Diamagnetic Orientation of Clay Mineral Grains

Efficiency of Magnetic Alignment Found in Various Paramagnetic and Diamagnetic Solids Detected by Simple Rotational Oscillation of Sample in Microgravity

“…1(b). 3,4,6) Á was obtained from a period of oscillation with negligible contribution of D and l as,…”

“…3,4) Small amount of preferential orientation of individual bond direction with respect to a magnetic principle axis of the crystal cause the resultant diamagnetic anisotropy of a crystal. Calculated ðÁÞ DIA value of a crystal using this model was consistent with the measured value for popular oxides, namely for corundum, KDP, gypsum, orthoclase, -quartz, Mg(OH) 2 [6][7][8] Here magnetically unstable axis was parallel to bond direction; the assignment was compatible with the fact that spatial electron distribution is spread preferentially in directions perpendicular to a bond direction.…”

“…Hence it was difficult to perform quantitative analysis on alignment process for most of the materials. Alignment of micron-sized particles dispersed in fluid were quantitatively studied on inorganic material such as clay and mica minerals based on reliable Á values; 3,4) it was explicitly shown that alignment was controlled by magnetic anisotropy per unit mass Á, temperature T and mass of particle M. The above-mentioned fact is directly deduced from a conventional mechanism proposed by Langevin and Curie.…”

“…Hence sensitivity was limited by physical properties of the fiber. The torque of fiber was controlled to be negligible by introducing a thin fiber; 3,4) accumulation of small Á proceeded for various oxides with a detection limit of 1  10 À9 emu/g. 5,6) Á of a material is described by a sum of diamagnetic anisotropy ðÁÞ DIA and paramagnetic anisotropy ðÁÞ PARA .…”

“…Recently, origin of ðÁÞ DIA was studied for oxide crystals based on the above-mentioned experimental data. 3,4,[6][7][8] It was concluded that ðÁÞ DIA originated from preferential orientation of bond direction with respect to a magnetic principle axis of crystal. Accordingly a material with high crystal symmetry was expected to posses small ðÁÞ DIA below 1  10 À9 emu/g.…”