Energy storage and polarization switching kinetics of (001)-oriented Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thick films

Abstract

For antiferroelectric (AFE) energy storage, the stability of energy storage density and conversion efficiency against wide temperature (T) range and broad frequency (f) band is highly preferred. In this work, we investigate the energy storage and associated kinetics of polarization switching in (001)-textured AFE Pb0.97La0.02(Zr0.95Ti0.05)O3 (PLZT 2/95/5) thick films prepared by sol-gel method. A recoverable energy storage density (Wre) of ∼26.8 J/cm3 and an energy conversion efficiency (η) as high as ∼62.5% have been obtained under an electric field of 1.85 MV/cm and room temperature. Both the Wre and η are only weakly T-dependent up to 280 °C and weakly f-dependent ranging from 20 Hz to 10 kHz. The high frequency stability originates from the rapid polarization switching as identified by the nucleation-limited-switching theory, suggesting a characteristic switching time as short as ∼3 ns, favorable for applications in pulse energy storage.

Enhanced energy density with a wide thermal stability in epitaxial Pb0.92La0.08Zr0.52Ti0.48O3 thin films

“…This behavior is similar to the PLZT (4/98/2) and PLZT (2/95/5), expect the relative higher g due to reduced defects through epitaxy. 9,21 In contrast, the W rec fluctuates between 11.6 J/cm 3 and 10.6 J/cm 3 , which demonstrates that the W rec is weakly frequency-dependent. The data measured in the test temperature range (25 C-180 C) exhibit similar behaviors.…”

“…[1][2][3][4] Among the electrical energy storage devices, dielectric capacitors have attracted much attention due to their applications in decoupling and DC-link capacitors, AC/DC converters, and portable power electronics for the advantages of high operation voltage, high power density, and low weight and volume. [4][5][6][7] For a dielectric capacitor, high dielectric constant, high breakdown electric field, as well as low remnant polarization are desired for achieving high recoverable energy density W rec and energy conversion efficiency g. 8,9 Although high-k dielectric oxide films exhibit high breakdown strength of 3-12 MV/cm and almost fully recoverable energy efficiency, 6 the relatively low dielectric constant on the order of ten leads to a moderate recoverable energy density around 1-2 J/cm 3 . 7 Ferroelectrics are promising for higher energy density than linear dielectrics, since their dielectric constant is larger than that of the linear dielectrics by one or two order in magnitude.…”

“…However, the W rec of the Pb-based antiferroelectric thin film is usually less than $20 J/cm 3 , because of the low breakdown strength in a wide temperature range. 9,22,23 The need for increased W rec and g in a wide temperature range has motivated the efforts of exploring relaxor ferroelectric materials, a subclass of ferroelectrics. The domain sizes of relaxor ferroelectrics are on order of nanometers instead of micrometers like those of typical ferroelectric materials, leading to smaller coercive field and lower remnant polarization in the typical P-E loop.…”

“…Polycrystalline Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 (PLZT) relaxor ferroelectric film (1-3 lm) exhibits a good thermal stability of energy density ($22 J/cm 3 ) from room temperature to 200 C. 8 However, the polycrystalline film quality limits its breakdown strength, and hence induce a low W rec . 9 In the polycrystalline film, there are many defects, grain boundaries, crystal orientations or fine pores, which not only assist in electron penetrating the film, but also influence its thermostability due to the defects that are a)…”

“…From the microstructure analysis (Figure 1), there are no grain boundaries, porosity in the epitaxial film, which prevents the electric tree from penetrating the film by grain boundaries or porosity and thus increases the breakdown strength. 9,29 To investigate the thermal stability of epitaxial PLZT thin films, the temperature-dependent P-E loops at the fixed E max ¼ 2.27 MV/cm are measured and shown in Figure 3(a). Both the maximum polarization P max (black) and the remnant polarization P r (red) increase as the operating temperature increase (Figure 3(b)).…”