Non-Equilibrium Solidification of KNN-Based Glass-Ceramics via Aerodynamic Levitation for Enhanced Dielectric Propertiles

초록

The increasing demand for energy-efficient materials in next-generation capacitors and power storage devices has driven research into high-performance ferroelectrics. Among them, (K,Na)NbO₃ (KNN)-based materials, which are solid solutions of KNbO₃ and NaNbO₃, have attracted significant attention due to their high dielectric constant and large recoverable energy density. However, conventional fabrication methods often suffer from uncontrolled crystallization, leading to inhomogeneous phase distributions and limiting material performance. In this study, we employ aerodynamic levitation (ADL) processing to overcome these limitations and stabilize a highly uniform microstructure. By precisely controlling the solid solution composition of KNbO₃ and NaNbO₃, we synthesize morphotropic phase boundary (MPB) compositions, where the coexistence of multiple ferroelectric phases enhances dielectric and polarization properties. The ADL process allows for non-equilibrium solidification, preventing heterogeneous nucleation and promoting a well-distributed domain structure. Our findings demonstrate that mixing KNbO₃ and NaNbO₃ near the MPB composition leads to a maximized random domain effect, which significantly improves dielectric tunability, breakdown strength, and polarization response. The stabilization of metastable phases via levitation-based processing provides a novel route for designing high-performance KNN-based ferroelectric materials, paving the way for advanced capacitor technologies and dielectric applications.