TY - JOUR

T1 - Magnetic properties of some synthetic sub-micron magnetites.

AU - Maher, Barbara A.

PY - 1988

Y1 - 1988

N2 - The grain size dependence of various mineral (rock) magnetic parameters has been determined, using a series of essentially pure, fine-grained (single domain, SD) and ultrafine-grained (superparamagnetic, SP) magnetites. The parameters measured include low-field susceptibility, frequency-dependent susceptibility, saturation remanence (SIRM), anhysteretic susceptibility (XARM), and coercivity of remanence ((B0)CR). The magnetites were produced in experiments designed to simulate possible pedogenic and biogenic pathways of magnetite formation. Their mean grain sizes range from 0.012 um to 0.06 um, and hence span the SP/SD boundary. Isothermal magnetic measurements were performed on two separate subsets of differing packing densities. The response of the magnetic parameters is modified by interaction effects, but they display continuous variation across the entire grain size range, confirming their value for rapid magnetic granulometry. Within the fine and ultrafine end of the magnetite grain size spectrum, susceptibility, frequency dependent susceptibility and XARM are notably responsive to grain size change. In terms of magnetic response (and also possibly of grain size, shape and absence of cation substitution), these synhtetic magnetites represent close analogues of those found in some soils and sediments.

AB - The grain size dependence of various mineral (rock) magnetic parameters has been determined, using a series of essentially pure, fine-grained (single domain, SD) and ultrafine-grained (superparamagnetic, SP) magnetites. The parameters measured include low-field susceptibility, frequency-dependent susceptibility, saturation remanence (SIRM), anhysteretic susceptibility (XARM), and coercivity of remanence ((B0)CR). The magnetites were produced in experiments designed to simulate possible pedogenic and biogenic pathways of magnetite formation. Their mean grain sizes range from 0.012 um to 0.06 um, and hence span the SP/SD boundary. Isothermal magnetic measurements were performed on two separate subsets of differing packing densities. The response of the magnetic parameters is modified by interaction effects, but they display continuous variation across the entire grain size range, confirming their value for rapid magnetic granulometry. Within the fine and ultrafine end of the magnetite grain size spectrum, susceptibility, frequency dependent susceptibility and XARM are notably responsive to grain size change. In terms of magnetic response (and also possibly of grain size, shape and absence of cation substitution), these synhtetic magnetites represent close analogues of those found in some soils and sediments.

KW - magnetite

KW - environmental magnetism

KW - magnetic granulometry

KW - synthetic magnetites

KW - superparamagnetic

KW - single domain

U2 - 10.1111/j.1365-246X.1988.tb03429.x

DO - 10.1111/j.1365-246X.1988.tb03429.x

M3 - Journal article

VL - 94

SP - 83

EP - 96

JO - Geophysical Journal Royal Astronomical Society

JF - Geophysical Journal Royal Astronomical Society

SN - 0956-540X

IS - 1

ER -