Oxygen composition, effect superconductivity

Superconductivity. The insulator-superconductor transition takes place near this composition probably as a result of the percolation of the hole doped clusters. At x = 6.342 small amounts of the material become superconducting (fig. 27b). Superconductivity under pressure A giant ATJAP effect has been measured at RT (sect. 5.4) indicating an increased compressibility at the T-0 transition due to the half-filled chains and strong oxygen-ordering effects. The effect disappears at LT where the mobility of oxygen freezes (fig. 58). 

LCO has been actively studied as a model system for elucidating the nature of the superconduction phenomenon in cuprate systems because of the relative simplicity of its chemical composition and structure. The HTSC studies of the effects of oxygen... 

The composition, structure and superconducting properties of high Tc oxide superconductors, La-Sr-Cu-0 and Y-Ba-Cu-0 systems have been investigated. From comparative studies of effects of partial replacements of metal sites by other elements, a low dimensional nature of conduction path was suggested in both oxide systems. Critical relevance of oxygen deficiency and the conditions of heat treatments to the evolution of superconductivity, is discussed in terms of the relatively large nonstoichiometry found in these systems. 

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