Enhanced energy storage properties of BaTiO3 thin films by Ba0.4Sr0.6TiO3 layers modulation

Electrostatic dielectric energy storage capacitors have attracted much attention recently for their fast charging-discharging speed and high power density. Trilayered Ba0.4Sr0.6TiO3/BaTiO3/Ba0.4Sr0.6TiO3 (BST/BT/BST) thin films were prepared by spin-coating technique. The sandwich-structured thin films showed high dielectric constant (εr = 952) and low dielectric loss (tanδ = 0.034) at room temperature (10 kHz). Moreover, the dielectric constant of the thin films demonstrated good frequency stability within the measured frequency range and broad capacitance variation (20 °C-160 °C, ΔC/C25°C<±10%). The electric-field dependence of dielectric response was investigated and the dielectric tunability was 13.3% at 100 kV/cm. Compared with pure BT thin films, the heterostructure exhibited enhanced electric breakdown strength and energy storage density. The recoverable energy storage density and efficiency of BST/BT/BST thin films were 14.69 J/cm3 and 33.9% at 1.44 MV/cm, respectively. The results indicated that BST/BT/BST heterostructure films would be an alternative way to improve the energy storage density of dielectrics for applications.