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51.
Superconductivity in ternary metallic glasses has been investigated using the model pseudopotential approach, which has been
found quite successful in explaining superconductivity in metals, binary alloys and binary glasses. It is observed that this
simple methodology successfully explains superconducting behaviour of ternary glasses without requiring the solution of Dirac
equation for a many body problem or estimation of various interactions as required in ab-initio pseudopotential theory. In
the present work superconducting state parameters of fourteen metallic glasses of (Ni-Zr)-M system (M=Ti, V, Co, Cu) have
been determined in the BCS-Eliashberg-McMillan framework. It is observed that addition of V, Co, and Cu as the third element
(M) to a binary metallic glass (Ni33 Zr67) causes the parameters λ,T
c, α, andN
0
V to decrease, and Coulomb pseudopotential (μ*) to increase with concentration of M, showing that the presence of third element (M) causes suppression of superconducting
behaviour of the alloy. The decrease inT
c with increasing concentration of third element (M) may be attributed to the modifications in density of states at the Fermi
levelN(E
F), and probable changes in the band structure of the alloy due to addition of the third element (M). Slight difference is
noticed when Ti is added to the Ni33 Zr67 alloy. In this caseT
c rises initially and then decreases with concentration of M, showing a peak at aboutx=0.05. This indicates that on addition of Ti, 3d states grow near the Fermi level and hence contribute substantially toN(E
F), favouring superconducting behaviour in this case. The present results forT
c show an excellent agreement with the experimental data. QuadraticT
c equations have been proposed, which provide successfully theT
c values of ternary metallic glasses under consideration.
Paper presented at National Conference on Current Trends in Condensed Matter Research, Warangal, India, September 20–22, 2004. 相似文献
52.
Renu Tripathi G.S. Pati M. Messall K. Salit M.S. Shahriar 《Optics Communications》2006,266(2):604-608
We report on experimental observation of electromagnetically induced transparency and slow-light (vg ≈ c/607) in atomic sodium vapor, as a potential medium for a recently proposed experiment on slow-light enhanced relative rotation sensing [Shahriar et al. Phys. Rev. Lett. (submitted for publication), http://arxiv.org/abs/quant-ph/0505192.]. We have performed an interferometric measurement of the index variation associated with a two-photon resonance to estimate the dispersion characteristics of the medium that are relevant to the slow-light based rotation sensing scheme. We also show that the presence of counter-propagating pump beams in an optical Sagnac loop produces a backward optical phase conjugation beam that can generate spurious signals, which may complicate the measurement of small rotations in the slow-light enhanced gyroscope. We identify techniques for overcoming this constraint. Conclusions reached from the results presented here will pave the way for designing and carrying out an experiment that will demonstrate the slow-light induced enhancement of rotation sensing. 相似文献
53.
Summary The complex Pt(bpyMe)Cl3 (bpyMe = N-methyl-2,2-bipyridylium cation) reacts with pyridine(py) to give cis-[Pt(bpy-Me) (py)Cl2]+, which on heating cyclometallates with loss of py to give Pt(bpyMe-H)Cl2; some Pt(py)2Cl2 is also formed. Pt(bpyMe)Cl3 reacts with 2,2-bipyridyl (bpy) to yield a mixture of [Pt(bpyMe-H)(bpy)]2+ and [Pt(bpy)2]2+. The analogous reactions with Pd(bpyMe)Cl3 proceed under very mild conditions to afford PdL2Cl2 (L2 = 2py, bpy). 相似文献
54.
J. P. Banerjee S. P. Pati S. K. Roy 《Applied Physics A: Materials Science & Processing》1984,35(2):125-129
The effect of mobile space charge on avalanche zone width and conversion efficiency of single drift region (SDR) indium phosphide impatts at 12 and 60 GHz has been investigated. The results show thatp
+nn+ InP diodes have a narrower avalanche zone and a higher conversion efficiency compared ton
+pp+ diodes for both the frequencies at normal operating current densities. The expansion of avalanche zone and efficiency degradation at high current levels are more pronounced inp
+nn+ at 12 GHz and inn
+pp+ at 60 GHz. 相似文献
55.
56.
3,3′-Dicarbomethoxy-2,2′-bipyridyl(DCMB)reacts with K2MCl4(M = Pd,Pt) to give M(DCMB)Cl2 and with RhCl3 to give the cis-[Rh(DCMB)2Cl2]+ ion. Attempts to prepare the tris (DCMB) complex with Rh(III) and analogous Co(III) complexes were unsuccessful. 相似文献
57.
58.
In unified gauge theories with massive “color” gluons, the physical requirement of maintaining “color” SU(3) as a global classification symmetry is shown to lead to the following restrictions: (i) the local unifying symmetry group must be of the form Gflavor?Gcolor; (ii) quarks are to be integer charged; (iii) the number of flavors is an integral multiple of the number of “colors”. 相似文献
59.
Mohan PJ Datta A Mallajosyula SS Pati SK 《The journal of physical chemistry. B》2006,110(37):18661-18664
Nucleobases (adenine (A), thymine (T), cytosine (C), and guanine (G)) trapped within two metal clusters such as Au(3) undergo expansion. Our investigation reveals that this primarily arises due to the concomitant increase in all the bond lengths in molecules. Such expansion of the molecules can be qualitatively understood on the basis of classical harmonic potentials in the bonds and loss of aromaticity in the rings. Specifically, the highly electronegative O and N elements in the base pairs anchor to Au atoms and form X-Au bonds, which leads to charge redistribution within the molecules. As a very important consequence of this, the nature of the hydrogen bonds (in Au(3)-A...T-Au(3) and in Au(3)-G...C-Au(3)) change substantially within these electrodes in comparison to gas-phase structures. These hydrogen bonds have a single-well potential energy profile (of the type N...H...O and N...H...N) instead of double-well potentials (like N-H...O or N-H...N/ N...H-N types). A detailed energy calculation along the proton movement pathway supports our conclusions. 相似文献
60.