共查询到5条相似文献,搜索用时 0 毫秒
1.
Artem Malakho Marc Dussauze Bogdan Lazoryak Frederic Adamietz 《Journal of solid state chemistry》2005,178(6):1888-1897
Crystallization of glasses with compositions (1−x)(0.95 NaPO3+0.05 Na2B4O7)+xNb2O5, x=0.4, 0.43, 0.45, 0.48 was investigated by differential scanning calorimetry and X-ray powder diffraction. Crystallization of two phases was observed in the glasses with x=0.43-0.48. First phase is a sodium niobate with the structure of tetragonal tungsten bronze () and second phase is Na4Nb8P4O32 (). The crystallization of sodium niobate is correlated with increasing of nonlinear optical efficiency reported for thermally poled glasses with x>0.4. The results of Raman spectroscopy show the formation of three-dimensional (3D) niobium oxide framework in the glasses with increase of niobium concentration. This framework is supposed to have tetragonal tungsten bronze structure and to be responsible for nonlinear optical properties of the glass. Second harmonic generation signals of as prepared and crystallized glass after thermal poling are compared. The nucleation and crystallization do not improve the NLO properties of the glasses under study. 相似文献
2.
Lujian Chen Xuefeng Jin Yuanjing Cui Junkuo Gao Guodong Qian Minquan Wang 《Journal of Sol-Gel Science and Technology》2007,43(3):329-335
Organic–inorganic hybrid films containing nonlinear optical (NLO) active chromophores were prepared through the polyaddition
of methacrylate and hydrolytic polycondensation of sila-functional alkoxy groups of 3-(trimethoxysilyl)propyl methacrylate
(TSPM) which is capable of forming carbon–carbon and siloxane chains, respectively. The NLO-active chromophores are designed
and synthesized to be covalently grafted to the carbon–carbon or the siloxane chains. The comparative study of the two different
incorporation methods reveals that the poled hybrid film with NLO-active chromophores bonded to siloxane chains would possess
a more stable dipolar orientation. 相似文献
3.
Krishnakumar V Sivakumar S Nagalakshmi R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):119-124
Bisglycinehydrogenchloride (BGHC) an intriguing material for frequency conversion has been grown by slow evaporation solution growth technique at room temperature. Their structural, optical and physicochemical properties were characterized by X-ray powder diffraction, FTIR, Raman and UV-vis spectra. The title crystal has found to crystallize into noncentrosymmetric orthorhombic P2(1)2(1)2(1) space group. The material has a wide transparency in the entire visible region. It is found that the cutoff wavelength lies in the UV region. The mechanical response of the crystal has been studied using Vickers microhardness technique. The Kurtz powder second harmonic generation test shows that the compound is a prospective crystalline material for second order nonlinear optical application. 相似文献
4.
Balakrishna Kolli Sarada P. Mishra Akshaya K. Palai Tapan Kanai M. P. Joshi S. Raj Mohan T. S. Dhami L. M. Kukreja A. B. Samui 《Journal of polymer science. Part A, Polymer chemistry》2013,51(4):836-843
A series of dicyanomethylene‐substituted polymers having Y‐type molecular architecture were synthesized by Knoevenagel condensation reaction. The polymers were found to be soluble in organic solvents like tetrahydrofuran and chloroform. From gel permeation chromatography, the molecular weights of the polymers were found to be in the range of 15,300–33,800 g/mol. Thermal analysis showed that the polymers were stable up to 350 °C with glass transition temperature (Tg) in the range of 129–212 °C. These polymers were found to form good optical quality films. The order parameter was calculated to be in the range of 0.01–0.48. Atomic force microscopy indicated prominent morphology changes due to alignment of dipoles after poling. By using Nd:YAG laser of 1064 nm, angular dependence and temperature dependence of second‐harmonic generation intensity were investigated. The geometry optimization, shape of polymers, and restricted torsion angle between acceptor and donor substituents (push–pull system) were calculated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
5.
Advances in production are leading to increasing use of polymeric thin films in applications such as automotive bearings. Two approaches have been developed to study the thermophysical properties of these thin films: The first technique based on Flash theory uses a scanning thermal microscopy (SThM) tip in temperature contrast mode to measure thermal diffusivity over a nano-scale area. The SThM tip is in contact with the upper surface of the film to detect a heat pulse delivered by a microelectromechanical heater platform from the lower surface. The second technique is a conductivity contrast mode SThM based approach for measuring the size and distribution of thermally conducting particles in thin film polymeric coatings. Topographical and thermal conductivity data are combined to produce a “correlation analysis value” 3D particle map of the coating. Good practice and a case study are highlighted. 相似文献