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Fabrication of ceramic Y1−xCaxBa2Cu4O8+δ and YBa2Cu3O7 superconductors from oxalate precursors at ambient pressure

1991; Elsevier BV; Volume: 173; Issue: 3-4 Linguagem: Inglês

10.1016/0921-4534(91)90370-e

1873-2143

K. Kellner, Xianzhong Wang, G. Gritzner, D. Bäuerle,

High-pressure geophysics and materials

Ceramic Y1−xCaxBa2Cu4O8+δ and YBa2Cu3O7 superconductors were prepared from coprecipitated oxalate precursor material. Calcination and firing at 820°C under atmospheric oxygen pressure yielded pure phase Ca2+ doped and undoped YBa2Cu4O8+δ superconducting material. The Tco values increased from 80 to 85 K with an increase in the Ca2+ content from x=0 to 0.1. YBa2Cu3O7 was obtained after calcination of the oxalates at 860°C and sintering at 920°C under ambient oxygen pressure. This superconductor had a Tco of 92 K with a transition width of 1 K.