Open AccessEffect of Uni‐directional Pressure on Chemical Remanent Magnetization of α‐haematite
Author(s) -
Kume S.
Publication year - 1965
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1965.tb03050.x
Subject(s) - goethite , perpendicular , remanence , magnetization , magnetic field , mineralogy , field (mathematics) , materials science , orientation (vector space) , geology , condensed matter physics , chemistry , geometry , physics , mathematics , organic chemistry , adsorption , quantum mechanics , pure mathematics
Summary Goethite [α‐FeOOH] is one of the most common naturally occurring forms of iron oxyhydroxide. It dehydrates very easily on heating, changing to α‐haematite [α‐Fe 2 O 3 ]. During the change, it acquires so‐called chemical remanent magnetization (c. r. m.). In this study, the effect of uni‐directional pressures on the c. r. m. of α‐haematite produced by dehydration is investigated. A synthesized powder of goethite was heated to 300 °C under the application of unidirectional pressures up to 1500 atm in a magnetic field, the angle between the axis of pressure and the direction of the magnetic field being 65°. The direction of the c. r. m. obtained in this way was not parallel to that of the magnetic field but approached a direction perpendicular to the axis of the pressure. The angle between the direction of the c. r. m. and that of the applied magnetic field increased as the magnitude of the applied pressure increased. This deviation of the c. r. m. was explained by considering a preferred orientation of α‐haematite crystals grown under the existence of uni‐directional pressures. In the case when the same experiment was tried using a mixture of fine grain goethite and coarse grain silica sand as starting material, the above‐mentioned deviation of the c. r. m. was not observed.