Sn and Ce co-doping regulate phase structure of NaNbO ₃: Double hysteresis loop and electro-strain

Environmentally friendly antiferroelectric NaNbO₃ (NN) materials exhibit promising potential in energy storage and electro-strain applications. At room temperature, NN is antiferroelectric P phase (Space group Pbma) coexist with metastable ferroelectric Q phase (Space group P2₁ma), so the electric field-induced phase transition is irreversible. To stably the intrinsic antiferroelectric properties of NN, phase structure regulate has emerged as a critical research focus. We chose the variable-valence elements Sn and Ce for doping in NN. Through atmospheric sintering, the valence states of the doped ions were altered, resulting in changes to their corresponding substitution positions. This confirmed that the doped ions could successfully incorporate into the lattice as designed. Of particular importance is that <em>x</em> = 0.04 ceramic exhibited reversible phase transition between the AFE and FE states, showing a standard double hysteresis loop at room temperature, achieving a large electro-strain of 0.38 %. These findings demonstrate that valence state-controlled co-doping effectively optimizes the antiferroelectric phase stability and functional performance of NN-based materials.