Abstract
The magnetite obtained by simultanious precipitaton from the mixed solution of ferrous and ferric ion (1:2) does not show the magnetic transformation at low temperature, and it can be easily oxidized in air.
It is supposed that the solid-solution of magnetite-γ-hematite is formed by oxidation of precipitates in air, and when this solid-solution was heated in neutral atmosphere, it changes to the magnetite having the magnetic transfomation at low temperature and α-hematite.
This segregation temperature is varied by the precipitating time and temperature. On the other hand, the precipitate changes to γ-hematite by low temperature heating in air. The transition point from this γ-hematite to α-hematite is also varied by precipitating time and temperature.
