Relationship between median destructive field and remanent coercive forces for dispersed natural magnetite, titanomagnetite and hematite |
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| Authors: | Peter Dankers |
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| Institution: | Paleomagnetisch Laboratorium 'Fort Hoofddijk', Budapestlaan 17, Utrecht, The Netherlands |
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| Abstract: | Summary. Remanent acquisition curves, remanent hysteresis curves and alternating field demagnetization curves were determined for a number of artificial rock specimens containing well-defined grain-size fractions between 5 and 250 μm of natural magnetite, titanomagnetite and hematite. From these curves, the remanent acquisition coercive force H 'cr, the remanent coercive force H cr and the median destructive field of IRM H ½I were determined. Theoretically these parameters should be the same for an assembly of non-interacting, homogeneously distributed, randomly oriented single-domain grains. For a given hematite specimen H 'cr, H cr and H ½I have about the same value in spite of the strong grain-size dependence of these parameters. For each specimen of magnetite and titanomagnetite the value of H 'cr is larger than H cr which again is larger than H ½I. However, the ratios H 'cr/ H cr and H ½I/ H cr appear to have a (different) constant value. An interesting relationship which appears to hold for dispersed magnetite, titanomagnetite or hematite grains between 5 and 250 μm, independently of grain-size, quantity and packing density of the magnetic material, is:  |
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