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1.
The glass transformation temperature, thermal expansion coefficient, dc electrical conductivity, and IR transmission have been measured for four series of lead halosilicate glasses of the general composition (65– x )PbO· x PbX2 ·35 SiO2 (X=F, Cl, Br, I). Although results of these and other measurements suggest that the halide ions play similar structural roles in the glass, there appear to be significant differences in physical property behavior between glasses containing F− anions and those containing the other three halide anions. These results are explained by a proposed model incorporating both bridging and nonbridging halide species. 相似文献
2.
The absorption coefficient values of several silicate glasses in the IR radiation range were determined. Four methods were employed in this study: (1) direct transmission by CO2 laser, (2) direct transmission through ultrathin sections using an IR spectrometer, (3) glass particle dispersions in KBr pressed pellets, and (4) IR reflection spectral analysis. Wide variations in values were observed for some of these techniques. The reasons for the variations were explored, and evidence is presented to support the conclusion that the reflection measurements and the low-power transmission technique yield accurate values. The pellet technique was found to possess too many experimental variables which could not be controlled and gave erroneous data. The damage produced by direct transmission of high-power radiation was severe and introduced effects which gave spurious results. 相似文献
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Setsuhisa Tanabe Naohiro Saga Kazuyuki Hirao Teiichi Hanada† 《Journal of the American Ceramic Society》1990,73(6):1733-1736
SiO2 –Al2 O3–Eu2 O3 glasses were prepared for the composition 50siO2 ·(50 – x )Al2 O3·x Eu2 O3 , and their density, sound velocity, and elastic modulus were measured. The chemical shift of the AIK a band emission spectra and the isomer shift of 151 Eu by Mössbauer effect were obtained to determine the coordination states of Al3+ and Eu3+ ions in these glasses. It was found that the coordination number of Eu3+ ions was 12 and that the average coordination number of A13+ ions was almost 5 in these glasses. By introducing Eu2 O3 , the packing of constituent ions was strongly enhanced and the elastic modulus increased in this system. The compositional dependence of the molar volume and elastic modulus were explained by these states of high coordination number for Eu3+ and low coordination number for Al3+ ions compared with those in the corresponding M2 O3 crystals. 相似文献
5.
采用传统的高温熔融法制备了80GeO2–20RO (R=Ca, Sr, Ba)掺铋锗酸盐玻璃。研究了铋掺杂锗酸盐玻璃超宽带近红外发光性质,探讨了铋离子掺杂玻璃超宽带发光机理。结果表明:在808 nm激光激发下,铋掺杂锗酸盐玻璃随着碱土金属离子半径增加,中心波长为1300 nm的发射强度逐渐降低;在690 nm激光激发下,铋掺杂锗酸盐玻璃的近红外发射覆盖从900 nm到2000 nm波段但不呈现正态分布,荧光半高宽达428 nm。随着碱土金属离子半径的增加,其近红外发射中心位置逐渐向长波方向移动,推测近红外发光可能源于两种不同形式铋的发光中心。铋掺杂的锗酸盐玻璃具有良好的光学性能,较宽的荧光半高宽,将成为未来超宽带光纤放大器的增益介质。 相似文献
6.
Jong Heo David Lam George H. Sigel Jr. Edgar A. Mendoza David A. Hensley 《Journal of the American Ceramic Society》1992,75(2):277-281
Structural development of tellurite glasses with the addition of Li2 O and Na2 O has been studied using infrared, Raman, and X-ray photoelectron spectroscopies. The increase in intensity of the peak at 755 cm−1 in the infrared spectra as compared to the peak at 620 cm −1 suggests the transformation of TeO4 building units to TeO3 pyramids with the addition of alkali oxide. Proposed structural change is further supported by the strong compositional dependence of the 755-cm−1 peak in the Raman spectra as well as by the formation of a shoulder in the O 1 s peak of X-ray photoelectron spectra. In contrast to alkali silicate glasses, formation of nonbridging oxygens with the addition of alkali oxide is not observed. 相似文献
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本研究利用溶胶-凝胶技术制备Y-La-Si-O-N氧氮玻璃配合料,在1大气压N2气氛中1600℃左右温度熔制,制备出表观呈灰黑色透明的Y-La-Si-O-N系统氧氮玻璃。实验结果表明氧氮玻璃含氮量为6.7-10.9at%;显微硬度Hv为3.5-6.47GPa;断裂韧性为0.64-1.38MPam^1/2,Tg在1000℃以上,膨胀系数为1.05×10^-6℃^-1. 相似文献
8.
Biprodas Dutta Robert H. Magruder III Robert A. Weeks Donald L. Kinser 《Journal of the American Ceramic Society》1990,73(4):938-941
Thermally stimulated polarization and depolarization current (TSPC/TSDC) measurements were made on lead halide silicate glasses having compositions (65 − x )PbO· x PbX2 ·35SiO2 where x = 0, 0.1, 2, 10 and X = F, CI, Br, and I. The addition of halogen ions to lead silicate glasses gives rise to a new high-temperature TSDC peak in the vicinity of the peak previously observed in binary lead silicate glasses. The integrated area of the new peak is dependent on the amount and type of halogen ion present in the glass and does not saturate in the temperature range of our measurements. This new peak is attributed to space charge polarization of halogen ions. 相似文献
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Vinh Q. Nguyen Jas S. Sanghera Ishwar D. Aggarwal Isabel K. Lloyd 《Journal of the American Ceramic Society》2000,83(4):855-859
The physical properties of glasses in the Ge30 As10 Se(60— x ) Te x system with x = 25, 28, 30, and 35 at.% Te, the Ge30 As10 Se30 Te(30— y ) I y system with y = 5, 10, 20, and 30 at.% I, the Ge30 As10 Se35 Te(25— z ) I z system with z = 2, 6, 10, and 20 at.% I, and the [Ge30 As10 Se30 Te30 ](100— w ) I w system with w = 0, 5, 10, and 20 at.% I have been investigated. The changes in the glass transition temperature, density, coefficient of thermal expansion, hardness, and viscosity are attributed to the delocalized metallic bonding character of Te in the substitution of Te for Se in the Ge-As-Se-Te glass system and the network-terminating role of iodine in the substitution of I for Te in the Ge-As-Se-Te-I glass system, respectively. 相似文献
10.
Heidi L. Rutz Delbert E. Day Charles F. Spencer Jr. 《Journal of the American Ceramic Society》1990,73(6):1788-1790
In the Y2 O3 –Al2 O3 –B2 O3 system, homogeneous glasses were obtained from compositions containing from 50 to 65 mol% B2 O3 . The density, refractive index, and thermal expansion increase as Y2 O3 replaces either B2 O3 or Al2 O3 . These glasses have a dilatometric softening temperature above 665°, and below 300°C their dc electrical resistivity exceeds that of fused silica. The infrared absorption spectra indicate that BO3 , BO4 , and AlO4 , groups are present in these glasses. 相似文献
11.
Jinglin Tan Jufang Shao Cuiping Tian Zhiman Liao Ping Yan 《Journal of surfactants and detergents》2019,22(1):125-130
The effect of sodium halide on aggregation behavior of four cationic silicone surfactants, Si3mamCl, Si4mamCl, Si4PyCl, and Si4minCl, in solution was investigated using surface tension and conductivity measurements. The ability of sodium halide (NaCl, NaBr, and NaI) to reduce critical micelle concentration (CMC) values was in the order NaI > NaBr > NaCl. However, the γCMC values of the cationic silicone surfactants, Si4mamCl, Si4PyCl and Si4minCl, in sodium halide solution are almost the same as those of the salt-free system. The values of and are negative, indicating that the micellization process and adsorption of the four cationic silicone surfactants at the air-solution interface are spontaneous. 相似文献
12.
Structure of Sodium Aluminosilicate Glasses 总被引:1,自引:0,他引:1
A series of sodium aluminosilicate glasses composed of varying ratios ( R ) of Al2 O3 /Na2 O (0.25 R 2.0) has been simulated with the molecular dynamics technique using a tetrahedral form of a three-body interaction potential. Extrema in the activation energies for sodium diffusion and in the diffusion constants for all of the atomic species were observed for glasses with equal concentrations of Al2 O3 and Na2 O ( R = 1.0). These changes corresponded to the minimum observed experimentally in the activation energy for electrical conductivity and to the maximum observed in the viscosity for glasses with compositions of R = 1.0. The coordination of aluminum remained 4 over the entire compositional range, negating the need to invoke a coordination change of aluminum to explain the changes in the physical properties. The changes to the simulated physical properties as R passed through the equivalence point were attributed to the elimination of nonbridging oxygen, to the introduction of oxygen triclusters, and to changes in the distribution of ring structures within the glass networks. 相似文献
13.
Bimalendu N. Roy 《Journal of the American Ceramic Society》1990,73(4):846-855
Infrared spectroscopic studies of lead and alkaline-earth aluminosilicate glasses in the series x MO- x Al2 O3 (1 - 2 x )SiO2 M = Mg, Ca, Sr, Ba, and Pb; 0.05 x 0.275] were carried out in the range 2000 to 200 cm−1 . Three major absorption bands were observed in the 1100-, 800-, and 500-cm−1 regions. The frequency and the intensity of the 1100-cm−1 band varied linearly with composition. For a specific value of x , the changes in the frequency, intensity, and bandwidth of this band decreased in the order Mg > Ca > Sr > Pb > Ba and the apparent disorder in the glass structure, effected by the substitution of aluminum, increased in the direction Mg < Ca < Sr < Ba, with Pb in between Mg and Ca. The force constants and the bond orders of the Si-O and Al-O stretching vibrations in each of the glasses increased monotonically as Al/(Al + Si) decreased. 相似文献
14.
The glass formation region has been determined for the CaO-CaF2 -Al2 O3 ternary system. The glass transformation temperature of these glasses decreases as the CaF2 concentration increases, whereas the thermal expansion coefficient and electrical conductivity increase. MAS-NMR (magic-angle-spinning nuclear magnetic resonance) indicates that the aluminum ions in these glasses are in tetrahedral coordination. The structures of these glasses are proposed to be analogous to those of similar silicate glasses, with aluminum ions replacing silicon ions and fluorine acting as a nonbridging anion. 相似文献
15.
Ultrasonic velocities at 10 MHz have been measured in two series of lithium, sodium, and potassium phosphomolybdate glasses with two fixed P2 O5 concentrations. Elastic moduli, Poisson's ratio, and Debye temperature have been calculated. The composition dependence of most of the properties of lithium glasses exhibits a trend opposite to that of potassium glasses. Properties of sodium glasses lie between the other two alkali systems. Alkali oxide modification is suggested to be accompanied by ring reformation in lithium and sodium glasses. Ring size effects have been shown to account for all of the composition dependence. 相似文献
16.
Photochromic glasses having composition (SiO2)45(B2 O 3)35(Al2O3)7.5(Na2O)12.5(AgBr), (Cu2O) doped with (CoO) x , in which, x = 0, 0.006, 0.02 and 0.07 g were prepared using the conventional melt technique. The amorphous nature of these glass samples was confirmed using X-ray diffraction analysis at room temperature. The absorption measurements in the infrared region of the spectrum were recorded in the wave number range (4000–400) cm?1. Spectral reflectance and transmittance at normal incidence of the prepared glass samples were recorded with a spectrophotometer in the spectral range 200–2500 nm. Experimental and theoretical densities of the prepared glass samples were measured, calculated and compared. Analytical expressions were used to calculate the real and imaginary parts of the refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, average oscillator wavelength, and Abbe’s number were deduced and compared. Absorption dispersion parameters such as: optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter were calculated. Effects of doping with cobalt oxide CoO as a transition metal on linear and predicted nonlinear optical parameters were investigated and interpreted. Experimental results indicate that there is an optimum concentration of cobalt doping around 0.006 g. The optical band gap decreases with increasing doping and causes an increase in nonlinear optical parameters. Doping with cobalt oxide improves the linear and nonlinear optical properties of the prepared glasses. 相似文献
17.
用传统熔融冷却法制备ZnO-B_2O_3-Bi_2O_3,系统玻璃,采用X射线衍射法和差热分析法研究了玻璃的结构和玻璃的特征温度T_g和T_f,测试了玻璃的密度、热膨胀系数和介电常数等性能。结果表明,在ZnO-B_2O_3-Bi_2O_3系统玻璃中,当用B_2O_3逐步取代Bi_2O_3时,玻璃的特征温度T_g和T_f呈现逐渐升高的趋势,玻璃热膨胀系数由11.13×10~(-6)/℃减小至6.22×10~(-6)/℃,玻璃的密度由5.920 g/cm~3减小至4.114 g/cm~3,同时,玻璃的介电常数也有一定程度的下降。 相似文献
18.
磷酸盐玻璃中单掺杂镱(Yb)、铒(Er)、钕(Nd)等稀土元素,对其光谱特性,荧光寿命,低温特性等将产生重要影响。也会改善杂质对磷酸盐玻离性能的影响。 相似文献
19.
INDRA N. CHAKRABORTY JAMES E. SHELBY ROBERT A. CONDRATE SR. 《Journal of the American Ceramic Society》1984,67(12):782-785
Glass formation limits were determined for the lanthanum borate glasses. Stable immiscibility prevents the formation of clear glasses over the range 0 to 20 mol% La2 O3 , but excellent quality glasses could be formed between 20 and 28 mol% La2 O3 . Data are reported for the density, refractive index, thermal expansion coefficient, glass transformation and dilatometric softening temperatures, transformation range viscosity, helium permeability, and chemical durability of these glasses. A limited Raman and infrared spectroscopy study suggests that lanthanum plays a similar structural role in these glasses and in the related crystals. 相似文献
20.
Properties and Structure of Lead Fluorosilicate Glasses 总被引:1,自引:0,他引:1
An extensive glass-forming region has been determined for the lead fluorosilicate system. These glasses have a very high anionic (fluorine) conductivity. The value of 2 x 10-4 ω-1 .cm-1 at slightly less than 200°C found for one glass is the highest anionic conductivity reported to date in a glass. Glass transition temperatures, thermal expansion coefficients, and UV-visible spectra were also measured. Results of these measurements and melt-history studies will be discussed and related to a proposed structural model for the lead fluorosilicate glasses. 相似文献