Temperature operated infrared nonlinear optical materials based on Tl4HgI6

• Published in: Journal of materials science. Materials in electronics 2013-04, Vol.24 (4), p.1187-1193
• Main Authors: Piasecki, M., Lakshminarayana, G., Fedorchuk, A. O., Kushnir, O. S., Franiv, V. A., Franiv, A. V., Myronchuk, G., Plucinski, K. J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: structure, mechanical and thermal properties; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials; Materials Science; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical properties of nanoscale materials; Metals. Metallurgy; Optical and Electronic Materials; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-012-0903-6

In this work, we report on the synthesis and nonlinear optical features of novel temperature operated materials based on Tl 4 HgI 6 single crystals. Nonlinear optical, differential scanning calorimetry (DSC) and mechanical properties of the titled crystals are studied within the temperature range 300–500 K. We have established that Tl 4 HgI 6 single crystal show both positive and negative value of linear expansion temperature coefficient. The temperature region of rapid reduction coefficient for linear expansion is very small (only 2°–5°), which corresponds to occurrence of structural transformation for the Tl 4 HgI 6 single crystal. Comparison between the temperature dependence of the photo-induced optical second harmonic generation for the fundamental 5.5 μm wavelength is performed. We present an explanation for structural phase transition of the crystal Tl 4 HgI 6 considering temperature changes of crystal lattice parameters and describing the transition from centrosymmetric phase P 4/ mnc , at ambient temperature to non-centrosymmetric P 4 nc at T > 458 K. The photo induced changes indicate a possibility of occurrence of intermediate non-centrosymmetry phase. Particular analysis is devoted to correlate with the temperature dependence of the DSC within the same temperature range. Physical mechanisms responsible for the observation of the dependences are given and they are based on the condensation of the soft phonon modes which are closely related with the anharmonic electron–phonon interactions responsible for the effects.