Large recoverable energy storage density and low sintering temperature in potassium‐sodium niobate‐based ceramics for multilayer pulsed power capacitors

Abstract

Multilayer pulsed power ceramic capacitors require that dielectric ceramics possess not only large recoverable energy storage density (W rec ) but also low sintering temperature (<950°C) for using the inexpensive metals as the electrodes.However, lead-free bulk ceramics usually show low W rec (<2 J/cm 3 ) and high sintering temperature (>1150°C), limiting their applications in multilayer pulsed power ceramic capacitors. In this work, large W rec (~4.02 J/cm 3 at 400 kV/cm) and low sintering temperature (940°C) are simultaneously achieved in 0.9 (K 0.5 Na 0.5 )NbO 3 -0.1Bi(Mg 2/3 Nb 1/3 )O 3 -1.0 mol% CuO ceramics prepared using transition liquid phase sintering. W rec of 4.02 J/cm 3 is 2-3 times as large as the reported value of other (Bi 0.5 Na 0.5 )TiO 3 and BaTiO 3 -based lead-free bulk ceramics. The results reveal that 0.9(K 0.5 Na 0.5 )NbO 3 -0.1Bi(Mg 2/3 Nb 1/3 )O 3 -1.0 mol% CuO ceramics are promising candidates for fabricating multilayer pulsed power ceramic capacitors. K E Y W O R D S(K 0.5 Na 0.5 )NbO 3 , energy storage, lead-free ceramics, transition liquid phase sintering

Lead‐free (K,Na)NbO3‐based ceramics with high optical transparency and large energy storage ability

“…However, almost all the KNN‐based ferroelectric ceramics examined in previous studies do not satisfy the requirement of both high optical transmittance and high energy storage density. Tables and show the visible optical transparency and energy storage density of most KNN‐based ceramics studied during the 2014‐2017 time period . It was found that transparent ferroelectric ceramics with high energy storage densities have rarely been created in previous studies.…”

“…The DBS depends on the grain size and porosity. A smaller grain size and the lower porosity lead to a higher DBS . In addition, relaxor ferroelectrics exhibit a higher P s and lower P r , and thus have a prominent effect on the energy storage density …”

“…6,7 In 2004, a KNN-based material was reported by Saito et al, that had a large piezoelectric coefficient of 416pC/ N. 6 This discovery triggered interest in the research of KNN-based materials. [5][6][7][8][9] Subsequent studies have investigated various aspects of these materials, including their components, 10 phase structures, crystallographic structures, domain structures, 11 electrical properties, optical transparencies, 12,13 energy storage abilities, [13][14][15] and so on. Most intriguingly, due to their high energy storage density, transparent ferroelectric materials can be applied in transparent pulsed capacitors.…”

Grain‐size–dependent dielectric properties in nanograin ferroelectrics

“…This structure leads to a very high volumetric capacitance, and the MLESCCs are suitable for surface‐mount electronics with superior mechanical and thermal properties . Therefore, MLESCCs are considered one of the most promising candidates for energy storage devices and other applications including hybrid electric vehicles and kinetic energy weapons . Generally, the dielectric layers are fabricated with ferroelectric ceramics of high dielectric permittivity, such as barium titanate (BaTiO 3 ), to achieve a high capacitance.…”

Photochromism‐induced light scattering and photoswithing in Er doped (K,Na)NbO3 transparent ceramics

“…The P max value reaches 39.2 μC/cm 2 with the electric field of 260 kV/cm, the Pr value is up to 13.4 μC/cm 2 ( Figure 7B). 32 In practical applications, the energy storage density (W) and efficiency (η) of ferroelectrics are two important factors to F I G U R E 5 A, Upconversion spectra of the KNLNB:0.01Er transparent ceramic before and after 407 nm irradiation. 31 Under a higher electric field of 260 kV/cm, the polarization intensity of the sample (0.4 mm in thickness) is to be saturated, and no dielectric breakdown appears, showing excellent electric resistance.…”