Microstructures and electrical properties of 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.2Ti0.8)O3 thin films prepared by a sol–gel route

Lead-free 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.2Ti0.8)O3 (BCZT50) thin films were deposited on (111)Pt/Ti/SiO2/Si substrates by a sol–gel route. A (Pb0.8Ca0.2)TiO3 (PCT) seed layer was introduced between film and substrate, and found to greatly influence the microstructure and electrical properties of the final BCZT50 films. The BCZT50 film grown without a seed layer showed poor crystallinity with random orientation, while the film with a seed layer was fully crystallized and exhibited high (100) orientation. The BCZT50 film with a seed layer showed enhanced electrical properties compared with of that without a seed layer, including a higher remanent polarization (6.1 μC/cm2), a larger piezoelectric constant (104 pm/V) and a lower leakage current density (J<5×10−5 A/cm2). The mechanism of enhancement of electrical properties by use of a seed layer is discussed.