THE SUPERCONDUCTING STRUCTURE FRAGMENTS WITH TCI 180K. G.M. Kuz'micheva, S.I. Mukhina, Academy of Fine, Chemical Technology, Moscow, Russia; A.V. Mitin, Institute for Physical Problems, RAS, Moscow, Russia; E.P. Khlybov, Institute for High Pressure, Physics RAS, Troitzk, Russia

The study of the temperature variation of the electrical resistivity and the current-voltage characteristics of phases in the La-Sr-Ti-O, Ln-Sr-Nb-O, La-Mn-O, Ba-Sr-Pb-O, La-Pb-Re-O, Mg-Ti-O systems suggests that some compositions contain superconducting inclusions. The structure of superconducting inclusions (structure fragments) is coherently connected with structure of the non-superconducting phase and has different composition from one. A similar phenomena was observed in samples of the well-known system YBa₂Cu₃O₆₊, when increased from 0.2 to 0.5. The phases of compositions (Ln,Sr)xNbO₃-, (La,Sr)xTiO₃-, (La,Pb)xReO₃-, which belong to cubic bronzes of perovskite structure, contain superconducting structure fragments with Tci160 K, í.i 50K and í.i 60K, respectively. The phases (Ba,Sr)PbO₃ (perovskite structure) with í.i 70K and Mg(Mg,Ti)₂O₄ (spinel structure) with í.i 130K have the cubic symmetry. There are indications of the possible presence of superconducting fragments with Tci180K in the phase LaMnO₃₊ with rhomboedral perovskite structure. The depedence of the critical temperatures of the phases, Tc, and inclusions, í.i,, on formal charge of Ti, Nb, Pb, Re, Mn, Bi, Cu cations is found.