A series of 18O tracer in-diffusion experiments was performed on metalorganic chemical vapor deposition grown Pb(Zr,Ti)O3 films. Before 18O incorporation, the samples were pre-equilibrated in 16O2; at the same temperature and total pressure used for the subsequent 18O2 isotope-exchange annealing. The final 18O depth profiles were obtained by using secondary ion mass spectroscopy, which provided a depth resolution of 3 to 5Å. The secondary ion mass spectrometry results indicated that the 18O tracer diffusivity varied, as a function of depth from the film surface (figure 28), in a manner that was inconsistent with a combined grain boundary and lattice diffusion mechanism. Based upon a previously-developed model for point-defect equilibrium in metal titanate thin films, simulations of 18O tracer diffusion into these thin films were described that were consistent with the experimental results.

18O Tracer Diffusion in Pb(Zr,Ti)O3 Thin Films - a Probe of Local Oxygen Vacancy Concentration. R.V.Wang, P.C.McIntyre: Journal of Applied Physics, 2005, 97[2], 023508 (8pp)

Figure 28

Tracer Diffusivity of 18O in Pb(Zr,Ti)O3

(Upper curve: bulk diffusion, lower curve: surface diffusion)