Grain size dependence of properties in lead nickel niobate-lead zirconate titanate films

A chemical solution deposition procedure was developed for lead nickel niobate-lead zirconate titanate (0.3)Pb(Ni_0.33Nb_0.67) O₃-(0.7)Pb(Zr_0.45Ti_0.55O₃) ferroelectric thin films. On tailoring the heat-treatment conditions and excess lead content, the average grain diameters could be varied from 110 to 270 nm. Dielectric permittivities ranging from 1350 to 1520 and a transverse piezoelectric coefficient e_31,f as high as -9.7 C/ m² were observed for films of about 0.25 μm in thickness. The permittivity and piezoelectric response increased for samples with larger grain size. Higher thermal budgets also imposed higher levels of in-plane tensile stress on the perovskite layer; the imposed stress reduced the remanent polarization for the samples. Nonetheless, samples processed at higher temperatures showed larger average grain diameters and higher extrinsic contributions to the properties.