Fast growth of Bi2Sr2Ca2Cu3O10+x and Bi2Sr2CaCu2O8+x thin crystals at the surface of KCl fluxes

Abstract

We report a novel technique to grow crystals of the high-temperature superconductor Bi2Sr2Ca2Cu3O10+x and Bi2Sr2CaCu2O8+x (2223 and 2212 BSCCO phases), both pure and Pb substituted. The technique, based on chemical transport in a thermal gradient in molten KCl, is simple and inexpensive, and yields a continuous output of crystals, with growth times of a few minutes, i.e., orders of magnitude shorter than conventional flux methods. Depending on melt aging, crystals of either the pure 2223 or the pure 2212 BSCCO phases are obtained, having zero-resistance temperature of 105 and 90 K, respectively, and a transport critical current density of 104 A cm−2 at liquid nitrogen temperature.

Enhanced flux pinning from CuO inclusions in Bi2Sr2CaCu2Oy crystals

“…The enhanced flux pinning due to the incorporation of CuO may explain why J c is high ͑10 5 -10 6 A/cm 2 ͒ at low temperature for the Bi2212 thin crystals grown on KCl flux as reported in Ref. 16. The authors acknowledge financial support from the Australian Research Council, Energy Research and Development Corporation, Department of Energy of NSW, Electrical Supply Association of Australia, and Metal Manufactures Ltd.…”

“…This growth phenomenon is similar to that reported for the growth of Bi-Sr-Ca-Cu-O crystals at the KCl flux surface. 15,16 In our experiments, high temperatures ͑above 850°C͒ were used for the crystal growth. We found that, above this temperature, only Bi2212 crystals can be formed.…”

Floating Zone Growth of Bi2Sr2Ca2Cu3Oy Superconductor

“…Since Bi-2223 has a very narrow crystallization field [1,14], growth by self-flux was thought to be almost impossible. There were a few attempts to prepare Pb-free and Pb-doped Bi-2223 single crystals using molten KCl salt [18,19]. Only very small samples with dimensions up to 100ˆ100 µm 2 in (a,b) plane and thickness of 1-5 µm along c-axis were obtained.…”

On the Mechanism of Cuprate Crystal Growth: The Role of Mixed Metal Carbonates

“…The introduction of potassium ions causes depression of the melting point of the mixed carbonate phase, leading to target phase evolution at a lower temperature. Although suggestions of associate phase melting point depression with K + /Na + present during calcination have appeared recently, [ 16,[21][22][23] ] the mechanism has not been explicitly demonstrated. Monovalent cation-rich syntheses have also been demonstrated in molten salts, [ 24,25 ] thus the nature of the growth described here can be thought of as an amalgam of the two synthetic approaches.…”