-
8
-
-
4244142919
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-
D. B. Mitzi et al., to be published. Similar increases in Tc as Tms -> Tc + have recently been observed by H. A. Borges et al. [in Proceedings of the Eighteenth Yamada Conference on Superconductivity in Highly Correlated Fermion Systems, Sendai, Japan, 1987 (to be published)] in EuBa2_- (Cu1-y Zny ) Ox_ as functions of pressure and y. This increase is similar to that observed in V3_Si under pressure with decreasing martinsitic transition temperature Tm, and it is therefore strong evidence for an electron-phonon mechanism.
-
(1974)
Phys. Rev. Lett.
, vol.32
, pp. 766
-
-
Chu, C.W.1
Testardi, L.R.2
-
12
-
-
4243769901
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-
These papers discuss explicitly stiffness thresholds in chalcogenide alloys, where the stiffness background level is large because of large chalcogenide polarizabilities. Because of the small size and polarizability of oxygen ions the background level can be much lower in oxides, 26, L405, especially relative to melting points, which are higher. The low background stiffness level also is necessary for facile sample (de-)oxidation and annealing at temperatures as low as 450^degrC, so that the observation of these processes itself is direct evidence for the present model. Note that facile oxygen diffusion requires small activation energies, and that these are the expected result in the presence of cyclic coordinates, which do not depend on the harmonic approximation and which exist quite generally regardless of the local bonding geometry. Also in metals exchange and correlation volume forces shift soft modes to short wavelengths. In the phonon density of [Truncated]
-
(1986)
Phys. Rev. Lett.
, vol.57
, pp. 3233
-
-
Boolchand, P.1
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13
-
-
0009381964
-
-
An intense soft mode at 150 cm-1_ in YBa2 Cu3 O7_ is greatly reduced in YBa2 Cu3 O6_ ( Tc = 0 ).
-
(1987)
Phys. Rev. B
, vol.36
, pp. 2294
-
-
Rhyne, J.J.1
-
22
-
-
84927438924
-
-
I. K. Schuller et al., Solid State Commun. (to be published).
-
-
-
-
24
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-
84927438921
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-
M. F. Thorpe, private communication.
-
-
-
-
28
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84927438910
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W. Weber and L. F. Mattheiss, unpublished.
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-
-
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29
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0000236262
-
Structural model of Raman ‘‘defect’’ bands of vitreous silica
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Mathematical models of superelastic (underconstrained) lattices may have special symmetries:, 33, 3289, A puzzling feature of samples with Tc> 50 K is the ability of a sintered powder or an amorphous film to oxidize at high temperature into the correct polycrystalline structure. This may result from application of pattern selection of superelastic lattices by the principle of marginal stability: E. Ben-Jacob, E. J. Garboczi, M. F. Thorpe, Phys. Rev. B, N. Goldenfeld, B. G. Kotliar, J. S. Langer, Phys. Rev. Lett., 53, 2110, An extreme example of a defective superelastic material is the fluorinated Y-Ba-Cu-O alloy, which shows superconductive behavior which changes drastically after heating and cooling:, S. R. Ovshinsky, R. T. Young, D. D. Allred, G. DeMaggio, and G. A. Van der Leeden, Phys. Rev. Lett., 58, 2579, Note that 1
-
(1978)
Physical Review B
, vol.35
, pp. 6409
-
-
Phillips, J.C.1
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