DIRECT OBSERVATION OF O-18 TRACER DIFFUSION IN A YBA2CU3OY SINGLE-CRYSTAL BY SECONDARY ION MASS-SPECTROMETRY

Direct observation of O-18 tracer diffusion by secondary ion mass spectrometry (SIMS) was made on a single crystal of YBa2Cu3O(y) with an array of steps on the stairlike surface. The unique distribution of the diffused O-18 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 530-degrees-C, the diffusion coefficient in an ab-plane is larger than that in a c-axis direction by more than five orders of magnitude.