To date, several portable, wearable, and even implantable electronics have been incorporated into ultracompact devices as miniaturized energy-autonomous systems (MEASs). Electrostatic supercapacitors could be a promising energy storage component for MEASs due to their high power density and ultrashort charging time. Several dielectric materials, including ceramics, polymers, and glass, have been studied for energy storage applications. However, due to their large thickness (in micrometers or larger), these materials are inappropriate for use as nanocapacitors. Recently, ferroelectric and antiferroelectric fluorite-structured dielectrics (e.g., zirconia and hafnia) have been studied intensively for data storage and energy-related applications. Their nanoscale (nm) thickness makes these materials suitable for use as nanocapacitors in MEASs. This work reviews the energy storage properties of fluorite-structured antiferroelectric oxides (HfO2 and ZrO2), along with 3-D device structures, the effect of negative capacitance on the energy storage characteristics of fluorites, and the future prospects of this research field.

Ferroelectric (FE) and antiferroelectric (AFE) materials are used for several memory-related and energy-related applications. Perovskite materials (e.g., bulk ceramics) remain the most common materials for many applications. However, due to large deposition thickness, these materials are not appropriate for future miniaturized devices. In 2011, FE and AFE properties were reported in Si-doped HfO 2 thin films. HfO 2 -based FE and AFE materials have several advantages over conventional materials, such as ultrathin deposition thickness (in range of nanometers), compatibility with existing Si semiconductor technology, and suitability for the integration within 3-D nanostructures. Therefore, fluorite-structured materials can be appropriate for miniaturized devices. These fluorite-structured materials are extensively studied for memory and energy-related applications. The first review on this topic was published after four years of discovering the FE and AFE properties in these materials. From the past decade, a lot of research has been reported about the detailed mechanism and application of these materials. This review insightfully discusses the progress in the research of fluorite-structured materials and critically discusses some potential applications. Here some challenges are also discussed, new knowledge is extracted, and promising future research directions of these materials are suggested.

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