Microstructures and electrical properties of 0.5(Ba_0.7Ca _0.3)TiO₃-0.5Ba(Zr_0.2Ti_0.8)O ₃ thin films prepared by a sol-gel route

Lead-free 0.5(Ba_0.7Ca_0.3)TiO₃-0. 5Ba(Zr_0.2Ti_0.8)O₃ (BCZT50) thin films were deposited on (111)Pt/Ti/SiO₂/Si substrates by a sol-gel route. A (Pb_0.8Ca_0.2)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.