Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The unique nonlinear dielectric properties of antiferroelectric (AFE) oxides are promising for advancements in solid state supercapacitor, actuator, and memory technologies. AFE behavior in high‐k ZrO<jats:sub>2</jats:sub> is of particular technological interest, but the origin of antiferroelectricity in ZrO<jats:sub>2</jats:sub> remains questionable. The theory of reversible electric field‐induced phase transitions between the nonpolar P4<jats:sub>2</jats:sub>/nmc tetragonal phase and the polar <jats:italic>Pca</jats:italic>2<jats:sub>1</jats:sub> orthorhombic phase is experimentally tested with local structural and electromechanical characterization of AFE ZrO<jats:sub>2</jats:sub> thin films. Piezoresponse force microscopy identifies signature evidence of a field‐induced phase transition. A significant size effect in AFE ZrO<jats:sub>2</jats:sub> is experimentally observed as film thickness is scaled down from 14.7 to 4.3 nm. The size effect is explained by modifications to the phase transition energy barrier heights ranging from 0.6 to 7.6 meV f.u<jats:sup>−1</jats:sup> depending on crystallite size and in‐plane compressive strain with decreasing ZrO<jats:sub>2</jats:sub> film thickness. Using the size effect, it is possible to double the energy storage density in ZrO<jats:sub>2</jats:sub> from 20 J cm<jats:sup>−3</jats:sup> to greater than 40 J cm<jats:sup>−3</jats:sup>, thus highlighting a feasible route for superior performance in AFE fluorite supercapacitors.</jats:p>