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1.
MARIA ISABEL NIETO ALICIA DURAN JOSE MARIA FERNANDEZ NAVARRO JOSE LUIS OTEO MAZO 《Journal of the American Ceramic Society》1984,67(4):242-244
Infrared spectra of glasses of the system R2 O-B2 O3 -SiO2 were investigated. The extinction coefficients of the hydroxyl absorption band ("free OH") were calculated by a method proposed for alkali borate glasses. The results confirmed the applicability of this method to homogeneous and phase-separated alkali borosilicate glasses. The variation of the hydroxyl absorption band position was interpreted according to the structural characteristics of the studied glasses. 相似文献
2.
Quadrupole interactions of 11 B and 27 Al in SiO2 -B2 O3 -Al2 O3 -R2 O glass systems were investigated to determine the structure of these glasses, which should be amenable to chemical strengthening. The ratio of BO4 units to BO3 units approached unity as the R2 O/Al2 O3 ratio for compounds having fixed B2 O3 contents approached unity. Nuclear quadrupole coupling constants ( e2 Qq/h =2.73 to 2.93 MHz) were measured for the NMR spectra of 11 B triangles. The line shapes of 27 Al spectra varied with chemical composition, but a few glasses exhibited 27 Al line shapes similar to those of the AlO4 triclusters in SiO2 -Al2 O3 -Na2 O glasses. Compositional trends in the formation of BO4 and AlO4 were deduced from the NMR spectra. 相似文献
3.
Günther H. Frischat Wolfgang Krause Horst Hübenthal 《Journal of the American Ceramic Society》1984,67(1):10-C-
Up to 3.3 wt% nitrogen can be incorporated into Na2 O-B2 O3 glass melts. The melting procedure is described, and structure models are given. In contrast to N-containing silicate glasses, the borate glasses were transparent; however, micrographs of their fracture surfaces showed some crystallinity. Properties were determined as a function of the N and Na2 O contents of the glasses. Compared with N-containing silicate glasses, the properties of borate glasses are much less changed by the nitrogen introduced. 相似文献
4.
KEIJI KOBAYASHI 《Journal of the American Ceramic Society》1979,62(9-10):440-442
Interdiffusion of silver ions in SiO2 -B2 O3 -AI2 O3 -R2 O glasses where R=Na or K was investigated, using optical transmission, ESR, and wet chemical methods to determine concentration and the chemical state of silver, and NMR spectra as a probe of the glass structure. The concentration of silver introduced by ion exchange increased monotonically, as the line widths of27 AI NMR spectra decreased. The sharp and narrow features of 27 Al line shapes were broadened and the amount of colloidal silver produced by ion exchange decreased, as R2 O/B2 O3 approached unity with fixed AI2 O3 . The BO4 to BO3 ratio approached unity and the quadrupole coupling constant of BO3 units varied from 2.70 to 2.96 MHZ , as R2 O/AI2 O3 , approached unity for fixed B2 O3 . These diverse data suggest a relation between silver diffusion and glass structure, although the phenomena of phase separation and the mixed-alkali effect could also influence silver-colloid formation in the glasses studied. 相似文献
5.
Clear glasses form in the system Ag2 O-B2 O3 up to about 35 mol% (65 wt%) Ag2 O. Infrared absorption, thermal expansion, and density data indicated an analogy to the Na2 O-B2 O3 system. Pentaborate-triborate group pairs appear to be formed on addition of Ag2 O to B2 O3 up to 20 mol% Ag2 O and diborate groups from 20 to 33 mol% Ag2 O. This interpretation is supported by the comparison of the infrared absorption spectra of quenched and crystallized glasses. One crystallization product, Ag2 O-4B2 O3 , was identified previously. A new compound starts to appear at 28 mol% Ag2 O. The theory that silver is generally present as a network modifier like sodium was substantiated by the comparison of the molar volume of sodium and silver borate glasses. Above 27 mol% Ag2 O some atomic silver is assumed to be present; below 15 mol%, exploratory studies indicate a two-phase structure within an immiscibility gap. A low-temperature internal friction peak in the glasses up to 28 mol% Ag2 O corresponds to the alkali peak in other glasses; a high temperature peak appearing in the 34 mol% Ag2 O glass is associated with the appearance of nonbridging oxygen in the system. 相似文献
6.
Daniel Caurant Odile Majérus Edward Fadel Marion Lenoir Christel Gervais Olivier Pinet 《Journal of the American Ceramic Society》2007,90(3):774-783
Crystallization of the poorly durable Na2 MoO4 phase able to incorporate radioactive cesium must be avoided in SiO2 –Al2 O3 –B2 O3 –Na2 O–CaO glasses developed for the immobilization of Mo-rich nuclear wastes. Increasing amounts of B2 O3 and MoO3 were added to a SiO2 –Na2 O–CaO glass, and crystallization tendency was studied. Na2 MoO4 crystallization tendency decreased with the increase of B2 O3 concentration whereas the tendency of CaMoO4 to crystallize increased due to preferential charge compensation of BO4 − entities by Na+ ions. 29 Si MAS NMR showed that molybdenum acts as a reticulating agent in glass structure. Trivalent actinides surrogate (Nd3+ ) were shown to enter into CaMoO4 crystals formed in glasses. 相似文献
7.
Kentaro Terashima Suguru Tamura Sea-Hoon Kim Toshinobu Yoko 《Journal of the American Ceramic Society》1997,80(11):2903-2909
The third–order nonlinear optical susceptibility, χ(3) , of lanthanide (lanthanum, praseodymium, neodymium, and samarium) borate glasses has been measured by the third harmonic generation method. The structure of the present glass system has been studied by infrared and Raman spectroscopic methods. The network structures of the present Ln2 O3 –B2 O3 glasses have been confirmed to be basically similar to each other. Praseodymium, neodymium, and samarium borate glasses exhibit χ(3) values that are larger than lanthanum borate glasses, because of the optical resonance effect, in accordance with the f – f transition. Especially, the χ(3) value for 30Pr2 O3 ·70B2 O3 glass is 1.8 × 10−12 esu, which is a factor of ∼60 larger than that of SiO2 glass. This striking enhancement of χ(3) is mainly attributed to the large transition moment to the first excitation state. 相似文献
8.
Debao Zhang Baoyu Chen Zhuping Liu Shunguang Li Lili Hu 《Journal of the American Ceramic Society》2004,87(12):2228-2231
Er3+ -doped sodium lanthanum aluminosilicate glasses with compositions of (90− x )(0.7SiO2 ·0.3Al2 O3 )· x Na2 O·8.2La2 O3 · 0.6Er2 O3 ·0.2Yb2 O3 ·1Sb2 O3 (in mol%) ( x = 12, 20, 24, 40, 60 mol%) were prepared and their spectroscopic properties were investigated. Judd–Ofelt analysis was used to calculate spectroscopic properties of all glasses. The Judd–Ofelt intensity parameter Ω t ( t = 2, 4, 6) decreases with increasing Na2 O. Ω2 decreases rapidly with increasing Na2 O while Ω4 and Ω6 decrease slowly. Both the fluorescent lifetime and the radiative transition rate increase with increasing Na2 O. Fluorescence spectra of the 4 I 13/2 to 4 I 15/2 transition have been measured and the change with Na2 O content is discussed. It is found that the full width at half-maximum decreases with increasing Na2 O. 相似文献
9.
Takashi Harada Hiromichi Takebe Makoto Kuwabara 《Journal of the American Ceramic Society》2006,89(1):247-250
The glass transition temperature increases and the thermal expansion coefficient and density decrease with increasing B2 O3 concentration in a series of (100− x )(50BaO–50P2 O5 )− x B2 O3 where x =0–10 mol% for bulk samples. According to Raman spectroscopy, the bulk BaO–P2 O5 –B2 O3 (BaP–B) glasses consist of metaphosphate Q 2 units with ring-type metaborate, diborate, and PO4 –BO4 groups. X-ray photoelectron spectroscopy results reveal qualitatively that P–O–B bonds are formed at the surface of BaP–B glass samples ground in laboratory air over 6 mol% B2 O3 only. The P–O–B bonds are related to the suppression of the crystallization of powdered BaP–B glasses with >6 mol% B2 O3 during differential thermal analysis. 相似文献
10.
Emission properties of PbO–Bi2 O3 –Ga2 O3 glasses doped with Ho3+ were investigated for fiber-optic amplification at the 1.18 μm wavelength region. When the glasses were doped with Ho3+ ions only, there was a weak emission at 1.18 μm with a lifetime of ∼200 μs. However, when Yb3+ ions were codoped, the lifetime of the 1.18 μm emission increased to 630 μs together with a significant increase in intensity. A similar enhancement in the intensity and lifetimes was realized for the 2.05 μm emission. These effects are due to energy transfer from the Yb3+ :2 F5/2 to the Ho3+ :5 I6 level. Devitrification of the ternary PbO–Bi2 O3 –Ga2 O3 glasses was efficiently suppressed by adding 10 mol% GeO2 . Optimum Ho3+ concentration was ∼0.4 mol%, whereas Yb3+ ions can be added up to the solubility limit. 相似文献
11.
An investigation was made of the effect of TiO2 on the glassforming region and on the physical properties of glasses in the system Na2 O-B2 O3 -SiO2 TiO2 . Glasses containing up to 45 mole % TiO2 may be formed with an alkali content of 30 mole %. At lower alkali contents (10 mole % Na2 O) glasses may be formed containing up to 22 mole % TiO2 . The way in which the coefficient of linear thermal expansion and the transformation and softening temperatures are affected by TiO2 additions has been determined. 相似文献
12.
Immiscibility temperatures of Na2 O-B2 O3 -SiO glasses, with andwithout 1 mol% MoO3 , additions, were determined and the effect of MoO3 additions on the 65O°C immiscibility isotherms was established. In addition, immiscibility temperature and phase-separation morphology of an Na2 O-B2 O3 -SiO2 glass with progressive additions of MoO3 , were investigated. It was found that the addition of small amounts of MoO3 extends the immiscibility boundary of the system and raises the immiscibility temperature by ∼l8°C for each mol % MoO3 , addition. Analysis of phase-separation morphology suggests that the MoO3 , additions do not significantly alter the tie lines of phase separation in the system, although such additions cause a lowering of the viscosities and the glass-transition temperatures of these glasses. 相似文献
13.
Yangyang Ji Jingkui Liang Sishen Xie Yude Yu 《Journal of the American Ceramic Society》1995,78(3):765-768
The "subsolidus" phase relations at room temperature in the system CaO-B2 O3 -BaO are investigated. Specimens of various compositions were prepared from appropriate ratios of CaCO3 , B2 O3 , and BaCO3 , and fired from 780° to 1040°C according to their melting points. There are three ternary compounds in this system. The crystal structures of these compounds were determined by X-ray diffraction (XRD). CaBa2 (BO3 )2 and Ca5 Ba2 B10 O22 are monoclinic structures. The lattice constants a = 14.221 Å, b = 4.569 Å, c = 11.926 A, β= 99.947°, and V = 763.4 å3 for CaBa2 (BO3 )2 and a = 15.714 å, b = 6.184 å, c = 10.204 å, β= 93.954°, and V = 989.29 å3 for Ca5 Ba2 B10 O22 are obtained. The third compound, CaBa2 (B3 O6 )2 , is isostructural with the high form of BaB2 O4 with lattice constants a = 7.167 å and c = 35.298 å. Powder second harmonic generation efficiencies of these ternary compounds were measured using a homemade apparatus. 相似文献
14.
Indra N. Chakraborty Robert A. Condrate Sr. 《Journal of the American Ceramic Society》1983,66(4):71-C-
Raman spectra were measured and analyzed for K2 O-B2 O3 -CeO2 glasses containing 85% and 65% B2 O3 . Structural changes, e.g. in the coordination of boron (3 to 4) and germanium (4 to 6), were noted from the spectra when composition was varied. 相似文献
15.
E. F. RIEBLING 《Journal of the American Ceramic Society》1967,50(1):46-53
Density (and some viscosity) data are presented for binary sodium borate melts containing as much as 60 mole % Na2 O and for ternary sodium silicoborate melts with B/Si <2.0 between 1000°C and 1300°C. The high-temperature partial molar volume analysis of the binary sodium borate melts reveals about 50% BO4 tetrahedra at the 40 mole % Na2 O composition, in agreement with recent NMR estimates for the binary glasses. No "boron anomaly" was found near 18 mole % Na2 O at high temperature. The synthetic partial molar volume model that agrees best with experiment for all ternary melts studied involves the presence of some BO4 tetrahedra, the percentage of which varies with composition. This ternary model involves a high degree of internal consistency. No tendency toward extensive micro-immiscibility was observed for ternary melts near the SiO2 ·B2 O3 binary. 相似文献
16.
The binary isopleth Na2 O.B2 O3 -SiO2 of the Na2 O-B2 O3 SiO2 ternary system has been investigated. A phase diagram is presented based upon data from differential thermal analysis studies of prepared glasses and direct observation of the melting behavior using solid-state video imaging. Phase equilibria relations in the Na2 O-B2 O3 -SiO2 ternary system have been reassessed by combining information from this study with existing data from the literature. A revised liquidus surface for the ternary is presented in which the form of the isotherms is updated. 相似文献
17.
A molecular dynamic simulation was performed for sodium borate glasses containing a small amount of Eu2 O3 to investigate the local structures of cations in glass. A new potential VB-B in the form -A exp[-C(r - 0.239)2 ] was added to the regular modified Born-Mayer-Huggins-type potentials, ΦB-B , ΦB-O , and ΦO-O, to account for the directional tendency of the borate network structure. With this potential added, both the radial distribution of sodium borate glasses observed by small-angle X-ray diffraction and the change in coordination number of boron with sodium content obtained by NMR agreed well with the simulation. The average coordination number of Ed3+ ions in the simulated glasses varied from 7.5 to 8.6, depending on the composition of the host sodium borate glasses. The inhomogeneous line width of the 5 D0 -7 Fz emission peak also changed, depending on the sodium content, with a maximum at 18 mol% Naz O content; this result agrees well with experimental data obtained from laser-induced fluorescence spectra. 相似文献
18.
Nucleation and crystal growth rates and properties were studied in a two-stage heat treatment process for Fe2 O3 -CaO-SiO2 glasses. Glass transition (Tg ) and crystallization temperatures (T c ) for the glasses lay between about 612.0° and 710.0°C, and 858.5° and 905.0°C, respectively, and magnetite was the main crystal phase. For a glass of 40Fe2 O3 . 20CaO·40SiO2 (in wt%) the maximum nucleation rate was (68.6 ± 7) × 106 /mm3 ·s at 700°C, and the maximum crystal growth rate was 9.0 nm/min1/2 at 1000°C. The mean crystal size of the magnetite increased from 30 to 140 nm with variation of nucleation and crystal growth conditions. The glass showed the maxima in saturation magnetization and coercive force, 212.1 × Wb/m2 and 30.8 × 103 A/m, when heat-treated for 4 h at 1000°C and 1050°C, respectively. The variation of the saturation magnetization could be quantitatively interpreted well in terms of the volume fraction of the magnetite, whereas that of the coercive forces could be explained only qualitatively in terms of the particle size of the magnetite. Hysteresis losses showed the maximum value of 1493 W/m3 when heat-treated at 1000°C for 4 h prenucleated at 700°C for 60 min, and increased linearly with increasing heat treatment time under a magnetic field up to 800 × 103 A/m. 相似文献
19.
Shinichi Sakida Satoshi Hayakawa Toshinobu Yoko 《Journal of the American Ceramic Society》2001,84(4):836-842
The structures of M2 O3 –TeO2 (M = Al and Ga) glasses have been investigated by means of 125 Te, 27 Al, and 71 Ga NMR spectroscopies. The structural units of respective cations in M2 O3 –TeO2 glasses were quantitatively analyzed. The fractions of TeO4 trigonal bipyramid, AlO6 and GaO6 octahedra decreased and those of TeO3 trigonal pyramid, AlO4 , AlO5 , and GaO4 polyhedra increased with increasing M2 O3 content. Based on the local structures around Te, Al, and Ga atoms, the structure models of M2 O3 –TeO2 glasses were proposed. 相似文献
20.
John M. Jewell Paige L. Higby Ishwar D. Aggarwal 《Journal of the American Ceramic Society》1994,77(3):697-700
Barium gallogermanate glasses were prepared with substitutions of Al2 O3 , Y2 O3 , La2 O3 , and Gd2 O3 for Ga2 O3 . The effects of these substitutions on the glass transformation temperature, viscosity, thermal expansion, and molar volume have been determined. The changes in properties associated with each substitutional ion are consistent with structural roles reported for these ions in other glasses. Aluminum acts as an intermediate with [AlO4 – ] tetrahedra substituting directly for [GaO4 – ] tetrahedra. Yttrium and gadolinium act as "atypical" modifier ions because of their large field strengths. Finally, the properties of the La2 O3 -substituted glasses indicate a possible dual structural role for La3+ ions in these glasses. 相似文献