Achieving high energy storage performance by LaMg0.5Ti0.5O3 modification of multiphase engineered Bi0.5Na0.5TiO3–based ceramics

Abstract

High performance lead–free ceramic capacitors are a key factor in the practical application of new pulsed power systems, which require higher energy storage density, energy efficiency, and the ability to operate stably in extreme environments. Therefore, this paper proposes a strategy for multiphase engineering of induced polar nanoregions (PNRs) and the design of (1-x)(0.94Bi0.5Na0.5TiO3–0.06BaTiO3)–xLaMg0.5Ti0.5O3 lead–free ceramics. The content of the tetragonal (T) and rhombohedral (R) phases is controlled by adjusting the content of LaMg0.5Ti0.5O3 to enhance the energy storage properties of the ceramics. The introduction of the broadband oxide MgO and the rare earth ion La3+ optimizes the grain size of the ceramics to achieve higher breakdown strengths, which can be confirmed in the first principles calculations. The higher breakdown strength leads to a larger saturation polarization further resulting in a higher recoverable energy density. The introduction of these dopants causes structural disorder, resulting in enhancement of the relaxation properties and a thin P–E loop, thus achieving an extremely high recoverable energy density (3.72 J/cm3) and energy efficiency (82.3%). At the same time, the ceramic has a high temperature stability (η varies less than 3.9%) and frequency stability (η varies less than 3.7%). All of the above work shows that the design has great potential for application in the field of pulsed capacitors.