共查询到20条相似文献,搜索用时 0 毫秒
1.
G. A. Lisovskii V. A. Saechnikov É. A. Chernyavskaya T. P. Yanukovich I. M. Mel’nichenko E. N. Poddenezhnyi 《Journal of Applied Spectroscopy》2000,67(2):369-372
We investigated the influence of fluorination of xerogel on the intensity of luminescence with a maximum at 1.9 eV attributable
to nonbridging oxygen atoms in gamma-quanta irradiated sol-gel quartzglasses. It is established that in samples with a high
content of hydroxyl groups (more than 8 ppm) the intensity of this luminescence correlates with the content of hydroxyl in
the initial samples. Fluorination of gels at the technological stage before sintering substantially reduces the number of
silanol groups, improves the quality of glass, and increases their radiative-optical stability.
Translated from Zhurnal Priklandoi Spektroskopii, Vol. 67, No. 2, pp. 266–268, March–April, 2000.
This work was carried out with financial support from the Belarusian Republican Foundation for Fundamental Research, project
F98-139. 相似文献
2.
V. A. Saechnikov É. A. Chernyavskaya G. A. Lisovskii T. P. Yanukovich I. M. Mel'nichenko E. N. Poddenezhnyi 《Journal of Applied Spectroscopy》2000,67(6):1063-1068
We consider the absorption, luminescence, and Raman spectra upon gamma-quanta irradiation of quartz glasses manufactured by a sol-gel technology. The influence of the change in a regime of synthesis of the glass on its radiation stability is considered. 相似文献
3.
Preparation and atomic oxygen erosion resistance of silica film formed on silicon rubber by sol-gel method 总被引:1,自引:0,他引:1
Based on the characteristic that silicon coupling agents have the capability to develop ‘molecular bridge’ in the interface of organic materials and inorganic materials, silica films were prepared on the surface of flexible silicon rubber by sol-gel method and the optical transmittance of the sample before and after atomic oxygen irradiation was tested. The surface morphology and structure of silica films were investigated by scanning electronic microscope (SEM) and Fourier transformed infrared spectroscopy (FTIR). The results indicated that the silica sol could easily form a uniform thin film on the surface of silicon rubber pretreated by high concentration silicon coupling agents, and the inorganic silica films could combine with organic silicon rubber without obvious delamination on the interface. 相似文献
4.
5.
A previously proposed model describing the trapping site of the interstitial atomic hydrogen in borate glasses is analyzed. In this model the atomic hydrogen is stabilized at the centers of oxygen polygons belonging to B–O ring structures in the glass network by van der Waals forces. The previously reported atomic hydrogen isothermal decay experimental data are discussed in the light of this microscopic model. A coupled differential equation system of the observed decay kinetics was solved numerically using the Runge Kutta method. The experimental untrapping activation energy of 0.7×10−19 J is in good agreement with the calculated results of dispersion interaction between the stabilized atomic hydrogen and the neighboring oxygen atoms at the vertices of hexagonal ring structures. 相似文献
6.
Using double glow plasma alloying technique, a multi-elements alloyed layer containing elements of Cr, Ni, Mo and Co was formed on the surface of pure iron. After undergoing suitable aging treatment followed solid solution treatment, the formed alloying layer keeps a good combination of corrosion resistance and wear resistance. The relationship between the process parameters of heat treatments and the properties of the formed Cr-Ni-Mo-Co alloying layer, such as the chemical composition, hardness, corrosion resistance and wear resistance, was investigated in this study. It was revealed that the formed alloying layer exhibits a better behavior than that of 304 stainless steel and pure iron by employing a suitable heat treatment system. The temperature employed in solid solution treatment is 1453 K (1180 °C) followed by water quenching and the aging temperature is 813 K (540 °C) followed by water cooling. 相似文献
7.
8.
Spectroscopic properties of Er3+:CBS (CdSO4+B2O3 and R2SO4+CdSO4+B2O3, R2SO4=Li2SO4.H2O, Na2SO4, K2SO4 and Gd2(SO4)3.8H2O) glasses are reported. The assigned energy level data of Er3+(4f
11) in these glasses are analysed in terms of a parametrized model Hamiltonian. The standard deviations of the data fits are
between 39 and 47 cm−1 so that the energy level schemes of the Er3+(4f
11) ions in borosulphate (CBS) glasses are reasonably well reproduced. Radiative properties for the fluorescent levels of Er3+:CBS glasses are determined by using the Judd-Ofelt theory. The potential laser transitions are identified with the help of
predicted radiative properties which are compared and discussed with similar results. 相似文献
9.
The structural and magnetic powders prepared by properties of barium ferrite the sol-gel method
下载免费PDF全文

In this paper,M-type hexagonal barium ferrite powders are synthesized using the sol-gel method.A dried precursor heated in air is analyzed in the temperature range from 50 to 1200 C using thermo-gravimetric analysis and differential scanning calorimetry.The effects of the additives and the cacinating temperature on the magnetic properties are investigated,and the results show that single-phase barium ferrite powders can be formed.After heat-treating at 950 C for 4h with 3 wt% additive,the coercivity and saturation magnetization are found to be 440 Oe and 57.9 emu/g,respectively. 相似文献
10.
用高温熔融法制备了不同Ho3+离子掺杂浓度65GeO2-12B2O-10BaO-10Na2O-3Al2O3-χHo2O3(χ=0.25,0.75,1.25mol%)锗酸盐玻璃。从吸收特性出发,应用McCumber理论计算了Ho3+离子能级5I8→5I7(~2.0μm)跃迁的吸收截面和5I7→5I8的受激发射截面。根据掺杂离子的浓度以及获得的吸收截面和受激发射截面得到Ho3+离子在此玻璃中的增益截面函数,从该函数可反映出材料的粒子数反转特性。获得的基本光学参数与其它掺杂的玻璃进行了比较,其吸收截面、发射截面和增益截面的最大值具有一定的优势。认为该玻璃在~2.0μm波段的中红外激光器中将有潜在的较大应用前景。 相似文献
11.
Spectral dependences of the coefficients of absorption by free carriers and of multiphoton absorption by a silicon lattice
in the region of the interstitial oxygen band at 5.8 μm are established. A procedure for measurement of the distribution of
oxygen and alloying impurities in silicon ingots is given. The effectiveness of the spectrometers developed for controlling
the segregation of impurities and nonstationary convection of the silicon melt in growing ingots by the Czochralski method
is shown.
Belarusian State University, 4, F. Skorina Ave., Minsk, 220080, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 5, pp. 655–659, September–October, 1997. 相似文献
12.
The electronic states of Cd-chalcogenide microcrystals embedded in GeO2 glasses are discussed through the photo-luminescence spectra obtained by steady-state and dynamical spectroscopies. The photoacoustic absorption spectra as well as the steady-state and transient absorption spectra are also presented briefly in order to bring about a better understanding of their electronic states. 相似文献
13.
T. Satyanarayana 《Journal of luminescence》2010,130(3):498-506
The glasses of the composition (39−x)BaO-xAl2O3-60P2O5:1.0Ho2O3 (in mol%) with x value ranging from 1.0 to 4.0 have been synthesized. The IR spectral studies of these glasses have indicated that there is a gradual transformation of Al3+ ions from tetrahedral to octahedral with increase in the concentration of Al2O3 up to 3.0 mol%. Optical absorption and fluorescence spectra (in the visible and NIR regions) of these glasses have been recorded at room temperature. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of Ho3+ ions in these glasses. From the luminescence spectra, various radiative properties like transition probability A, branching ratio βr, the radiative lifetime τr and emission cross-section σE for various emission levels of these glasses have been evaluated. The radiative lifetime of the 5S2→5I8 (green emission) transition has also been measured. The variations observed in these parameters have been discussed in the light of varying co-ordinations (tetrahedral and octahedral positions) of Al3+ ions in the glass network. The influence of hydroxyl groups on the luminescence efficiency of the transition 5S2→5I8 has also been discussed. Finally the optimum concentration of Al2O3 for getting maximum luminescence output has also been identified and reported. 相似文献
14.
Absorption and luminescence spectra of a 4-nitro-4-dimethylaminobutadiene molecule in binary solvents have been experimentally
obtained and investigated. Formation of the absorption spectra is associated with a chromophore grouping of the molecule in
a bent state, while the bathochromic shift of the band in the absorption spectrum is consistent with the theory of dipole-dipole
interaction of a bipolar molecule with solvent molecules. The fluorescence spectrum and its form and bathochromic shift depend
not only on the solvent polarity but also on the proportion and kind of binary mixture of solvents. For a certain proportion
of the binary solvent, radiation has been generated at λ=610 nm in pumping by a nitrogen laser.
Reported at the International Conference on Luminescence, November, 22–24, 1994, Moscow.
Belarusian State University, 4, F. Skorina Ave., Minsk, 220080, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 1, pp. 119–121, January–February, 1997. 相似文献
15.
Vladimir P. Solovjov Brent W. Webb 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(7):1205-1212
A reduced SLW model consisting of a single gray gas and a clear gas is developed as an efficient spectral method for modeling radiation transfer in high temperature gases. It is shown that the SLW-1 model is not simply a reduction of the SLW method to the case of a single gray gas. Good accuracy can be achieved by the optimal choice of the model’s gray gas absorption coefficient and its weight by application of the Absorption-Line Blackbody Distribution Function (ALBDF), which is calculated with a high-resolution spectral database. Different approaches to the construction of the SLW-1 model are shown. The SLW-1 model absorption spectrum still has the line structure corresponding to the real gas absorption spectrum, which is maintained with fixed spectral intervals in non-uniform medium with the help of the reference approach. The validation of the SLW-1 model is performed by comparison with (i) benchmark solutions obtained by the line-by-line method and (ii) the SLW method with a large number of gray gases. Formulation of the SLW-1 method is also shown with the Two-Flux method and P-1 differential approximation. 相似文献
16.
A K Sood K Sankaran Y Hariharan S Vijayalakshmi V Sankara Sastry S Kalavathi J Janaki 《Pramana》1988,31(5):389-397
We report infrared absorption of Y1Ba2Cu3O7−δ
as a function of oxygen stoichiometry (0<δ<1) and copper substitution by iron in the spectral range of 450–700 cm−1. The strong bands associated with Cu-O vibrations undergo significant changes in their frequencies and intensities asδ is varied across the orthorhombic to tetragonal phase. These changes coupled with those arising as a result of doping with
iron has helped in identifying the nature of the vibrational modes. 相似文献
17.
The growth of E1′ centers in a variety of natural and synthetic quartz crystals has been investigated by employing the electron spin resonance technique. It has been reported that the growth of E1′ centers, formed by irradiation and subsequent annealing at 300 °C for 15 min, scale with the concentration of the aluminum hole center, [AlO4]0, till a limit. Later, the E1′ centers show saturation even when the [AlO4]0-center continues to grow. For quartz with low efficiency of the formation of [AlO4]0-center or irradiated with low accumulated doses, the intensity of E1′ center was small where not all oxygen vacancies are converted to the E1′ center. Thus, besides the availability of a number of oxygen vacancy sites, the number of holes released from the [AlO4]0-center plays an important role in the formation of E1′ centers in quartz. 相似文献
18.
19.
F. Docchio 《Il Nuovo Cimento D》1991,13(1):87-98
Summary The analysis of the spatial and temporal dynamics of plasmas induced in liquids by nanosecond laser pulses, based on a model
of moving breakdown combined with a model of distributed shielding, is herein presented. Time- and space-resolved characteristics
of energy absorption and transmission are evaluated with the aid of the two models, and compared to experimental findings
available in the literature. In particular, energy absorbed per unit length and volume of the plasma column, time-resolved
transmission, and energy input-output characteristics of the plasma, are considered. The dependence of the plasma attenuation
of the focusing geometry is also discussed. The relevance of this analysis in relation to laser photodisruption is finally
outlined. 相似文献
20.
Ting LUO Yi ZHANG Xing-guo LI Li LIN Yue-yang ZHANG Qing-rong FENG 《Frontiers of Physics in China》2008,3(1):55-60
Systematic studies of synthesizing behaviors of sol-gel YBa2Cu3O7−x
samples in flowing oxygen atmosphere and their superconductivity have been performed. A set of high temperature ρ-T curves has been obtained for the whole synthesizing process. After four rounds of synthesizing, the resistivity of the sample
was around ρ=1.00×10−3Ω · cm at room temperature. The ρ-T curve of the fourth round shows that the orthorhombic to tetragonal phase transformation of the sample occurs around 600
°C, which is lower than that of the YBa2Cu3O7−x
sample prepared by conventional solid-state reaction method. Other measurements, such as X-ray diffraction, SEM measurement
and low temperature R-T and M-T measurement, were also performed. And the R-T and M-T measurement results suggest that during the synthesizing process, there exist some state at which the sample has better superconductivity
than the other states. Moreover, we found screw dislocations presenting on the sample broken surface from the SEM images.
This will change the concept that the screw dislocations can only grow on the surface of the YBCO thin films and single crystals.
相似文献