Pressure-Driven Explosive Energy Conversion in Lead-Free Ferroelectric (Ag,K)NbO3

Abstract

Designing the giant-performance explosive energy conversion of lead-free ferroelectrics attracts increasing attention from the medical, energy, defense, and mining industries, whereas the underlying physics mechanism remains ambiguous. Here, chemical modification and pressure engineering are utilized to induce a structural competition between polar and nonpolar structures to achieve a superior explosive energy conversion ($34.57\phantom{\rule{0.2em}{0ex}}\mathrm{J}/{\mathrm{cm}}^{3}$) from lead-free (${\mathrm{Ag}}_{0.935}{\mathrm{K}}_{0.065}){\mathrm{Nb}\mathrm{O}}_{3}$ ceramics, enabling a sharp mechanical-stimulating pulse current within microseconds and having excellent thermal stability of phase structure. We reveal that these merits are related to a local structural heterogeneity on the atomic length scale. Pressure-regulating ferroelectric-antiferroelectric order is responsible for its explosive energy conversion, in which the evolution of oxygen octahedron distortion and electronic transition dynamics under the stress field have been specified. This work reveals the physical origin of the excellent energy-conversion performance of $(\mathrm{Ag},\mathrm{K}){\mathrm{Nb}\mathrm{O}}_{3}$, and draws a clear scenario for developing the advanced lead-free ferroelectrics device with high-performance energy conversion.