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1.
The retarded elasticity was investigated for B2O3GeO2 glasses having network structure in the glass transition range by using a compressive method. The compliance (J∞) determined at the final stage of each measurement displayed a maximum for roughly constant viscosity (η ? 1014 P) in all the B2O3GeO2 glasses and was simulated by the same equation applied for AsS glasses reported in a previous paper [1]. , where are parameters and ηG is the viscosity related to the retarded elasticity. The terms (k1/η) and (nk1/η) are assumed to be equal to one for all their values exceeding one. For B2O3GeO2 glasses, the deformation due to the retarded elasticity could be alloted to two structural elements: the first element related to the term and the second element related to the term . The values of showed almost no variance with the glass composition, but had a minimum at the composition of 50 mol% GeO2. These data suggest that the contribution of the second element is the smallest at B2O3/GeO2 = 1. The values of k2 were close to that of As2S3 glass having the network structure. k1 and n (or nk1) were almost constant regardless of the composition, respectively. These data suggest that the inhibition due to the viscosity starts at an approximately constant viscosity in B2O3GeO2 glasses. 相似文献
2.
Combined X-ray and neutron diffraction experiments were performed on the Ni60Nb40 metallic glass samples prepared by rapid quenching from the melt with natural Ninat and isotope 58Ni, respectively. The partial structure factors were separated for the three kinds of atomic pairs: NiNi, NiNb and NbNb. The partial distribution functions were calculated by means of Fourier transformation and the following atomic distances were obtained: and . The values nNiNi=7.3, nNiNb=4.5, nNbNi=6.8 and nNbNb=5.4 were obtained for the number of nearest neighbours. 相似文献
3.
Tōru Komiyama 《Journal of Non》1975,18(1):107-118
The behavior of the phonon-assisted energy transfer between trivalent rare-earth ions in glasses was investigated. The ions Eu3+ and Tb3+ as energy donors and Yb3+ as acceptor were selected. The energy gap between the levels of the donor and acceptor was estimated on the basis of the energy diagram of each ion determined from absorption and emission spectra. The probability for the transfers of (Eu, 5D0-7F6): (Yb, ) and (Tb, 5D4-7F0): (Yb, ) in silicate, borosilicate, phosphate and germanate glasses was measured in the temperature range of liquid-nitrogen temperature - 650K. The probability of transfer was the smallest in phosphate glass and B2O3 had the effect of increasing it. In germanate glass the dependence of the probability of the energy gap was relatively weak. These results were correlated to the difference in the phonon energy and the strength of the electron-lattice coupling in each glass. 相似文献
4.
The analysis of gas in the chemical transport reaction of VO2 using TeCl4 as a transport agent was carried out with a quadrupole mass spectrometer. In the transport reaction from 600 to 500°C, it was found that the oxygen and vanadium of VO2 were transported in the form of VOCl3 and TeOCl2 gases; the transport reaction was . The transport reaction from 900°C to 800°C was assumed to be . In the transport at high temperature, the oxygen partial pressure estimated from the mass spectrum was considerably higher than that in equilibrium with VO2 phase. In this paper a study of the chemical transport of the system VO2-TeCl4 is presented. 相似文献
5.
An X-ray photoemission and Auger electron spectroscopy study of the electronic structure of Pd80Ge20 alloy in its glassy and crystalline states is reported. The glassy state shows some modifications in the valence band structure, symmetry of the Pd spin-orbit doublet and a shift in M45-V-V Auger transition of Pd. Analysis of the chemical shifts in the core-level binding energies of the constituents indicates negligible charge transfer from the metalloid atom (Ge) to d-band of the Pd. 相似文献
6.
Koichi Matsumoto 《Journal of Crystal Growth》1977,40(2):291-297
Single crystals of SnO2 were grown by the chemical transport method from the powder prepared by heating hydrous stannic oxide. The transport reactions were carried out when iodine and sulfur were simultaneously used as transporting agent, and fine crystals of a few millimeters in dimensions were grown after a ten-day transport; the transport proceeded from 1100°C (charge) to 900°C part in a silica ampoule. The crystals were identified as SnO2 (cassiterite) by the Weissenberg method. Thermodynamic calculations led to the equilibrium for this transport reaction. 相似文献
7.
The diffusion-reaction growth melts fluxed with PbO-B2O3-Fe2O3, has been extended to include a thermally-activated diffusion term. The fluxed melt had a lower PbO : B2O3 ratio (11 : 1) than that generally used (≈16 : 1) for garnet LPE films. Measured growth rates for LPE films, produced from melts with four different concentrations of CaGe-Substituted EuTm2Fe5O2 garnet, fit the model with: diffusivity, ; reactivity, ; viscosity, ; and concentration, for rotation rates ω (rpm) = 36 to 196 in the growth temperature range 890 to 965°C. It is shown that the garnet melt concentration terms are the most critical ones in determining the growth rate, hence the activation energy (heat of solution) for the equilibruim concentration is reported to five significant figures. Evaluating the D and the K effects by both a numerical (results given above) and an analytic method demonstrates that these parameters are least critical in determining the growth rate in this case. 相似文献
8.
J.J. Hauser 《Journal of Non》1977,23(1):21-41
The planar and transverse electrical resistivity of amorphous carbon (a-C) films getter-sputtered at low temperature (77–95 K) is well-fitted by the expression The exponent T0 being approximately the same in both cases (≈ 7 × 107 K) suggests that the amorphous films are isotropic. Films thinner than 600 Å display a two-dimensional hopping conductivity from which one deduces a density of states N(EF) at the Fermi level of 1018 eV?1 cm?3 and a radius of the localized wave functions (a) of 12 Å. Tunneling experiments and optical absorption measurements are consistent with a pseudogap of approximately 0.8 eV. Electron diffraction experiments indicate that a-C films consist of a mixture of diamond and graphite bonds; this fact taken in the light of the other experiments would suggest that the graphite bonds act as the localized conduction states. 相似文献
9.
Richard W. Griffith 《Journal of Non》1977,24(3):413-426
For a non-polar amorphous semiconductor such as a-Si, we derive an explixit formula for (?Eg/?T)V, the derivative with temperature of the mobility gap Eg at constant volume V. Within the framework of second-order perturbation theory for the electron-phonon (eφ) interaction, many of our physical assumptions are fundamentally different from those that apply to the crystal phase. The principal ingredients of our model are: (1) the random-phase-model (RPM); (2) the principle of non-conservation of particle momentum in the eφ interaction; and (3) the deformation potential approximation. Narrowing of Eg is found with increasing values of the temperature T. At very low T, we have , where cV(T) is the average lattice specific heat per mode at constant volume and ¢A is a positive dimensionless quantity in the model. By contrast with low-temperature behavior of the crystal, this result implies that the mobility gap at constant volume dynamically responds to the phonomic “gas” of the disordered lattice. The high-T limit yields behavior quite similar to that of the crystal phase. We find , where kB is Boltzmann's constant and the parameter x, expected to be confined to the interval , measures the admixture of the optical-phonon and acoustical-phonon coupling strengths. 相似文献
10.
Ag2S forms with GeS2 stable glasses over a wide range of compositions (0–55% Ag2S mol%). In the same system, more complex glasses obtained by dissolving silver iodide have been synthesized with up to 50 mol% AgI.Raman spectra are presented and a vibrational assignment in terms of bridging and non-bridging sulfur has been made. The electrical conductivity of these glasses has been measured over a temperature range (?50°C? + 50°C) and for various compositions by the complex impedance diagram method. At 25°C, the conductivity reached a maximum value of 6 × 10?3 Ω?1 cm?1. Whatever the glass used, the same limit value of conductivity ) and activation energy () are obtained for the highest content of silver iodide. A conduction mechanism is proposed. 相似文献
11.
Spinodal decomposition during continuous cooling of the PbOB2O3Al2O3 quasi-binary glass system was analysed by numerical integration of Cook's differential equation (which includes the contribution of random density fluctuations) for small angle X-ray scattering (SAXS) intensity. The SAXS curves derived from the calculations have a wide range of k-Fourier components (0 < k < kc) for which a positive amplification factor occurs and they show a “crossover” point at . The wavenumber which receives maximal amplification, km, increases with the cooling rate, Q, as , with n = 10.9. This Q dependence of km is similar to that predicted by Huston et al., however our results show a higher value of n. The dependence on Q and km of the SAXS intensity I(km) was also deduced. The measurements of SAXS curves were performed on glass samples prepared by the splat-cooling technique. Because of the difficulties which arise in the determination of the cooling rate of the samples, the only experimental results that could be compared with the theory are the km dependence of I and the value of kc. These results are satisfactorily understood in terms of the present analysis. 相似文献
12.
The elastic moduli and their variation with pressure have been determined for three glass compositions in the K2OSiO2 glass system. The results may be summarized:
Property/Composition | 0.15K2O–0.85SiO2 | 0.25K2O–0.75SiO2 | 0.33K2O–0.67SiO2 |
Shear modulus | 266 | 241 | 231 |
Bulk modulus | 310 | 283 | 273 |
Young's modulus | 620 | 564 | 540 |
( | ?5.1 | ?4.4 | ?3.9 |
( | ?2.8 | ?2.6 | ?2.5 |
Poisson's ratio σ | 0.167 | 0.168 | 0.170 |
() | |||
(kb?1) | ?1.5 | ?1.2 | ?0.95 |