Direct observation of 18O tracer diffusion in a YBa2Cu3Oy single crystal by secondary ion mass spectrometry

Direct observation of 18O tracer diffusion by secondary ion mass spectrometry (SIMS) was made on a single crystal of YBa2Cu3Oy with an array of steps on the stairlike surface. The unique distribution of the diffused 18O in the ab-plane and in the c-axis direction was shown visually as a mapped image, which revealed some fundamental processes on the oxygen penetration through the surface and diffusion in the inner crystal. It was found that at 530degC, the diffusion coefficient in an ab-plane is larger than that in a c-axis direction by more than five orders of magnitude. (author)