Structural and vibrational properties of Nd/Ca co-doped BiFeO3 synthesized by co-precipitation method

Polycrystalline samples of Bi0.9Nd0.1-xCaxFeO3 (x = 0.0 and 0.05) were synthesized using the chemical co-precipitation method to investigate the influence of Nd/Ca co-doping on structural and vibration properties. X-ray diffraction analysis confirmed the formation of a perovskite structure with good crystallinity and absence of secondary phases. A slight shift of diffraction peaks toward higher 2θ values with Ca substitution indicates lattice contraction arising from A-site ionic size mismatch. Raman spectroscopic studies revealed 13 Raman-active modes consistent with rhombohedral BiFeO3, with noticeable shifts in mode positions and intensity variations upon doping. The observed downward shifts of selected Raman modes suggest softening of lattice force constants, attributed to local structural distortion and oxygen vacancy formation. The combined XRD and Raman results demonstrate that Nd/Ca co-doping effectively modifies the local lattice environment while preserving the overall perovskite framework, providing insights into structure-property correlations in doped BiFeO3 systems.