifying to the presence of the deformation-induced transition 43m -42m. These features are not characteristic of cubic ZnSe crystals and may be attributed to the induced symmetry of the investigated samples. The amsotropy of dielectric permeability, thermal conductivity and thermal expansion coefficients defined by the crystal growth axis is another manifestation ofthe induced symmetry.It is due to the induced symmetry and small loses by internal friction that the investigated material excels conventional ZnSe in piezoelecrical and acoustic properties. The spectra of piezoelectrical resonances excited in the laser windows containing a substructure consist of strong widely separated resonances. In most cases these resonances are characterized b...