Magnetic Properties of Ilmenite-Hematite System at Low Temperature

The magnetic properties of FeTiO 3 containing less than 50 mole percent of Fe 2 O 3 have been re-examined between 2°K and room temperature by means of a Cioffi-type automatic fluxmeter. It was confirmed that each specimen has a low-temperature transition point, which decreases in temperature with increasing content of Fe 2 O 3 . Above the transition temperature the specimens with 8 and 12 mole % Fe 2 O 3 show superparamagnetic behavior. By analysis of the superparamagnetic magnetization curves, the sizes of the superparamagnetic clusters were determined. The average size of clusters in these crystals is found to be explained by a simple assumption that one Fe 3+ ion which enters into the Ti layers of ilmenite alignes the spins of 9 nearest neighbour Fe ions parallel by a superexchange interaction. The complete phase diagram of the ilmenite rich side of the solid solution, as revised by the present study, is presented.