Phase stability of the mixed rare-earth yttrium/erbium and yttrium/ytterbium barium cuprates, RE0.5RE ' 0.5Ba2Cu3O7-x (RE = rare-earth), and 'YBa2Cu3O7-x (YBCO)+BaF2'

摘要

A thermodynamic study of the phase stability of the mixed rare-earth barium cuprates, RE0.5RE'0.5Ba2Cu3O7-x (RE/ RE'BCO, RE = Y, RE' = Er, Yb) and 'YBCO + 25 wt.% BaF2' was carried out over the temperature range 800-960 degreesC and pO(2) range 3.0 x 10(-4) to 2.1 x 10(-1) atm O-2, using a coulometric titration technique. At temperatures, T, less than the peritectic temperature, T-p, the phase stabilities of the mixed rare-earth compounds lie between the two single rare-earth parent systems. However, at T > T-p the phase stabilities of the mixed rare-earth compounds depend on the solubilities of the rare-earths in the melt. The stability of 'YBCO + BaF2' is reduced compared to pure YBCO and is very close to pure ErBa2Cu3O7-x (ErBCO). (C) 2002 Elsevier Science B.V. All rights reserved. [References: 17]