Polar-nonpolar phase competition of ferroelectric materials under coupled shock pressure and self-generated electric field

Ferroelectric materials have attracted significant attention due to their excellent piezoelectric, pyroelectric, and ferroelectric properties. In applications where ferroelectric ceramics are subjected to coupled shock pressure-self-generated electric field environments, their phase structures critically determine device performance and application scope. However, studies on ferroelectric phase transitions under pressure-electric field coupling remain limited, and the lack of phase diagrams under field conditions hinders the development and application of ferroelectrics in complex environments. In this work, we investigate the discharge behavior of $\mathrm{KNb}{\mathrm{O}}_{3}$ ceramics under coupled shock pressure and self-generated electric field conditions, and reveal the competition between polar and nonpolar phases. By analyzing the relationship between shock-induced electrical responses and phase transitions, the phase evolution under pressure-electric coupling field is clarified. Combined with first-principles density functional theory calculations, a phase diagram of ${\mathrm{KNbO}}_{3}$ undercoupled pressure and electric fields is constructed. These findings provide crucial insights into phase transition mechanisms under coupled fields and offer valuable guidance for the design and optimization of ferroelectric materials and devices.