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Small crystals of novel halogen-borate, Ph2B5O9Br demonstrate nonlinear optical activity comparable with that of LiNbO3 and KTiOPO4. The crystals are characterized by second-order nonlinear coefficients as high as 3.0 ± 0.5 pm/V, phase-matchable for YAG:Nd laser and its second harmonic radiations. Polar properties of Ph2B5O9Br together with its good glass-forming ability and some peculiarities of glass crystallization make promising the development of nonlinear materials on its base as single crystals, nanostructured glasses, and glass-ceramics. [ABSTRACT FROM AUTHOR]

Polarized Raman spectra of lanthanum borogermanate (LBG) glasses of different compositions, as well as of LBG glasses obtained by the hot-extrusion technique, have been obtained. In addition, the crystallization behaviour of LBG glasses of different compositions has been studied by differential thermal analysis and X-ray diffraction. Both the Raman spectra profile and the crystallization behaviour depend on the lanthanum-boron ratio. Polarized Raman spectra of hot-extruded samples show differences from the unextruded samples. For the first time, structural changes in glasses under hot-extrusion treatment were observed by vibrational spectroscopy. [ABSTRACT FROM AUTHOR]

Crystallisation behaviour of glasses in the K2O-TiO2-P2O5 (KTP) has been studied by DTA, XRD, EM and SHG techniques to isolate composition ranges where bulk precipitation of ferroelectric phase KTiOPO4 occurs. It was found that bulk crystallisation of KTiOPO4 at temperatures slightly exceeding Tg is initiated by addition of SiO2. Controlled heat treatment leads to formation of optically non-linear KTiOPO4 nano-particles in KTP glasses (like amorphous nanostructuring in KNS glasses) in initial stages of phase separation and produces nanoscaled modulation of polarisability and SHG effect. The results are compared to the xK2O xNb2O5(1-2x)SiO2 (KNS) systems. [ABSTRACT FROM AUTHOR]