Pour an aqueous solution of iron chloride and barium chloride into an aqueous solution of sodium hydroxide and sodium carbonate, and a reddish-brown precipitate forms. This precipitate is not BaFe12O19 but a precursor: a mixture of hydrous iron oxide (often written Fe(OH)3) and BaCO3. Only after you make the solutions in ①, precipitate in ②, wash, filter, and dry in ③, and calcine in ④ do you obtain the target magnetic material. In ⑤ you press, sinter, and magnetize it, and measure its strength as a magnet (apparent remanent magnetization) with a balance. Every step takes over the sample from the previous step as it is, so you can follow how a change of conditions alters the later results.
Mochizuki Research Group, Tokyo University of Science. The procedure and conditions (reagent masses and water volumes, pouring direction, decantation washing with warm water at about 60 °C, filter paper 5B, drying at 105 °C for about 20 h, calcination at 925 °C for 2 h, and the pressing, sintering, and magnetization conditions) follow the 2025 edition of the lab manual for Materials Science Experiments (Inorganic Materials) of the former Tokyo Institute of Technology (§8.1–8.5) and the practical-session videos (A1–A3, B1–B4). The heat-treatment atmosphere (air) and the balance dimensions (thickness of the reference magnet 14.020 mm, distance to the sample stage 37.349 mm) are as instructed by Prof. Mochizuki (2026-09-25). The standing time, pouring rate, density of the sintered body, and similar values are provisional. The aqueous equilibria are calculated from charge balance and solubility products. The rates of washing, filtration, drying, calcination, and sintering, and the magnetic properties, come from schematic models built on estimates chosen for teaching; they are not predictions of measured values. Detailed explanations and sources are on the explanation page (in Japanese). Back to: Mochizuki Research Group Education — Inorganic Materials Science > Virtual Experiments, Inorganic Materials Science resources