Effect of Oxygen Deficiency on the Crystal Structure and Superconducting Properties of the Ba₂YCu₃O_y

Abstract

Spacetimes which are conformally related to reducible 1+3 spacetimes are considered. We classify these spacetimes according to the conformal algebra of the underlying reducible spacetime, giving in each case canonical expressions for the metric and conformal Killing vectors, and providing physically meaningful examples.

Study of superconducting properties of oxygen deficient GdBa2Cu3O7−y by a heating cycle technique

“…It is worth comparing the data with that of YBa2Cu307_y. The y value at the onset of the semiconductivity is nearly the same as that derived from the quenched YBa2Cu307_y [ 6 ] which we believe are more uniform in the oxygendeficient stoichiometry. The results reported here and that reported in ref.…”

“…As the oxygen content is decreased, the material will enter the tetragonal phase, and superconductivity is destroyed. Very recently the role of oxygen on superconductivity has been examined on YBa2Cu307_y by several researchers [1][2][3][4][5][6][7][8]. Some works [9,10] show that GdBaECU307_y exhibits the same superconducting and structure characteristics as that of YBa2Cu307_y.…”

Phase formation and microstructure in Re1-x CaxBa2Cu3Oz (Re=Y, Eu, Er; x=0, 0.2, 0.3) superconducting ceramics

“…1). Partial transformation of orthorhombic to tetragonal structure was detected in YBCO samples when the Ca content increases to x=0.3, which is evaluated by splitting of the peaks in the range 2θ (32-33), 2θ (46-48), 2θ (58-59), using the method of Yoshimi Kubo, et al [11]. For the samples with calcium content x=0.3 and RE=Y we detected the appearance of additional reflections, which are connected with the formation of impurity phases BaCuO 2 -(file JCPDS-ICDD ë70-0441) and Y 2 BaCuO 5 (211) -(file JCPDS-ICDD ë81-1199), whereas in the samples with RE=Eu, Er at x=0.2, 0.3 we detected peaks of REBCO (123) and BaCuO 2 .…”

Processing Techniques for the 93 K Superconductor Ba 2 YCu 3 O 7

“…A remarkable feature of Ba2Y-Cu3Ox is that the stoichiometry in oxygen is readily variable over the range 6.0 ' x ' 7.0 (44)(45)(46)(47)(48). The stoichiometry as a function of temperature and ambient are shown in Fig.…”

“…After sintering, a final annealing in oxygen at 4000 to 6000C maximizes incorporation of oxygen. The anneal temperature is a compromise between higher temperatures where oxygen diffusion rates are higher and lower temperatures where the thermodynamic equilibrium favors higher oxygen contents (46). The anneal time depends on the sintered density and thickness of the part.…”