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

In this work, by doping the B-site of BaTiO 3 with Mg elements, we have prepared BaMg x Ti 1- x O 3- x (BM x T) films with superparaelectric behaviors. The microstructures, polarization behaviors, breakdown strength, leakage current density, and energy storage performance are investigated systematically of the BM x T 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/cm 3 ) 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.