EFFECT OF THE PREPARATION CONDITIONS UPON THE STABILIZATION OF THE SUPERCONDUCTING PROPERTIES OF BI(PB) SRCACUO

The present work is devoted to the study of the process conditions for producing Bi-containing high-temperature superconducting (HTSC) mater ials with sufficiently stable critical parameters and external effects . The sintering of HTSC ceramics under high pressure results in deform ation in the 2212 and 2223 phases and internal microstresses. The auth ors proposed a method for the thermocyclic treatment of HTSC ceramics for restoring the crystal structure of the phases, without altering th e elementary cell parameters, The thermogravimetry data studied in sta tic air atmosphere with a heating and cooling rate of 10 deg/min have revealed the insignificant (similar to 0.1% wt) loss of the mass of sa mples. The main technological parameters for producing highly disperse d chemical and structurally homogeneous powders and Bi-HTSC ceramics h ave been determined. The process of production of Bi-HTSC ceramics inc ludes the heat treatment of co-precipitated carbonates, the conversion of Ca and Sr carbonates to nitrates and the synthesis of HTSC phase i n an O-2-Ar atmosphere. Investigations of the surface and the bulk of HTSC Bi-ceramics by X-ray photoelectron spectroscopy have shown the hi gh homogeneity and stability of this material. No fracture of componen ts was detected after the samples had been kept in air for 6 months.