Effect of Incomplete Reaction on the Structure and Magnetic Properties of YMn0.5Fe0.5O ₃

This study investigates the phase evolution and magnetic properties of YMn[Formula: see text]Fe[Formula: see text]O 3 near its morphotropic phase boundary, with a specific focus on the role of reaction kinetics modified by pre-sintering compaction. Experimental results indicate that eliminating macroscopic voids via pellet-pressing facilitates a more complete solid-state reaction. This process drives a partial structural transition from a metastable, geometrically frustrated layered hexagonal phase ([Formula: see text][Formula: see text]cm) to a three-dimensional orthorhombic phase (Pnma). [Formula: see text]Fe Mössbauer spectroscopy reveals that the enhanced structural dimensionality allows iron ions to overcome the magnetic frustration associated with the initial large quadrupole splitting (1.20[Formula: see text]mm/s), establishing a robust G-type antiferromagnetic order. Furthermore, macroscopic magnetic measurements demonstrate that the transition to the orthorhombic phase is accompanied by the emergence of weak ferromagnetism. This magnetic behavior originates from the cooperative tilting of MO 6 octahedra, which breaks local inversion symmetry and activates the antisymmetric Dzyaloshinskii–Moriya (D–M) interaction. Consequently, optimizing solid-state reaction conditions proves essential for tuning the spin-lattice coupling and magnetic ground states in complex multiferroic solid solutions.