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Information × Registration Number 0219U101977, 0117U006454 , R & D reports Title New effective polytypic acoustooptic materials based on chalcogenide crystals of the TlInS2 group. Optimization of acoustooptic interaction geometry popup.stage_title Head Vasylkiv Yurii V., Registration Date 05-12-2019 Organization Vlokh Institute of Physical Optics popup.description2  The temperature behavior of birefringence increasing and angle of optical indicatrix (OI) orientation in β-TlInS2 crystals belonging to the family of TlIn(S1-xSex)2 solid solutions was investigated in a wide temperature range including regions of structural phase transitions. For these crystals, it was found that below TC2≈197 K there are two regions with different phases corresponding to two different polytypes c = 16c * and c = c *. The study of linear thermal expansion in crystals of TlIn(S1-xSex) solid solutions was carried out. It was shown that the temperature dependences of the linear elongation for different concentrations of selenium contain anomalies in the temperature range 120-150 C and 180-230 C. The temperature dependences of the relative elongation of TlGaSe2 crystals in the temperature range 100–293 K were experimentally investigated. It was shown that the temperature dependences of the relative elongations and the coefficients of thermal expansion are characterized by a number of anomalies, which probably correspond to the structural phase transitions between different polytypes. The Raman light scattering spectra of TlIn(S0.95Se0.05)2 crystals were investigated. The temperature behavior of the parameters of the optical phonons active in Raman light scattering (half-width, intensity and frequency) of TlIn(S0.95Se0.05)2 crystals was studied. It was found that in the temperature range of phase transitions, TlIn(S0.95Se0.05)2 single crystals can be characterized by a sequence of phase transitions similar to TlInS2, but not by a Lifshitz type point on the (x, T) phase diagram at x = 0.05, as previously thought. Product Description popup.authors Vasylkiv Yurii V. Gomonnai Oleksandr O. Mys Oxana G. popup.nrat_date 2020-04-02 Close