Hysteresis properties of titanomagnetites: Grain-size and compositional dependence
Abstract
Sized fractions of x = 0.6, 0.4, 0.2 and 0.0 titanomagnetites were studied with a vibration magnetometer. In the course particles ( d > 150 μm), no compositional dependence of hysteresis parameters was found. HC was less than 50 Oe, HR/ HC > 4 and JR/ JS < 10 -2, reflecting multi-domain behaviour. In contrast, fine particles ( d ⋍ 0.1 μ m) revealed systematic grain-size dependence of parameters with coercive force as high as 2,000 Oe in x = 0.6 titanomagnetite. Grain-size dependence studies revealed broad transition sizes for the onset of true multi-domain behaviour depending upon which factor is chosen. In magnetite it varies from 10 to 20 μm. The experimental critical size for single-domain behaviour for magnetite is about 0.1 μm and for x = 0.6 titanomagnetite 1-2 μm.
- Publication:
-
Physics of the Earth and Planetary Interiors
- Pub Date:
- January 1977
- DOI:
- 10.1016/0031-9201(77)90108-X
- Bibcode:
- 1977PEPI...13..260D