High energy storage performance in Mg modified BaTiO3 films with superparaelectric behavior

In this work, by doping the B-site of BaTiO3 with Mg elements, we have prepared BaMgxTi1-xO3-x(BMxT) films with superparaelectric behaviors. The microstructures, polarization behaviors, breakdown strength, leakage current density, and energy storage performance are investigated systematically of the BMxT films. The breakdown strength of the film reaches 7.5 MV/cm when x = 0.18, at the same time, excellent energy storage density (67.7 J/cm3) and energy storage efficiency (94.9 %) are obtained, which is attributed to the doping of the acceptor element Mg. By doping Mg with a lower chemical valence state to form defect dipoles in the lattice, the breakdown strength and polarization properties of the film are improved while reducing the crystallinity of the film, forming a hysteresis loop with superparaelectric properties. This work provides a feasible route to design superparaelectric materials with simple compositions for high-performance capacitive energy-storage.