0.90(Na 0.5 Bi 0.5 TiO 3 )–0.06BaTiO 3 –0.04K 0.5 Na 0.5 NbO 3 Ferroelectric Thin Films Derived from Chemical Solutions

0.90(Na 0.5 Bi 0.5 TiO 3 )–0.06BaTiO 3 –0.04K 0.5 Na 0.5 NbO 3 (NBT–BT–KNN) polycrystalline ferroelectric thin films were prepared on Pt‐coated silicon substrates by a chemical solution deposition method. Cracks were eliminated by reducing the residual stress and single perovskite phase was realized by eliminating pyrochlore second phase when the precursor solution was modified with polyethylene glycol (PEG). The obtained NBT–BT–KNN ferroelectric thin films exhibited a large strain of 0.22% and an effective piezoelectric coefficient d 33 of 78 pm/V under the clamping of the substrate. The results indicate that the NBT‐based thin films are a potential candidate as a lead‐free piezoelectric material for microsystems.