Growth of BSCCO 2212 crystals in flat dish-shaped crucibles

Abstract

We report the growth of undoped and Y- and Gd-doped Bi 2Sr 2CaCu 2O 8 (BSCCO 2212) crystals by the flux method in flat dish-shaped crucibles where the growth mechanism appears to be different from that observed in standard high form or conical crucibles. The crystals exhibited two different morphologies with two different properties. Thin plate crystals grew at the surface of the melt (type ‘A’), and others grew under the top layer as polygonal thick blocks (type ‘B’). The orientation and the habit of the ‘A’ crystals were dependent on the growth conditions, they were free from any detectable Al contamination or flux inclusions and were good quality 2212 crystals exhibiting high as-grown T c (onset) between 90 and 93 K with transition widths between 2 and 10 K. On the other hand, the polygonal blocks were mixed with flux and indicated a T c (onset) of 86 K with a broader transition width. The influence of the shape of the crucible and the possible growth processes are discussed.