Cation (63Ni) diffusion in YBa2Cu3O7- epitaxial films

The diffusion of Ni63 has been measured in YBa2Cu3O7- epitaxial thin films on (100) SrTiO3 substrates in the 550-650°C range (orthorhombic phase) in O2 pressure of 1 bar, keeping in the 0.3-0.4 range. The diffusion behavior is described by D=1.3 exp[(-2.7 eV)/kT] cm2/sec and is many orders of magnitude slower than anion (oxygen) diffusion reported in the literature. A diffusion mechanism involving thermal vacancies and atomic jumps in diagonal directions of the type 110, 301, and 031 is proposed for long-range diffusion of cations occupying the Cu sites. © 1990 The American Physical Society.