Supercritical CO2-modulated defect dynamic equilibrium for magnetic-proton dual-functional CaZrO3

Abstract

In this study, fabrication of magnetic-proton dual-functional CaZrO3 via supercritical CO2 (SC CO2)-modulated dynamic defect equilibrium and multiscale lattice strain engineering has been achieved. By tuning SC CO2 pressure, a critical synergy where oxygen vacancies dynamically convert to hydroxyl groups (-OH) through proton-conductive pathways, and simultaneously pressure-induced lattice compression enhances spin polarization of O-2p orbitals. High-resolution transmission electron microscopy and X-ray diffraction reveal that 16 MPa of SC CO2 triggers defect-strain coupling, stabilizing room-temperature ferromagnetism with a saturation magnetization of 0.0865 emu/g and coercivity of 130.5 Oe, and simultaneously obtaining proton-conductive properties. Therefore, this green, dopant-free approach establishes SC CO2 as a versatile tool to regulate defect dynamics and lattice strain, bridging the gap between theoretical predictions and experimental realization of ferromagnetism in d0 oxides.