Fig. 5. Crystallite size effect on H_c fitting as a function of the diameter of the mesocrystal.

a Effect of NaOAC, b Fe precursor, and c H₂O contents on the diameter and crystallite size of Fe₃O₄ mesocrystals. Red and green regions denote the regions where the crystallization pathways 1 and 2, respectively, govern the entire reaction. The solid purple line serves as a guide to the eye. Error bars indicate standard deviations. d H_c fitting depending on the diameter and crystallite size of the Fe₃O₄ mesocrystals. We expressed H_c as a function of the mesocrystal diameter for five groups with different average crystallite sizes. Error bars indicate standard deviations. The smallest mesocrystal for each group is almost a single crystal with a diameter comparable to the crystallite size. The fitted curves are represented by solid lines. e Schematic illustration of Fe₃O₄ mesocrystal as an ordered aggregate of spheres.