Superconducting reproduced

A potential alternative method to chemical synthesis of superconducting materials is offered by electrochemistry, particularly in view of the possibility that one has to achieve reproducible conditions. [Pg.512]

Fig. 1.5. Apparatus for demonstrating vacuum tunneling. The tunneling unit consists of a W tip and a Pt plate. Vibration isolation is achieved by magnetic levitation on a superconducting bowl. (Reproduced from Binnig et al., 1982a, with permission.)...

Because of the recent claims of room-temperature superconductivity in materials by several research groups, two additional criteria are further required to certify that a material is superconducting. These are long-term stability, and reproducibility in the preparation and physical property determination,... [Pg.6]

Paul" Chu, and others at University of Houston, also reproduced Zurich s I.B.M. research results (156). Bell Lab s confirmation of Bednorz and Muller s discovery of high Tc superconductivity in copper oxide compounds was published (157) in the Jan. 1987 issue of Physical Review Letters. The electrical resistivity data from their work showing an onset of superconductivity at 36.5 K for the composition Lax gSr0 2Cu04 is plotted as Figure 28. This product also showed a 60-70% Meissner effect. [Pg.77]

All of these procedures involve heating T1203 in non-sealed systems, and all are typified by superconducting product stoichiometries far different from the starting compositions. Again, in addition to safety concerns, little control of superconducting-phase composition and reproducibility of synthetic conditions is afforded by use of non-hermetically sealed reaction containers. The problem appears to be more complex than simply thallium reactant loss factors related to reaction kinetics are most likely quite important for the preparation of these metastable phases. [Pg.275]

The chemistry of this material turns out to be highly nonconventional, a fact which apparently prevented its discovery in the early days of research on Ba(Pb,Bi)Os. Superconductivity at 22K was first observed in the Ba-K-Bi-O system (38) in samples in which accidental melting resulted in trapped bubbles which acted to prevent the volatilization of K20 in parts of the sample. Those results were apparently not reproduced elsewhere. [Pg.411]

Figure 9.29—NM R magnets and samples. Robotic introduction (on the left) of a sample in solution placed in an NMR tube within a magnetic field generated by a superconducting coil and maintained at liquid helium temperature. (Reproduced by permission of Varian.) Electromagnet ton the right) of sizeable volume used for a special kind of sample the human body (part of an MRI instrument from the SMIS Society).

The present simple and partly postulative model seems to be able to reproduce the observed behaviour of the cuprate energetic characteristics. The possible coexistence of pseudogap with the superconducting gap of the other partner subsystem has been demonstrated. The transformation of the... [Pg.62]

Based on ac magnetic susceptibility and specific heat measurements, El Mas-salami et al. (1998a) claimed that they observed superconductivity in CeNi2B2C with Tc of about 0.1 K, which, however, has never been reproduced. [Pg.250]

Figure 4-40 In situ Raman spectra of a C6o film taken during rubidium doping (a) superconducting and (b) insulating. (Reproduced with permission from Ref. 58. Copyright 1992 American Chemical Society.)...

Figure 1. Cuprate-planar Cu charge extracted from the data, versus oxygen content x for YBa2Cu30x, as reported by Cava et al. (Ref. [1]) and by Jorgensen et al. (Ref. [2]). The two data sets do not follow the same line, because of calibration differences. The jump in the data of Ref. [1] occurs for only one datum, and is not reproduced in Ref. [2]. This calls into question claims that high-temperature superconductivity originates in the cuprate-planes.

This reproduces the shaip break of the metallic superconduction shown in Fig. 7.1. The absence of the sharp break in the cuprate resistance vs. temperature plot has been attributed to their short coherence lengths which give rise to large thermal fluctuations at the critical temperature. [Pg.37]

Fig. 12.26. A plot of the maximum superconducting critical temperature with time showing, in addition, the important discoveries of the Meissner effect, the microscopic Bardeen, Cooper and Schrieffer (BCS) theory and the temperature barrier, set by the boiling point of liquid nitrogen. (Reproduced by courtesy of Dr. J.M. Bell,...

Superconductivity in the multiphase quaternary borocarbide system Y-Ni-B-C has been recently reported [141,142], Earlier work on valence fluctuations in ternary borides RENiaB were studied and in the case of YNi4B, a weak but reproducible signal of superconductivity at Tc of 12 K was observed. This is the first report or discovery of a ternary superconducting phase of the elements Y, Ni and B with a high Tc value (Fig. 12.27). [Pg.949]

Fig. 25. Y 3d, Ba 3dv , Ba 4d, Ols and Cls XPS spectra obtained at the surface of the outer grains of the YBaiCujOv. j ceramics before (A) and after (B) the CF4 + 25% O2 plasma treatment (the peaks of the superconducting phase are noted S.C.) (reproduced with permission from J. Mat. Sri., 29 (1994) 4260 [108]).

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