Residual surface stress measurements in YBa2Cu3Ox superconductors

XRD and residual surface stress (sin2 ψ) measurements were carried out on YBa2Cu3Ox superconductors with varying oxygen stoichiometry (6.3 < x < 7.0). Slopes of the surface strain versus sin2 ψ were plotted against oxygen content for certain reflections. Compressional surface stress has been found along the c-axis, while a tensile surface stress has been observed along the ab-plane. Both surface stresses were found to vary slightly with oxygen content. These findings qualitatively agree with a very small hydrostatic pressure effect on Tc for fully oxygenated YBa2Cu3Ox (x = 7) compared to oxygen deficient material at the surface.