1999•Superconductor Science and TechnologyRequires access
Phase and microstructure evolution in the process of the composite Bi-2212-(Sr, Ca)3Al2O6glass-ceramics formation
Pavel E. Kazin, Viktor V. Poltavets, Yu. D. Tret’yakov, Martin Jansen, Bert H. Freitag, W. Mader
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Abstract
Devitrification of glass with a cation ratio corresponding to the composition {Bi 2.1 Sr 2 CaCu 2 O x +0.4Sr 1.7 Ca 1.3 Al 2 O 6 } was studied. At temperatures below 600 °C, the phases crystallized in the order Bi-2201, Cu 2 O, CaO, (Sr,Ca) 3 Bi 2 O 6 , while Al ions concentrated in the remaining glass. Above 600 °C, Bi-2212 and (Sr,Ca) 3 Al 2 O 6 formed simultaneously, so that at 750 °C, the two-phase composite Bi-2212-(Sr,Ca) 3 Al 2 O 6 was obtained that contained grains of the aluminate phase 0.03-0.3 µm in size. The Al-rich phase surplus increased the stability of the glass and accelerated Bi-2212 phase formation, while development of superconductivity in Bi-2212 was slowed down. It was shown that composite glass-ceramics with bulk superconductivity could be obtained at temperatures above 850 °C.