Evidence for existence of two different phases in Bi1.8Pb0.2Sr-2Ca2Cu3Ox,

Abstract

The elaborated and well characterized samples of Bi1.8Pb0.2Sr2Ca2Cu3Ox (2223 phase), as prepared, quenched from a partially melting state, and after melting, were studied carefully by X-ray diffraction (XRD), thermal analysis, electron diffraction (ED), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) microanalysis. Some evidence for the existence of two different phases in the 2223 phase has been obtained, in which one has incommensurate modulation and the other has none. Our experiment preliminarily gives the conditions for the existence of the two different phases. The phase with incommensurate modulation decomposes before melting, and the phase without it can exist in partially melting state. Based on the above fact, we tried to grow the single crystal of the 2223 phase from a partially melting state and got a small one. Unfortunately, the crystal is very unstable.