Effect of oxygen pressure on the orthorhombic-tetragonal transition in the high-temperature superconductorYBa2Cu3

Detwinning and Retwinning of YBa2Cu3O7-δ Single Crystals with Variable Oxygen Stoichiometry

“…The P-T-ö diagram of YBa 2 Cu 3 0 7 _ 0 suggests that both the temperature Ttr and the oxygen content 7-ö at Ttr decrease with decreasing partial oxygen pressure [13,14]. Untwinned orthorhombic crystal with reduced oxygen content could be obtained under uniaxial pressure by lowering the partial oxygen pressure.…”

Optimization of Flux Pinning in Bulk Melt Textured 1-2-3 Superconductors: Bringing Dislocations under Control

“…Accordingly, annealing at higher temperatures (900±930 C) in 0.2±1 atm oxygen results in the annihilation of the stacking faults. [20,21] Two driving forces are required in the material for the nucleation and growth of stacking faults: 1) a thermodynamic driving force, Ñm, where m is the chemical potential associated to the intercalation of a double chain CuO x layer in the structure (in fact, the large splitting widths observed in transmission electron microscopy (TEM) studies are relevant to a negative stacking fault energy that can be associated to a local phase transformation to the Y124 phase [22] ), and 2) a mechanical driving force, s (s is the re- [17], crosses: tetragonal-to-orthorhombic transition line for Y123 [18].…”

Oxide Superconductors

“…15-9, obtained from the work of Specht et al (1988). This, and other data obtained over a wider range of Oxygen stoichiometry of the YBa 2 Cu 3 O 7 _,5 system as a function of the oxygen partial pressure and the temperature.…”

“…This, and other data obtained over a wider range of Oxygen stoichiometry of the YBa 2 Cu 3 O 7 _,5 system as a function of the oxygen partial pressure and the temperature. The contours correspond to lines of constant oxygen content, and the orthorhombic-to-tetragonal phase boundary is shown as a dashed line (after Specht et al 1988). …”