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31.
Hugo R. Fernandes Dilshat U. Tulyaganov Ashutosh Goel José M. F. Ferreira 《Journal of Thermal Analysis and Calorimetry》2011,103(3):827-834
This article aims to shed some light on the structure and thermo-physical properties of lithium disilicate glasses in the
system Li2O–SiO2–Al2O3–K2O. A glass with nominal composition 23Li2O–77SiO2 (mol%) (labelled as L23S77) and glasses containing Al2O3 and K2O with SiO2/Li2O molar ratios (3.13–4.88) were produced by conventional melt-quenching technique in bulk and frit forms. The glass-ceramics
(GCs) were obtained from nucleation and crystallisation of monolithic bulk glasses as well as via sintering and crystallisation
of glass powder compacts. The structure of glasses as investigated by magic angle spinning-nuclear magnetic resonance (MAS-NMR)
depict the role of Al2O3 as glass network former with four-fold coordination, i.e., Al(IV) species while silicon exists predominantly as a mixture
of Q
3
and Q
4
(Si) structural units. The qualitative as well as quantitative crystalline phase evolution in glasses was followed by differential
thermal analysis (DTA), X-ray diffraction (XRD) adjoined with Rietveld-reference intensity ratio (R.I.R.) method, Fourier
transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The possible correlation amongst structural
features of glasses, phase composition and thermo-physical properties of GCs has been discussed. 相似文献
32.
Hong Chen J.A. Peters Yue Pan J.J. Heremans N. Goel S.J. Chung M.B. Santos W. Van Roy G. Borghs 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):374
Spin–orbit interaction in two-dimensional electron systems can lead to a spin-dependent reflection of carriers off a lithographic barrier. Scattering of a spin-unpolarized beam from the barrier leads to the creation of two fully spin-polarized side beams in addition to an unpolarized specularly reflected beam. We experimentally demonstrate a method to create spin-polarized beams of ballistic electrons in mesoscopic samples fabricated on InSb/InAlSb and InAs/AlGaSb heterostructures. We describe two geometries, one open and one closed, in which the spin-dependent reflection and spin-dependent semiclassical trajectories were observed. 相似文献
33.
M.J. Singh S.K. Goel R. Shanker D.O. Kataria N. Madhavan P. Sugathan J.J. Das D.K. Avasthi A.K. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):7-13
Measurements were carried out to deduce the transverse kinetic energies of highly charged argon recoil ions produced in single
collisions of 120 MeV ions with argon atoms in which the post collision charge states of the projectiles were not determined. A time of flight
spectrometer was designed and fabricated to detect the charge states of recoils. Experimental procedures for optimizing the
spectrometer for extraction, transmission and detection of recoils are described. A simple approach for determining the transverse
kinetic energy of the recoil ions from FWHM of the peaks is reported. This method is shown to be independent of the choice
of collision partners and requires only the knowledge of the physical values of “optimized parameters” of time-of-flight spectrometer
used in the experiment. The transverse kinetic energy of the recoil ions determined from the present approach is found to
vary from 0.03 eV for to 4.02 eV for Ar10+. These values are compared with the results reported by earlier workers and are shown to follow a q2-behaviour up to a charge state q
=8+ of the recoil ions.
Received: 5 February 1998 / Revised: 8 June 1998 / Accepted: 11 June 1998 相似文献
34.
C. V. Chaudhari K. A. Dubey Y. K. Bhardwaj Virendra Kumar N. K. Goel S. Sabharwal 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(1):47-53
Radiation induced grafting of acrylonitrile (ACN) on ethylene-propene diene terpolymer (EPDM) rubber film was investigated
by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, type of solvent and
monomer content on extent of grafting was studied. From the kinetic studies a mathematical relation R
g
α[M]0.7
D
0.68 showing non-linear relationship for rate of grafting with monomer concentration and dose was deduced. The grafted samples
showed increased hardness and oil resistance. 相似文献
35.
J.-C. Alder H. Behrens F.W. Brasse W. Fehrenbach J. Gayler S.P. Goel R. Haidan V. Korbel J. May M. Merkwitz 《Nuclear Physics B》1975,99(1):1-12
Results on the reaction ep→e′nπ+ are presented in the mass range 1.355 ?W ?1.775 GeV at q2=1GeV2 and in the range 1.415 ? W ? 1.595 GeV at q2=0.6 GeV2. From the angular distribution of the π+ meson the polarization terms σu + ?σL, σp and σI have been determined in the range of production angles 0 <θπ+ ?63° 相似文献
36.
37.
We have measured the near-normal incidence reflectivity of single crystal RuO2 (rutile) for 6 -axis and ⊥ -axis at room temperature in the photon energy range 0.5 – 9.5 eV. From a Kramers-Kronig analysis of the reflectivity we have obtained the spectral dependence of the real, ?1(ω), and imaginary, ?2(ω), parts of the complex dielectric constant. Comparison with recent band structure and density of states calculations and past experimental studies of related solids has enabled us to gain further insight into the nature of the oxygen -electrons and metal -electrons in this material. 相似文献
38.
Palladium (II) catalyzed cleavage of phenyl-antimony and phenyl-phosphorus groups of Ph3Sb and Ph3P under carbon-dioxide or CO/NO atmosphere leading to benzoic acid, has been demonstrated. 相似文献
39.
The downward movement of water in the soil due to 1971 monsoon precipitation and supplemental surface irrigation has been traced at about forty-five sites in Western Uttar Pradesh, using a thin layer of moisture tagged with tritiated water. The tritiated layer was found to move down to different depths at different sites. The movement, averaged over the forty sites is found to be 96 cm, indicating that the average recharge for the year 1971 (a year of normal monsoon) was 21.5 cm of water. 相似文献
40.
The temperature variation of the second order Raman spectra of RbI has been theoretically studied in three basic symmetries on the basis of the modified Born and Bradburn theory. The phonon frequencies and corresponding eigenvectors have been determined at the room temperature by employing a three body force shell model. It has been assumed that the major factor which governs the temperature dependence of Raman intensity is the occupation number and the changes in the phonon eigen data and the polarizability parameters with temperature have been ignored. Calculations have been made at three temperatures namely, 300,90 and 23 K and the theoretical results have been compared to the experimental Raman spectra. 相似文献