Regulating the field-induced AFE-FE transition in NaNbO3 from the perspective of powder surface energy

Sodium niobate (NaNbO₃, NN) has drawn growing attention for its wide application in engineering fields due to the room-temperature antiferroelectric phase with an orthorhombic Pbcm space group, which is generally known as the P phase. However, a ferroelectric Q phase is commonly induced out of P phase under the applied electric field leading to a coexistence of these two phases. Accordingly, this irreversible transition reported in previous literature causes the unobservable double polarization hysteresis loops of NN at ambient conditions. Thus, it has significant implications in investigating the formation of ferroelectric or antiferroelectric phase and the corresponding field-induced transition. Herein, the content ratio of P/Q phase in polycrystalline NN ceramics is effectively regulated from the perspective of powder surface energy, through adjusting the ball-milling time during solid-state reaction process. Moreover, the physical mechanism of field-induced transition is explored based on analyzing the room-temperature ferroelectric properties and the in situ Raman spectra with varying electric field. This work provides feasible strategy of modulating the inversion between ferroelectric and antiferroelectric phases in NN. The analysis of theoretical results can facilitate further design of NN-based materials for actual application in technologies.