Crystal Facet Engineering of YFeO3 via Hydrothermal Growth Regulation: Synergistic Effects of Surface Structure Evolution and Oxygen Vacancies on Magnetic Properties

The manipulation of crystal facets and oxygen vacancies provides an effective strategy for tuning the magnetic properties of functional perovskite oxides. However, the synergistic relationship between facet evolution, oxygen vacancy concentration, and magnetic behavior remains insufficiently understood. Herein, a polyvinylpyrrolidone (PVP)-assisted hydrothermal strategy was developed to regulate the crystal facets of orthorhombic YFeO3 through controlled growth processes. The effects of mineralizer species (KOH and NaOH) and PVP content on facet evolution, oxygen vacancy concentration, and magnetic properties were systematically investigated. XRD results demonstrate that hydrothermal regulation effectively modifies the texture coefficients of specific crystal facets while maintaining the orthorhombic perovskite structure. KOH induces stronger anisotropic growth than NaOH, while PVP promotes the formation of well-defined polyhedral crystals by regulating facet growth. XPS analysis reveals that facet regulation is accompanied by variations in surface oxygen vacancy concentration. The optimized YFeO3 crystals exhibit tailored magnetic properties, with a maximum remanent magnetization of 0.81 emu·g–1, arising from the cooperative modulation of facet-dependent structural evolution and oxygen vacancies on spin canting and magnetic anisotropy. This work provides insights into facet–defect engineering for designing magnetic perovskite oxides.