To investigate the effect of Ca 2+ doping on the local states of Fe ions in NdFeO 3 , a series of Nd 1-x Ca x FeO 3 (x = 0-0.4) samples were synthesized using the sol-gel method and characterized by XRD, Mossbauer spectroscopy, and VSM. The results indicate that with increasing Ca 2+ doping content, the degree of lattice distortion in the orthorhombic system decreases, and the crystal symmetry of the samples improves. Mossbauer spectroscopic analysis reveals that as the doping content increases, the hematite phase content in the samples gradually rises; concurrently, the characteristic doublet signal of Fe 4+ becomes increasingly pronounced with higher doping levels, indicating the progressive formation of a mixed Fe 3+ /Fe 4+ valence state in the system. Magnetic measurements reveal a significant reduction in remanent magnetization and coercivity, which is highly consistent with the increase in the hematite phase, the weakening of magnetic ordering, and the enhancement of magnetic exchange inhomogeneity observed in the Mossbauer spectroscopic analysis. This study elucidates how Ca 2+ doping regulates the local states of Fe ions through the synergistic effects of charge compensation and structural distortion, providing important spectroscopic evidence and a material foundation for the magnetic analysis of perovskite-type ferrites.
Du et al. (2026) studied this question.