Liquid formation at hte peritectic temperature in superconducting YBa sub 2 Cu sub 3 O sub 7 minus x; Observation of a new phase YBa sub 4 CuAlO sub 8

This paper reports, in the system Y-Ba- Cu-O partial melting of peritectically decomposing YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (123) used to produce a bulk material of high critical current density when the material was aligned. The liquid formation mechanism and its relation to reaction with alumina refractory was studied. A previously unreported phase of the approximate stoichiometric ration Y:Ba:Cu:Al = 1:4:1:1 (YBa{sub 4}CuAlO{sub 8}) was detected. The crystal structure was determined to be tetragonal with lattice parameters {alpha}{sub 0} = b{sub 0} = 1.651 nm, c{sub 0} = 1.793 nm. The 1411 phase bears a close structural relationship to BaCuO{sub 2}.