Superconductive compounds

The key to the superconducting properties of these ceramics seems to be the presence of planes of copper and oxygen atoms bonded to one another. The significance of the other atoms in the lattice seems to be to provide a stmctural framework for the copper and oxygen atoms. Thus, in the superconducting compound YBa2Cu30, the substitution of other rare earths for yttrium resrrlts in little change in the properties of the material. 

About 20 HTe superconducting compounds and copper oxidic systems Correlations of the Cu NQR/NMR data with the Cu( Zn) emission Mossbauer data for HTSC lattices as a tool for the determination of atomic charges... 

Potassium dibismuthide, alloy-like superconducting compound, 4 18t Potassium dichromate, 6 538 14 559 manufacture, 6 541 for purifying carbon dioxide streams, 4 815... 

This transfer of superconductive compounds charged within the body to a superconductive template prepared within the mushroom will not occur in three-dimensional space no actual physical transfer will be visible, as the organically processed superconductive material will bond itself to the mushroom template through a higher spatial dimension. 

Research studies on other binary and ternary oxide systems were quite limited during the next 20 years. In a 1952 comprehensive review, entitled "A Search for New Superconducting Compounds", B. 

Figure 31 A schematic representation of the 1 -2-3 structure, or the 90 K superconducting compound, Ba2YCu3Oe+x. Note the Cu(l) square-planar chains and the Cu(2) puckered planes in the structure.

In a previous section, it was shown how the substitution of Y3+ for Las+ was an important step towards the formation of new compounds for superconductivity research. This substitution attempt led to the discovery of the 1-2-3 (or 90 K) superconducting compound. Substitutions similar to that proposed by Muller and Bednorz are now outlined. The type of chemical substitutions, based on atomic radii, which were proposed for La2Cu04, are presented in the following Table 11. 

This chapter will describe primarily the crystal chemistry and crystallography of the superconducting compounds in this family. I begin with descriptions of the basic compounds BaBiOs and BaPbOs. Next, the Ba(Pb,Bi)Os solid solutions, which have been studied in some detail, and the relatively new Ba(Pb,Sb)Os system are described. Finally, I describe what is known about (Ba,K)BiOs, which, although it is a material of considerable importance, is not completely characterized as of yet because of the difficulties in materials preparation and crystal growth. 

Tseng, D., and Ruckenstein, E., Some improvement in the Tc of bismuth-based superconducting compounds, Materials Letters 8 69 (1989). 

Compound Semiconductors. The niobium-based superconducting compounds lead us naturally into another use for intermetallics—namely, semiconductors. This topic, too, was introduced earlier in this chapter (cf. Section 6.1.1.4 and 6.1.1.5), and we shall build upon those principles here to describe the semiconducting properties of compounds, ceramics, and glasses. The classification of intermetallics as ceramics... 

Fig. 17. Pictorial representation of intercalated superconducting compound of 2-dimensional graphite (carbon atoms interconnected with solid lines each line represents a pair of covalent bond) interleaved with potassium (circles) which ionizes easily to K. and provide free electrons . According to the model, COVALON conduction takes place within the graphite plane and affects the COVALON on the adjacent graphite plane through plasmon waves provided by the free electrons from the potassium metal.

Table 2 shows the known RT2B2C compounds (R Sc, Y, La, Th, or 4f or 5f elements T 3d, 4d, or 5d elements). As many as six compounds of this type are known for R = Ce (Mazumdar and Nagarajan, 2005) as well as for La. Table 3 contains the superconducting compounds listed in Table 2 and their superconducting transition temperatures Tc and, if existing, the magnetic ordering tempera-... 

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