抄録
The thermo-remanent magnetism and the coercive force of the ilmenite-hematite solid solution (1-x) Fe2O3·xFeTiO3 have been examined for the range 0<x<0.7: in the range x>0.7, the solid solution is only paramagnetic at room temperature. The specimens are all synthesized ones. Measured quantities are J(T), Jr(T), Hc(T) and Hcr(T) for the maximum field of 800Oe. and the TRM [JT0Tc, H=2.0 oe.(T)]. The summarized results are as follows: In the parasitically ferromagnetic region (x<0.5), J(T) and Jr(T) show an increase below the Curie point, while Hc(T), and Hcr(T) decrease monotonously with temperature. Thermoremanent magnetism is strong in comparison with J(T) in this region, the Q-ratio amounting to several hundred. In the ferrimagnetic region (0.7>x>0.5), J(T) and Jr(T) show the typical straight decrease with temperature rise. Hc and the Q-ratio are quite smaller than for the parasitically ferromagnetic region. Remarkable reverse TRM like the Haruna-type one appears for the specimens of the range bordering the ferrimagnetic and parasitically ferromagnetic regions, namely the range 0.6>x>0.45. This indicates that the phenomenon is inherent to this substance and is closely related to the fundamental magnetic properties of this series. Furthermore, it was found that a definite tendency for reverse TRM appears for x≈0.1 that may be relevant to the natural reverse remanence of Adirondack rocks reported by Balsley and Buddington. Stability against the AC demagnetization and the field dependence of the thermo-remanent magnetism of this series have also been examined systematically.
