Influence of Pb and La Contents on the Lattice Configuration of La-Substituted Pb(Zr0.65, Ti0.35)O3 Films

The systematic investigation of the influence of Pb and La contents on the lattice configuration in La-substituted Pb(Zr_0.65,Ti_0.35)O₃ (La-PZT) films was carried out. La-PZT films with various La and Pb contents were fabricated on Pt/Ti/SiO₂/Si substrates by chemical solution deposition (CSD). In the La-PZT films with a Pb content ratio of 125% relative to a stoichiometric value, La ions were substituted for not only A-site ions but also B-site ions at La contents over 3 mol%. La substitution for B-site seems to cause larger reduction of the unit cell size. In addition, we found that in the La-PZT films with a La content of 3 mol%, the Pb content of 116 mol% (120% relative to a stoichiometric value) was optimum from the view point of site occupancy. This suggests that excess Pb prevented the A-site substitution of La ions.