Solid superconducting

Of course, condensed phases also exliibit interesting physical properties such as electronic, magnetic, and mechanical phenomena that are not observed in the gas or liquid phase. Conductivity issues are generally not studied in isolated molecular species, but are actively examined in solids. Recent work in solids has focused on dramatic conductivity changes in superconducting solids. Superconducting solids have resistivities that are identically zero below some transition temperature [1, 9, 10]. These systems caimot be characterized by interactions over a few atomic species. Rather, the phenomenon involves a collective mode characterized by a phase representative of the entire solid. 

Electronic Structure of Solids Fluorides Solid-state Chemistry Halides Solid-state Chemistry Macrocyclic Ligands Metallic Materials Deposition Metal-organic Precursors Oxides Solid-state Chemistry Periodic Table Trends in the Properties of the Elements Sol-Gel Synthesis of Solids Sohds Characterization by Powder Diffraction Structure Property Maps for Inorganic Solids Superconductivity Thin Film Synthesis of Solids. 

Borides Sohd-state Chemistry Carbides Transition Metal Solid-state Chemistry Electronic Structure of Sohds Quasicrystals Structure Property Maps for Inorganic Solids Superconductivity Zintl Compounds. 

Electronic Structure of Main-group Compounds Electronic Stmcture of Organometallic Compounds Magnetism of Extended Arrays in Inorganic Solids Molecular Orbital Theory Solids Computer Modeling Structure Property Maps for Inorganic Solids Superconductivity. 

Hamiltonians equivalent to (1) have been used by many authors for the consideration of a wide variety of problems which relate to the interaction of electrons or excitons with the locaJ environment in solids [22-25]. The model with a Hamiltonian containing the terms describing the interaction between excitons or electrons also allows for the use of NDCPA. For example, the Hamiltonian (1) in which the electron-electron interaction terms axe taken into account becomes equivalent to the Hamiltonians (for instance, of Holstein type) of some theories of superconductivity [26-28]. 

NMR instrumentation consists of three chief components a magnet, a spectrometer console, and a probe. While in the past much solid state NMR research was conducted on home-built equipment, the current trend is toward the acquisition of commercial systems. The magnets used for solid state NMR applications generally are superconducting solenoids with a cylindrical bore of 89-mm diameter. The most common field strengths available, 4.7, 7.0, 9.4, and 11.7 Tesla, correspond to proton resonance frequencies near 200, 300, 400, and 500 MHz, respectively. 

Nonstoichiometry is relatively common among mixed metal oxides, in which more than one metal is present. In 1986 it was discovered that certain compounds of this type showed the phenomenon of superconductivity on cooling to about 100 K, their electrical resistance drops to zero (Figure 20.9). A typical formula here is YBa2Cu30 where x varies from 6.5 to 7.2, depending on the method of preparation of the solid. 

Not all observations are summarized by laws. There are many properties of matter (such as superconductivity, the ability of a few cold solids to conduct electricity without any resistance) that are currently at the forefront of research but are not described by grand laws that embrace hundreds of different compounds. A major current puzzle, which might be resolved in the future either hy finding the appropriate law or by detailed individual computation, is what determines the shapes of big protein molecules. Formulating a law is just one way, not the only way, of summarizing data. 

Metals and semiconductors are electronic conductors in which an electric current is carried by delocalized electrons. A metallic conductor is an electronic conductor in which the electrical conductivity decreases as the temperature is raised. A semiconductor is an electronic conductor in which the electrical conductivity increases as the temperature is raised. In most cases, a metallic conductor has a much higher electrical conductivity than a semiconductor, but it is the temperature dependence of the conductivity that distinguishes the two types of conductors. An insulator does not conduct electricity. A superconductor is a solid that has zero resistance to an electric current. Some metals become superconductors at very low temperatures, at about 20 K or less, and some compounds also show superconductivity (see Box 5.2). High-temperature superconductors have enormous technological potential because they offer the prospect of more efficient power transmission and the generation of high magnetic fields for use in transport systems (Fig. 3.42). 

Figure 5. Concentrational sections M gdr Rh, x)4B4 phase boundaries (schematic) of different structure types. Open circles indicate the occurrence of superconductivity filled symbols mean T = 1.2 K (no superconductivity observed above 1.2 K). Circles denote the existence of a CeCo4B4-type phase the thiek solid line represents the (metastable) phase boundary of the CeCo4B4-type structure the dashed line encloses the superconductivity region. ...

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