Room-Temperature Ferroelectric LaMnO ₃ : Supercritical CO ₂ -Induced Lattice Strain and Jahn–Teller Distortion

Ferroelectric materials are regarded as core functional materials for next-generation information storage and energy-conversion devices, yet achieving stable ferroelectric performance at room temperature remains a significant challenge. In this study, supercritical CO 2 was employed to facilitate the selective incorporation of CO 2 molecules into oxygen vacancies in LaMnO 3, accompanied by partial repair of the oxygen vacancies, thereby introducing local lattice strain and structural bias. This strain propagates throughout the material via long-range elastic interactions, ultimately disrupting the global lattice symmetry and successfully stabilizing the room-temperature ferroelectric phase. Experiments demonstrate a significant positive correlation between the degree of lattice strain and the efficiency of oxygen-vacancy repair. The optimal sample exhibits excellent ferroelectric performance, with a maximum polarization intensity approximately 30 times higher than that of the original sample. Based on experimental characterization and theoretical calculations, this study reveals that structural bias modulates the local crystal field to drive noncentrosymmetric orbital ordering, which in turn induces Jahn–Teller distortion and polar structural distortion, ultimately stabilizing the ferroelectric Pmc2 1 phase. This discovery not only provides a theoretical perspective for understanding the microscopic origin of ferroelectricity in perovskite oxides but also lays a scientific foundation for designing room-temperature ferroelectric materials through chemical-incorporation strategies.