Strain Engineering of Energy Storage Performance in Relaxor Ferroelectric Thin Film Capacitors

Abstract

Dielectric energy storage capacitors are receiving a great deal of attention owing to their high energy density and fast charging-discharging speed. The current energy storage density of dielectrics is relatively low and cannot meet the requirements of miniaturization of pulsed power equipment. Therefore, increasing the energy storage density of dielectrics has become a research hotspot. Herein, using phase-field simulations to design polymorphic nanodomains, the strain engineering of energy storage performance of binary and ternary solid solution relaxor ferroelectric films is investigated. The results show that the energy storage performance of the ternary film is better than that of the binary film due to the polymorphic nanodomains. In addition, as the film in-plane strain is modified from −2% to 2%, the energy density is improved by 80%, and the efficiency also increases from 52% to 77%. This work proves the remarkable energy storage performance of polymorphic films and provides a theoretical basis to optimize the energy-storage performance of ferroelectric thin-film capacitors by adjusting the misfit strain.

Enhancing the Elastocaloric Strength by Combining Positive and Negative Elastocaloric Effects

“…Landau–Devonshire theory is widely used to study the caloric effect of monocrystalline ferroelectric materials. [ 45–49 ] From Liu et al's article, the total thermodynamic free energy density consists of the Landau energy density and the elastic energy density. [ 23 ] And we just consider the stress applied in the Z direction ( σ 1 = σ 2 = σ 4 = σ 5 = σ 6 = 0, σ 3 ≠ 0), so the final free energy density expression is…”

“…Landau-Devonshire theory is widely used to study the caloric effect of monocrystalline ferroelectric materials. [45][46][47][48][49] From Liu et al's article, the total thermodynamic free energy density consists of the Landau energy density and the elastic energy density. [23] And we just consider the stress applied in the Z direction (σ 1 ¼ σ 2 ¼ σ 4 ¼ σ 5 ¼ σ 6 ¼ 0, σ 3 6 ¼ 0), so the final free energy density expression is…”

Antiferroelectric Phase Diagram Enhancing Energy-Storage Performance by Phase-Field Simulations

“…Compared with other energy-storage devices, such as batteries and electrochemical capacitors, dielectric capacitors have the advantages of fast charging/discharging speed and high power density. − The energy is stored via electric polarization in the form of the electrostatic field. The centers of positive and negative charges do not coincide under the external electric field, which results in polarization.…”

Strain-Tuning Bloch- and Néel-Type Magnetic Skyrmions: A Phase-Field Simulation

“…In the phase-field model [33][34][35][36][37], the spatial distribution of the magnetization field M = Msm = Ms(m1, m2, m3) is used to describe the domain structure, where Ms and m are the saturation magnetization and the components of unit magnetization vector, respectively. The transient magnetization domain structure is described by the Landau-Lifshitz-Gilbert (LLG) equation:…”

“…The simulation in this work uses FeGa alloy and Co20Fe60B20 as model systems to study the strain effect on the magnetic domains with different domain walls types. The materials parameters for ultrathin Co20Fe60B20 used in simulations are listed as follows [24,[35][36][37][38]: Aex = 1.9 × 10 -11 J/m, K1 = 196 GPa, c12 = 156 GPa. In the present simulations, the elastic stiffness tensor for the ferroelectric substrate is set as the same as that of the magnetic island, i.e., cp = cisland for simplicity.…”