Zhengbo Shen

BaTiO3–BiYbO3 perovskite materials for energy storage applications

Novel perovskite-type (1 − x)BaTiO3–xBiYbO3 solid solutions with x = 0.00–0.20 were synthesized using conventional solid-state reaction methods. A systematic structural change from ferroelectric tetragonal to pseudo-cubic phase was observed at about x = 0.050–0.051 at room temperature. Dielectric measurements revealed a gradual change from normal ferroelectric behavior to highly diffusive and dispersive relaxor-like characteristics, wherein the phase transition temperature shifted to a higher temperature with increasing frequency. With an increase in the BiYbO3 content, the nonlinearity of the (1 − x)BaTiO3–xBiYbO3 ceramic was weakened obviously. The bulk ceramics were characterized by high polarization maxima and low remnant polarization, which exhibit slim P–E hysteresis loops. The results demonstrate that the (1 − x)BaTiO3–xBiYbO3 ceramics are promising lead-free relaxor materials for energy storage applications.

Core-satellite BaTiO3@SrTiO3 assemblies for a local compositionally graded relaxor ferroelectric capacitor with enhanced energy storage density and high energy efficiency

Dielectric capacitors with high energy density and low energy loss are of great importance in high power electric and electronic systems. Traditional BaTiO3 (BT) or its solid solutions have been widely explored as high energy density materials owing to their notably high dielectric constants. However, these materials often suffer from significant drawbacks of strong dielectric nonlinearity, low breakdown strength and high hysteresis loss, limiting the energy storage density and energy utilization efficiency. In this study, by using core-satellite structured nanocubic SrTiO3 (ST) decorated BT assemblies, a composite capacitor with enhanced breakdown strength and weaker dielectric nonlinearity was successfully fabricated in contrast with the pure ferroelectric BT ceramic, resulting in elevated energy storage density and high energy efficiency as extracted from the polarization-electric field loops. The mechanism behind the improved electric and dielectric performances was discovered to be the remarkable suppression of grain size owing to the existence of the ST nanocubes and also the ferroelectric relaxor behaviors arising from the local compositionally graded structure due to the controlled sintering and modulated diffusion of Sr. This work provided a new approach for fabrication of dielectric materials with promising high energy density and low loss.

Dielectric Enhancement in Graphene/Barium Titanate Nanocomposites

GN/BT nanocomposites were fabricated via colloidal processing methods, and ceramics were sintered through two-step sintering methods. The microstructure and morphology were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. XRD analysis shows that all samples are perovskite phases, and the lattice parameters a and c almost decrease linearly with the increase of graphene nanosheets. The dielectric properties were tested by using precision impedance. The maximum dielectric constant at the Curie temperature for the nanocomposites with graphene addition of 3 wt % is about 16,000, almost 2 times more than that of pure BaTiO3 ceramics. The relaxation, band structure, density of states, and charge density distribution of GN/BT superlattices were calculated using first-principles calculations for the first time, and results showed the strong hybrid interactions between C 2p states and O 2p and Ti 3d orbitals.

Correction: BaTiO3–BiYbO3 perovskite materials for energy storage applications

Correction for ‘BaTiO3–BiYbO3 perovskite materials for energy storage applications’ by Zhengbo Shen et al., J. Mater. Chem. A, 2015, 3, 18146–18153.