Progress and perspective of high strain NBT-based lead-free piezoceramics and multilayer actuators

Dielectric ceramics capacitors (DCC) with excellent energy storage performance (ESP) and charge-discharge performance (CDP) is very critical in the field of advanced electronics and power systems. A strategy that improves the ESP of 0.6Ba(Zr0.2Ti0.8)O3-0.4(Na0.5Bi0.5)TiO3 (BZT-NBT) ceramics was proposed via Sr2+ doping. XRD and SEM results confirmed that 0.6(Ba1-xSrx)(Zr0.2Ti0.8)O3-0.4(Na0.5Bi0.5)TiO3 (x = 0, 0.1, 0.2, 0.3, 0.4) (BSZT-NBT) ceramics formed dense and stable perovskite solid solutions. The relaxor ferroelectric (RFE) properties of BSZT-NBT ceramics were also well proved by dielectric behaviors. A large recoverable energy storage density (Wrec) and large efficiency (η) of 3.72 J cm−3 and 94.03 % (x = 0.3) can be simultaneously obtained at 289 kV cm-1. ESP of BSZT-NBT (x = 0.3) ceramics at 180 kV cm-1 exhibit good frequency (1−100 Hz) and temperature (room temperature (RT)-120 °C) stability. BSZT-NBT (x = 0.3) ceramics at 120 kV cm−1 exhibit a prominent power density (PD) and rapid discharge rate (t0.9) of of 37.62 MW cm−3 and 70.6 ns. All evidences confirm that introduction of Sr2+ into A-site of barium titanate-based ceramics could effectively improve ESP.

A-site compositional modulation in barium titanate based relaxor ceramics to achieve simultaneously high energy density and efficiency

Multi elements substituted Aurivillius phase relaxor ferroelectrics using high entropy design concept

The development of high-performance energy storage materials is decisive for meeting the miniaturization and integration requirements in advanced pulse power capacitors. In this study, we designed high-performance [(Bi0.5Na0.5)0.94Ba0.06](1-1.5x)LaxTiO3 (BNT-BT-xLa) lead-free energy storage ceramics based on their phase diagram. A strategy combining phase adjustment and domain control via doping was proposed to enhance the energy storage performance. The obtained results showed that La3+ ions doped into BNT-BT improved the crystal structure symmetry and induced a strong dielectric relaxation behavior, which destroyed the long-term ferroelectric order and effectively promoted the formation of polar nanoregions. At x = 0.12, a high recoverable energy density (Wrec) of ∼5.93 J/cm3 and a relatively large energy storage efficiency (η) of 77.6% were obtained under a high breakdown electric field of 440 kV/cm. By using a two-step sintering approach for the microstructural optimization, the energy storage performance was further improved, yielding much higher Wrec (6.69 J/cm3) and η (87.0%). Additionally, both conventionally sintered and two-step-sintered samples showed excellent frequency stability (0.5-500 Hz), thermal endurance (25-180 °C), and fatigue resistance (105 cycles). Regarding the pulse charge-discharge performance, the samples exhibited ultrashort discharge time (t0.9 ∼ 89 ns for the conventionally sintered sample and ∼75 ns for the two-step-sintered sample) under an electric field of 240 kV/cm. Furthermore, the breakdown process of the material was simulated based on the finite element analysis, and it was shown that high breakdown strength of the material could be ascribed to fine grains, which significantly hindered the crack propagation during the application of the electric field. These results show that the presented materials have great potential as high-energy storage capacitors.

High-Energy Storage Properties over a Broad Temperature Range in La-Modified BNT-Based Lead-Free Ceramics.

Phase evolution and relaxor to ferroelectric phase transition boosting ultrahigh electrostrains in (1−x)(Bi1/2Na1/2)TiO3-x(Bi1/2K1/2)TiO3 solid solutions

Ultrahigh field-induced strain in lead-free ceramics

We introduce a pit-formation method on a GaN substrate to obtain ultra-long GaN nanorods (NRs) grown homoepitaxially through hydride vapor phase epitaxy (HVPE) without an additional catalyst or a c...

Chang-Hsun Huang

Papers

Ultrahigh field-induced strain in lead-free ceramics

Achieving Ultra-long GaN Nanorod Growth by Lowering Nucleation Energy Via Surface Modification for Optical Sensors