Structural and Magnetic Transitions in Bi0.9La0.1FeO3: The role of Post-Synthesis Annealing

The effect of annealing temperature on the structure and magnetic properties of Bi0.9La0.1FeO3 prepared by the sol–gel method was investigated. X-ray diffraction results showed that all samples primarily crystallize in the rhombohedral R3c phase, while lower annealing temperatures reduce the average crystallite size and cause a small increase in the cubic Pm3m contribution. Mössbauer spectroscopy indicated that the cycloidal magnetic component is more pronounced in the spectra for samples annealed at higher temperatures, whereas the lowest-temperature sample shows stronger size-related effects. Magnetic measurements confirmed an increase in magnetization as the annealing temperature decreased. These results show that post-synthesis annealing is an important factor for controlling the structural and magnetic behavior of La-doped BiFeO3.