Superconductor transition temperature

Crucibles of titanium nitride and zirconium nitride are utilized for the melting of lanthanum alloys. ZrN, HfN and TaN are also used as electrodes in electronic valves. Niobium and zirconium nitrides could be used as superconductors due to their relatively high superconductor transition temperatures of 16.8 and 10 K respectively. 

Niobium and zirconium nitrides have relatively high superconductor transition temperatures... 

Special Alloys. AHoys of tin with the rater metals, such as niobium, titanium, and 2kconium, have been developed. The single-phase alloy Nb Sn [12035-04-0] has the highest transition temperature of any known superconductor (18 K) and appears to keep its superconductivity in magnetic... 

Superconductivity is the loss of all electrical resistance when a substance is cooled below a certain characteristic transition temperature (Ts). It is thought that the low temperatures are required to reduce the effect of the vibrations of the atoms in their crystalline lattice. Superconductivity was first observed in 1911 in mercury, for which Ts = 4 K. Over the years, many other metallic superconductors were identified, some having transition temperatures as high as 23 K. However, low-temperature superconductors need to be cooled with liquid helium, which is very expensive. To use superconducting devices on a large scale, higher transition temperatures would be required. 

Niobium germanide, NbgGe, is a superconductor with a high transition temperature (T, = 20K). It is prepared by CVD by the coreduction of the chlorides as follows ... 

The metal alloy, niobium germanium (Nb3Ge), is another superconductor with a much lower transition temperature (20K) with well-established characteristics and good strength. It is deposited by CVD on an experimental basis by the reaction described in Ch. 6. 

One of the most exciting properties of some materials is superconductivity. Some complex metal oxides have the ability to conduct electricity free of any resistance, and thus free of power loss. Many materials are superconducting at very low temperatures (close to absolute zero), but recent work has moved the so-called transition temperature (where superconducting properties appear) to higher and higher values. There are still no superconductors that can operate at room temperature, but this goal is actively pursued. As more current is passed through... 

If transition temperatures other than those allowed by superconducting pure metals are required, two metallic layers can be deposited to form a bi-layer TES. In most cases, only one of the two metals is a superconductor. In this case, the Cooper pairs diffuse from... 

Keywords Phase transition temperature Debye temperature High-temperature superconductor. 

Another interesting application of the total energy approach involves superconductivity. For conventional superconductors, the 1957 theory of Bardeen, Cooper and Schrieffer [26] has been subject to extensive tests and has emerged as one of the most successful theories in physics. However, because the superconducting transition temperature Tc depends exponentially on the electron-phonon coupling parameter X and the electron-electron Coulomb parameter p, it has been difficult to predict new superconductors. The sensitivity is further enhanced because the net attractive electron-electron pairing interaction is proportional to X-p, so when these parameters are comparable, they need to be determined with precision. 

The successful prediction of superconductivity in the high pressure Si phases added much credibility to the total energy approach generally. It can be argued that Si is the best understood superconductor since the existence of the phases, their structure and lattice parameters, electronic structure, phonon spectrum, electron-phonon couplings, and superconducting transition temperatures were all predicted from first principles with the atomic number and atomic mass as the main input parameters. 

This work shows the exceptional physics that can be done with a STM operated at cryogenic temperatures and the availability of STMs working down to liquid helium temperature opens broad avenues of research in the coming years. No doubt that among the many future scientific experiments accessible with low temperature STMs, the real-space electronic characterization of the metal-superconductor transition in /c-phases of BEDT-TTF salts, because Tc > 4 K, as well as the study of magnetic ordering in MOMs, will certainly occupy a relevant position. 

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