Enhanced dielectric and piezoelectric properties in lead-free Bi0.5Na0.5TiO3–BaTiO3–SrTiO3 thin films with seed layer

0.755(Bi0.5Na0.5)TiO3–0.065BaTiO3–0.18SrTiO3 (BNT–BT–ST) thin films were deposited on the Pt(111)/Ti/SiO2/Si substrates with seed layer. Extremely enhanced electrical properties exhibited in the BNT–BT–ST film with seed layer, such as large dielectric constant (630) and piezoelectric coefficient d33 (140 pm/V) and low dielectric loss (0.032). The enhancement of electrical properties can be attributed to the seed layer, which offers nucleation site to reduce crystallization activation energy and facilitates polarization response. The seed layer also acts as a capacitive interface layer, which reduces the vacancy-type defects effectively.