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Magnetic Property and Crystal Chemistry of Ilmenite (MeTiO 3 ) and Hematite (αFe 2 O 3 ) System II. Magnetic Property

1958; Physical Society of Japan; Volume: 13; Issue: 11 Linguagem: Inglês

10.1143/jpsj.13.1298

1347-4073

Yoshikazu Ishikawa, Syun-iti Akimoto,

Geomagnetism and Paleomagnetism Studies

Magnetic properties of synthesized solid solutions of ilmenite (MgTiO 3 , MnTiO 3 , FeTiO 3 , CoTiO 3 and NiTiO 3 ) and hematite (αFe 2 O 3 ) are investigated and it was confirmed that those of any ilmenite-hematite series can be divided into three parts: i) pure ilmenite, ii) solid solutions with R\bar3 crystal symmetry and iii) those with R\bar3c crystal symmetry. Pure ilmenites are antiferromagnetics having their Néel temperature below 80°K except MgTiO 3 , the Néel temperature of MnTiO 3 being determined to be 41°K. The solid solutions with R\bar3 symmetry are ferrimagnetic except MgTiO 3 series which is paramagnetic. Ferrimagnetism in FeTiO 3 , CoTiO 3 and NiTiO 3 series is due to the same mechanism, while that in MnTiO 3 series to the different one. The solid solutions with R\bar3c symmetry are again antiferromagnetics on which feeble ferromagnetism is superimposed. Through the analysis of magnetic properties of ferrimagnetic specimens, the sign of superexchange interaction with the coupling angle (\(\angle\)Me–O–Me) of 90° in the rhombohedral structure was determined.