Abstract: The ionic interdiffusions for Nb⁵⁺, Ni²⁺, Zr⁴⁺ and Ti⁴⁺ ions in the PNN/PZT functionally gradient piezoelectric materials were investigated
as a function of diffusion temperature and time respectively. The ionic compositional distribution profiles were examined by electron probe microbeam analysis (EPMA),
from which the thickness of the interdiffusion layers were determined. Based on a diffusion model of the overlapped diffusion solute from thin slub, the numerical
simulation of the ionic concentration distributions for Nb⁵⁺, Ni²⁺, Zr⁴⁺ and Ti⁴⁺ ions was carried out by computer, which was in agreement
with the EPMA experimental result. The ionic diffusivities and apparent activation energies were estimated, and discussed.

Key words: ionic interdiffusion, compositional distribution, piezoelectric materials, PNN/PZT system, functionally gradient materials