Metals superconducting properties

The metal has unusual superconductive properties. As little as 1 percent gadolinium improves the workability and resistance of iron, chromium, and related alloys to high temperatures and oxidation. 

Because they exhibit interplay of magnetic and superconducting properties, the formation and crystal chemistry of MRgMy4B4 compounds have been examined. Ternary rare-earth and actinide (Th, U, Pu)-transition metal borides of the approxi-... 

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... 

Interestingly, if the C50 fullerene doped by alkali metals is rapidly cooled down to the liquid nitrogen temperature, polymerization does not occur. Only monomeric anion-radical salts are obtained. Warming up these monomers to 80-160 K results in dimerization polymerization does not take place. The dimer (KCgo)2 is dielectric (Pekker et al. 1995). It has been shown that the tris(anion)-radical Cgo can polymerize too. Particularly, Na2CsCgo forms a polymer that maintains superconducting properties (Mizuki et al. 1994). 

As mentioned before, we shall use small molecules to introduce the fundamentals for more complex molecules, the real core of this book, which will be listed in the next section. Such molecules form solids with remarkable properties (metallicity, superconductivity, ferromagnetism, etc.), some of them at ambient conditions or at much lower hydrostatic pressures than those found for H2 and N2, and some technological applications have been already developed, deserving the name of functional materials. Most of the molecules studied in this book are planar, or nearly planar, which means that the synthesized materials reveal a strong 2D structural character, although the physical properties can be strongly ID, and because of this 2D distribution we shall study surfaces and interfaces in detail. In particular, interfaces play a crucial role in the intrinsic properties of crystalline molecular organic materials and Chapter 4 is devoted to them. 

CT solids of fullerene Cgo with a number of different inorganic cations have shown metallic or superconducting properties (for superconductivity, see Sect. 5.2.3). Among the fullerene metals, the best known families are MCso anion radical salts... 

The exciting discovery of the metal-like properties and superconducting behaviour of the non-metallic polymer poly (sulfur nitride) (or polythiazyl), (SN), in 1973 sparked much activity in sulfur-nitrogen chemistry.This interest continues as a result of the prediction that molecular chains incorporating thiazyl units could serve as molecular wires in the development of nanoscale technology. 

In a normal metal (N) coupled to a superconductor (S), superconducting properties are locally induced by the proximity effect. The characteristic energy scale of this proximity superconductivity is given by the minimum of the bulk superconductor energy gap A and the Thouless energy ec ... 

The superconducting properties induced in the normal metal manifest themselves in many different ways, including energy-dependent transport properties and a modification of the local density of states. For instance, the conductance of a normal conductor connected to a superconducting electrode shows a striking re-entrant behavior [4]. At non-zero temperature and/or bias, the conductance of the normal metal is enhanced as compared to the normal-state. At zero temperature and zero bias, the expected conductance coincides with the normal-state value. The conductance has therefore a non-monotonous behavior. 

The highly symmetrical perovskite structure is very common for MM X3 type compounds. Some of the many hundreds of such compounds are listed in Table 5.6. Because of their important ferroelectric, ferromagnetic, and superconducting properties, many compounds have been synthesized varying the ratios of metals to optimize desired properties. New compounds are reported frequently. We will discuss structures related to perovskite in Sections 5.3.5, 5.3.6, 5.3.7, 5.4.11, 5.4.12, and 5.4.13. 

Intense efforts in the last decade have exhaustively mapped the electronic and superconducting properties of intercalated alkali fullerides and the occurrence of the metal-antiferromagnetic insulator transition as a function of inter -fullerene separation, orientational order/disorder, valence state, orbital degeneracy, low-symmetry distortions and metal-C60 interactions [6-12]. 

Tanigaki K., Prassides K. Conducting and superconducting properties of alkali metal-C6o fullerides. J Mater Chem 1995 5 1515-27. 

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