| dc.description |
Devitrification of glass with a cation ratio corresponding to the composition {Bi<sub>2.1</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>x</sub>+0.4Sr<sub>1.7</sub>Ca<sub>1.3</sub>Al<sub>2</sub>O<sub>6</sub>} was studied. At temperatures below 600 °C, the phases crystallized in the order Bi-2201, Cu<sub>2</sub>O, CaO, (Sr,Ca)<sub>3</sub>Bi<sub>2</sub>O<sub>6</sub>, while Al ions concentrated in the remaining glass. Above 600 °C, Bi-2212 and (Sr,Ca)<sub>3</sub>Al<sub>2</sub>O<sub>6</sub> formed simultaneously, so that at 750 °C, the two-phase composite Bi-2212-(Sr,Ca)<sub>3</sub>Al<sub>2</sub>O<sub>6</sub> 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. |
