Tables cuprate superconductors

Several other novel strategies have been employed for the synthesis of superconducting cuprates some of them were mentioned earlier while discussing the various methods. Especially noteworthy are the use of the combustion method and the alkali-flux method for cuprate synthesis. Superconducting infinite-layered cuprates seem to be possible only when prepared under high pressures because of bonding (structural) considerations [87, 88]. In Table 7 we list the various cuprate superconductors along with their properties and the preferred methods of synthesis. 

Table 9.1 General formulas of important homologous series of cuprate superconductors and derived hole concentration, p.

Table 9.3 Crystallographic data of important orthorhombic cuprate superconductors. The incommensurate modulation of the Bi compounds has been neglected.

Cuprate high-temperature superconductors are copper-containing perovskite-derived oxides. Many of these maintain the superconducting state to temperatures above that of liquid nitrogen (Table 8.1). The stmctures of the superconductors are built up of slices of perovskite type linked by slabs with stmctures (in the main) of the rock salt (NaCl) or fluorite (CaFj) type (Section 4.6). The copper valence in most compounds lies between the formal values of Cu and Cu ". 

Electrical and Structural Data of High-Tc Superconductors. In Tables 4.2-13 and 4.2-16 electrical and structural data, respectively, of selected high- Tc cuprates are summarized. The data were compiled on the basis of review articles [2.13-16]. In many cases the real stoichiometric coefficients of oxygen are a few tenths higher or lower than the one-digit numbers indicated in the formulas of the tables. The value A7[ is the difference between the temperatures at which the resistance reached 90% and 10% of the normal state resistance, respectively, during cooling of the sample p Q) is the residual resistivity expressed by the formula p T> Tc) = p(P) + piT) with p = dp/dT. 

A number of researchers have begun to prepare poly-mer/superconductor composites with the hope of improving the processibility and properties of the hybrid materials (see Table 37.1) [1-8], For example, polymeric matrices loaded with ceramic superconductor components have been used in a plastic extrusion process to prepare superconducting wires and filaments [5,6]. Moreover, hydrophobic polymers have been used as environmentally protective layers [7,8] to slow the parasitic corrosion reactions that occur when cuprate compounds are exposed to water, acids, carbon dioxide, and carbon monoxide. 

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