共查询到20条相似文献,搜索用时 93 毫秒
1.
V. V. Golubkov N. G. Tyurnina Z. G. Tyurnina V. L. Stolyarova 《Glass Physics and Chemistry》2009,35(5):455-462
The structure of single-phase glasses in the SrO-B2O3-SiO2 system has been studied by the small-and large-angle X-ray scattering technique. The glasses containing 35, 40, and 45 mol
% SrO upon equimolar replacement of B2O3 by SiO2 have been investigated. It has been demonstrated that the glasses do not contain chemical inhomogeneity regions. The inhomogeneity
of the glasses is determined only by thermal density fluctuations. The isothermal compressibility varies insignificantly upon
replacement of B2O3 by SiO2 and decreases with an increase in the SrO content. The glass structure is consistent with the model of ideal associated solutions. 相似文献
2.
The crystallization of strontium borate glasses containing 16.7–43.0 mol % SrO is investigated. New crystalline compounds of the hypothetical compositions 2SrO · 3B2O3 (metastable) and SrO · 5B2O3 (stable below 750°C), as well as the metastable diborate modification β-SrO · 2B2O3, are revealed, and their X-ray powder diffraction data are obtained. It is demonstrated that, with a deficit of strontium oxide, the 4SrO · 7B2O3 compound forms solid solutions. Strontium triborate SrO · 3B2O3, which was previously prepared only through the dehydration of crystal hydrates, is produced using crystallization of glasses. The thermal stability of this compound is studied. The influence of the dispersity on the stability of different crystalline phases is discussed. Variants of the phase diagram for the SrO · B2O3-B2O3 system in the case of monolithic and dispersed samples are proposed from analyzing the experimental results and the data available in the literature. 相似文献
3.
V. A. Sokolov T. Ya. Malysheva M. D. Gasparyan 《Refractories and Industrial Ceramics》2008,49(2):146-148
Details are given of the synthesis and testing of flux-cast refractory materials in the alumina-rich region of the Al2O3-MgO-B2O3 system; XRD and petrography indicate that the main structure-forming phases are corundum and magnesian spinel. In subordinate
amounts there are the boroaluminate 9Al2O3·2B2O3 and the previously unknown compound 4Al2O3·MgO·2B2O3, whose composition has been established by microprobe analysis. Corrosion tests showed that three-component systems containing
magnesium and boron oxides at levels of 5–10% do not increase the corrosion resistance of refractories in molten sodium-calcium-silicate
glass and electrovacuum borosilicate glass.
__________
Translated from Novye Ogneupory, No. 3, pp. 161–163, March, 2008. 相似文献
4.
S. V. Stolyar N. G. Tyurnina Z. G. Tyurnina L. A. Doronina 《Glass Physics and Chemistry》2008,34(4):509-511
The temperature dependences of the viscosity are investigated for three series of glass melts in the SrO-B2O3-SiO2 system with a constant strontium oxide content equal to 35, 40, or 45 mol % in the viscosity range from 1010 to 1013 P. 相似文献
5.
V. V. Golubkov V. L. Stolyarova Z. G. Tyurnina N. G. Tyurnina 《Glass Physics and Chemistry》2010,36(5):554-560
The structure of single-phase glasses in the BaO-B2O3-SiO2 system has been studied by the large- and small-angle X-ray scattering techniques. The glasses containing 40 mol % BaO upon equimolar replacement of B2O3 by SiO2 have been investigated. It has been demonstrated that the incorporation of barium ions into structural groupings fixes their position and provides ordering in the distribution of barium ions at interatomic distances up to at least 5 Å. The glasses under investigation are homogeneous, and their inhomogeneity is determined by thermal density fluctuations and fluctuations of the concentration of a part of barium ions distributed in a statistically random manner in the volume of the glass. The observed ordering in the distribution of barium ions is not reduced to the formation of local clusters with an increased concentration of barium ions but is most likely a characteristic feature of the bulk glass structure. The glass structure is consistent with the model of ideal associated solutions. 相似文献
6.
The linear thermal expansion coefficients below and above the glass transition range and the glass transition temperatures in the SrO-B2O3-SiO2 system are determined using a quartz dilatometer. 相似文献
7.
The density d at a temperature of 25°C is measured by the hydrostatic weighing method, the Vickers microhardness H V is determined, and the fluctuation free volume fraction f g is calculated for glasses in the SrO-B2O3-SiO2 system with a constant strontium oxide content in the range from 35 to 45 mol %. It is demonstrated that the quantities H V and f g decrease and the density d increases with an increase in the SrO content. 相似文献
8.
I. A. Zvereva A. M. Sankovich A. B. Missyul’ V. L. Ugolkov 《Glass Physics and Chemistry》2010,36(2):209-216
The processes of phase formation in the Nd2O3-TiO2-Na2CO3 system have been investigated in the temperature range 500–1100°C. The mechanism of the high-temperature solid-phase reaction
of formation of the complex oxide Na2Nd2Ti3O10 has been studied. It has been established that the Na2Nd2Ti3O10 compound is formed from the intermediate product Na0.5Nd0.5TiO3 with a perovskite structure in the temperature range 830–890°C and from the NaNdTiO4 oxide with a perovskite-like layered structure in the temperature range 960–1100°C. 相似文献
9.
S. S. Ordan’yan D. D. Nesmelov S. V. Vikhman 《Refractories and Industrial Ceramics》2009,50(5):391-393
Experiments and calculations have been applied to the structure of the triple eutectic system SiC–W2B5–LaB6(T
eu = 1900 ± 40°C), composition in mol.%: 10 LaB6, 44 SiC, 46 W2B5, error ±2–3%, which opens up prospects for making ceramic materials for various purposes. 相似文献
10.
Results are provided for a physicochemical study of processes that occur during synthesis of eutectic composition of the CaO–B2O3–SiO2 system in a solid phase, and the possibility of their activation by using starting calcium-containing components with different
chemical and thermal prehistory. It is established that independent of the form of starting components, in all cases there
is formation of a crystalline eutectic phase, and the sequence of physicochemical processes that occur is determined by the
reaction capacity of the calcium compound introduced. 相似文献
11.
R. P. Yavetskiy E. A. Vovk S. V. Parkhomenko V. F. Tkachenko I. G. Polyakova A. L. Prosvirnin 《Glass Physics and Chemistry》2009,35(4):389-396
The physicochemical features of the phase formation upon crystallization of monolithic glasses of the strontium diborate stoichiometric
composition are investigated. It is demonstrated that the first phase crystallizing on the surface of the SrO · 2B2O3 glass is the strontium borate Sr4B14O25, which plays the role of a precursor for the subsequent crystallization of the SrB4O7 borate. The temperature corresponding to the maximum crystal nucleation rate on the surface and the time of complete “operation”
of nuclei are determined using differential thermal analysis. The optical glass-ceramics prepared by the two-stage crystallization
are surface-crystallized glasses in which the filling density of the surface is approximately equal to 30% and the content
of the main phase SrB4O7 is as high as ∼ 70%. No second harmonic generation of neodymium laser radiation in the glass-ceramics is observed because
of both the absence of the preferred orientation of SrB4O7 nonlinear optical crystals and the small crystal sizes (considerably smaller than the coherence length of the SrB4O7 crystal) in the direction perpendicular to the glass surface. 相似文献
12.
The Sb2O3 doping lead-free glass in Bi2O3-B2O3-BaO ternary system were prepared in the composition of several different subsystem, and the glass powder was produced through
the process of water quenching. Glass transition temperatures (T
g
), glass soften temperatures(T
s
), the volume resistivity (ρ) in the temperature range of 80–200°C, and linear thermal coefficients of expansion in the temperatures
range of 25–300°C (α25–300) were measured for subsystems along with the different ratio of Bi2O3, B2O3 and BaO. For these subsystems, T
g
ranged from 458 to 481°C, and T
s
ranged from 490 to 512°C, both decreasing with the increasing of Bi2O3/B2O3 ratio, and increasing with the increasing of BaO/B2O3 ratio. The measured α25–300 ranged from 65.3 to 76.3 × 10−7 K−1, with values increasing with increasing Bi2O3/B2O3 and BaO/B2O3 ratio. The volume resistivity remains at a high standards, which may caused by it’s non-alkali composition, and it fluctuated
from 1013 to 1011 Ω cm with the temperature varied from 80–200°C. The structure of Bi2O3-B2O3-BaO ternary leadfree glass system was mearsured by FT-IR. The IR studies indicate that these glasses are made up of [BiO6], [BO3], and [BO4] basic structural units, and it appears that Ba2+ acts as a glass-modifier in this ternary system, but the Bi3+ has entered the glass network when it is in relative high content so as to change the α25–300, T
s
and T
g
. 相似文献
13.
The features of the volumetric nucleation of crystals in glass obtained by melting furnace slags with the additive of SiO2, chromium sesquioxide Cr2O3, are studied by the methods of differential thermal and Xray phase analysis and optical microscopy. Upon the introduction of Cr2O3 as the catalytic additive, two phases are sequentially formed in the glass: magnesiochromite (MgO · Cr2O3) and diopside (CaO · MgO · 2SiO2). The characteristics of homogeneous and heterogeneous crystallization are determined: the stationary nucleation rate, nonstationary nucleation time, crystal growth rate, and their temperature dependences are obtained. Practical recommendations on the use of the obtained glass are given. 相似文献
14.
L. A. Angolenko G. D. Semchenko E. E. Starolat S. A. Savina S. V. Tishchenko V. V. Povshuk 《Refractories and Industrial Ceramics》2010,51(4):274-278
Comparative characteristics are presented for the physicomechanical properties and oxidation resistance of refractory materials
of Al2O3–Si3N4–C composition based on an ACPB for the original materials (fired at 1400°C) and after impregnation with a sol-gel composition
and heat treatment at 800°C. Areduction in material porosity, increase in strength and reduction in carbon burn-off are due
to development of a glassy phase in the pore space and on graphite flakes due to SiO2formation with thermal destruction of the organosilicon substance. 相似文献
15.
R. G. Kuryaeva 《Glass Physics and Chemistry》2008,34(1):37-41
The pressure dependences of the refractive index for aluminosilicate glasses of the compositions 0.167CaO · 0.167Al2O3 · 0.666SiO2 and 0.157CaO · 0.177Al2O3 · 0.666SiO2 at pressures up to 6.0 GPa are determined using a polarizing interference microscope and an apparatus with diamond anvils. The compressibilities of the glasses are calculated from the measured refractive indices within the framework of the theory of photoelasticity. The structural-chemical parameters NBO/T (where NBO is the number of gram-ions of nonbridging oxygen atoms and T is the total number of gram-ions of network formers) are calculated for the glasses under investigation with allowance made for the formation of triclusters and highly coordinated aluminum. 相似文献
16.
The specific features of the chemical state of gold and indium oxide in Au-In2O3 (0.01–1.0 wt % Au) nanocomposites have been investigated by the methods of X-ray diffraction analysis, electron microscopy,
infrared and optical spectroscopy, electron paramagnetic resonance, and thermal analysis. Xerogels, powders, and films obtained
by the introduction of HAuCl4 into the indium hydroxide sol and thermal treatment at 50–700°C have been studied. The mutual influence of the components
on the size of the Au and In2O3 particles and the state of their surface has been established. It has been shown that the synthesis of Au-In2O3 by the sol-gel method leads to the formation of nanosized indium oxide particles with the high concentration of hydroxyl
groups on surfaces and favors the stabilization of gold in the form of nanoclusters and ion forms. 相似文献
17.
Structure and crystalline behavior of the ternary system ZnO-B2O3-P2O5 glasses were investigated by means of X-ray diffraction (XRD) and infrared Raman spectra. The research showed that number
of the planar [BO3] units increases with the increase of B2O3 content. When the B2O3 content is above ≥10 mol %, the relative content of planar [BO3] units increases rapidly and causes weakening of the glass structure and decrease in the chemical stability. In the crystallized
glasses the predominant crystal phase Zn2P2O7 decreases with the increase of B2O3 content, while the crystal phase BPO4 increases with it, which cause the declining of chemical stability and the decrease of thermal coefficients of expansion. 相似文献
18.
R. G. Kuryaeva 《Glass Physics and Chemistry》2011,37(3):243-251
The refractive index of potassium aluminosilicate glass of the KAlSi3O8 composition in the pressure range up to 6.0 GPa has been measured using a polarizing interference microscope and an apparatus
with diamond anvils. The changes in the relative density, which characterize the compressibility of the K2O · Al2O3 · 6SiO2 glass, have been estimated in the pressure range under investigation from the measured refractive indices within the framework
of the theory of photoelasticity. The results have been compared with the data previously obtained for the Na2O · Al2O3 · 6SiO2 glass. Although the molar contents of Al2O3 and M
2O (where M = K or Na) are identical in these glasses, the KAlSi3O8 glass exhibits a higher compressibility, which agrees with the lower degree of depolymerization of this glass as compared
to that observed in the NaAlSi3O8 glass. The pressure derivative of the bulk modulus K′
t
, which is calculated from the Birch-Murnaghan equation for the KAlSi3O8 glass (K′
t
= 7–9), is higher than that for the NaAlSi3O8 glass (K′
t
= 5.5–6.0). An increase in the pressure derivative of the bulk modulus K′
t
upon replacement of the Na+ cations by the K+ cations is explained by the inhibition of compression of the large K+ cations, which are located in cavities and have a considerably larger orbital radius than the Na+ cations. This manifests
itself in the fact that the curves describing the dependences of the change in the relative density (d − d0)/d (compressibility) on the pressure P for the KAlSi3O8 and NaAlSi3O8 glasses converge at pressures above 4.0 GPa. 相似文献
19.
Zeolite Mazzite (MAZ) analogue was synthesized directly using piperazine as a structure directing agent. The reactive gel
composition used was (5.0–7.0) piperazine:(6.0–7.0) Na2O:Al2O3:20.0SiO2:400H2O. Using this composition, the reaction time was shortened greatly to 4 days and the crystallization time was reduced as well.
The DTA data showed that piperazine, in as-synthesized zeolite omega decomposed easily. The decomposition of the piperazine
occurred at 400–480°C. NH3-TPD analysis proved that zeolite H-omega from piperazine had strong surface acidity with ammonia desorption temperature up
to 590°C. 相似文献
20.
The possibility of calculating the thermodynamic properties of binary glass-forming systems containing both modifier (Na2O) and glass-former (B2O3) oxides with the use of the vacancy variant of the generalized lattice theory of associated solutions is demonstrated for glasses and melts in the Na2O-SiO2 and B2O3-SiO2 systems. 相似文献