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Hits: 9100
The spectral-luminescent properties of potassium-aluminophosphate glass containing Eu
3+ ions during thermally stimulated formation of gold nanoparticles in its volume have been investigated. It is shown that the formation of gold clusters (pre-plasmonic particles) leads to an increase in the luminescence intensity of rare-earth ions, while the formation of gold nanoparticles with localized plasmon resonance leads to a decrease in the luminescence intensity.
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Hits: 9385
The possibility of the formation of birefringent microregions in sodium borosilicate glass with the composition 68 SiO
2 , 27 B
2 O
3 , 4 Na
is demonstrated. 2 O, 1 Al
2 O
3 (molar content, & # 37;), the birefringence of which is associated with the formation of nanolattices, and its slow axis is oriented perpendicular to the plane polarization of the recording laser beam. The dependences of the phase shift in the light passing through these microregions on the number and energy of the laser pulses that formed them were determined. It was shown by confocal Raman spectroscopy that the content of sodium cations decreases in the formed microregions.
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Hits: 9594
The possibility of glass formation in the four-component system La
2 O
3 -Al
2 O
3 -B
2 < / sub> O 3 -SiO 2 with a molar content of La 2 O 3 27 & # 37 ;. The ratios of the components at which glasses are most stable with respect to amorphous phase separation and crystallization have been determined. Composition area limited by the limiting values ??of the molar content of the components: 7 - 30 SiO 2 , 8 - 25 Al 2 O 3 , 32 - 50 B < sub> 2 O
3 , allows to obtain glasses with refractive index nD up to 1.74, dispersion coefficient & Nu;
D up to 57 and density no more than 4, 15 g / cm
3 . The manufacturability of melting and production of these glasses creates the prerequisites for creating materials with various combinations of optical constants by modifying the matrix with a wide range of doping components.
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Hits: 9524
The chemical activity to cement alkalis (ASR interaction) of porous fillers - foam ceramics and geopenositals (analogs of foam glass and foam glass) in an alkaline medium simulating the liquid phase of hardening cement - has been investigated. It was found that devitrification of the glass melt in the process of thermally activated pore formation increases the ASR stability of ceramic foam fillers provided that the crystals are uniformly distributed over the pore wall thickness. It is shown that in an alkaline medium, the active surface of ceramic foam fillers is encapsulated by crystalline Ca-, Na-aluminosilicates and further ASR interaction stops.
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Hits: 9833
The effect of SnO on the physicochemical properties of low-melting glasses of the Li
2 O-SnO-P
2 O
5 (LSP) system intended for use in compositions for vacuum-tight low-temperature joining of various materials. Low T
g values ??contributed to the high flow of LSP glass powders at temperatures below 450 ° C (typical for gluing electronic products). The weight loss during boiling of LSP glasses varied over a wide range (0.19 - 4.55 & # 37;), and glasses characterized by weight loss below & # 8776; 3 & # 37 ;, are superior in chemical resistance to lead-borate glasses widely used in soldering compositions. By optimizing the ratio of the alkali content, it was possible to increase & # 447;
v LSP glasses to values ??characteristic of lead borate glasses
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Hits: 10066
The kinetics of structural relaxation of oxide systems containing complexing elements - boron and silicon - has been studied by potentiometric method. The influence of the nature of the oxide electrolyte, its composition and quenching temperature on the kinetic parameters of the anionic polymerization process has been revealed. Modeling of relaxation processes in liquid borosilicates is carried out. Two kinetic schemes of structural relaxation are considered, taking into account the slowness of the depolymerization of silicon-oxygen complexes and the change in the coordination of boron. The influence of various physicochemical factors on the rate of relaxation processes and the time to reach equilibrium is analyzed.
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Hits: 10067
The results of studies on the formation of the crystalline phase in the foam glass matrix, as well as the effect that it has on the operational properties of the material (compressive strength, density, etc.) are presented. The features of the technological process of the synthesis of foam glass are shown taking into account directional crystallization. It was found that to increase the strength of the foam glass, an amorphous-crystalline framework is required (the content of the crystalline phase is up to 20 & # 37;), in which the reinforcing role will be played by crystalline inclusions of a certain size (35 - 50 nm)
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Hits: 10165
A physicochemical analysis of technologies for creating quartz grains and smelting glasses from them has been carried out. Experimental smelting of glass from grits has been carried out. Melting conditions ensured the formation of a fine-grained inhomogeneity with a volume mesh of boundaries in a glass ingot decorated with impurities. The results of optical, electron microscopic and mass spectrometric studies confirm the new hypothesis of the appearance of fine-grained inhomogeneity in silica glass. The research results can be taken into account when smelting ultra-pure quartz glass with high quality factor for high-tech industries.
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Hits: 10313
Mathematical models of the dynamics of mechanical stress fields in glassware of complex configuration of cylindrical-conical and prismatic-cylindrical type have been developed. On the basis of the obtained models of the dynamics of temperature fields on the basis of the relaxation theory of glass transition, finite-difference equations were obtained, which made it possible to carry out computer modeling of the process of changing the stress state in glass during its annealing. The results of a machine experiment on models of the dynamics of the field of mechanical stresses in glassware are presented.
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Hits: 10329
The technological properties of basalt melts and glasses obtained on the basis of basalt - colemanite composites have been investigated. The possibility of decreasing the temperature of continuous fiber production when using boron-containing compositions is established, which is due to a decrease in viscosity, liquidus temperature and crystallization ability of the melt.
