<I>In-Situ</I> Observation of Crystal Alignment under a Magnetic Field Using X-ray Diffraction

Abstract

The crystal alignment behavior of bismuth particles in the presence of an imposed static magnetic field was examined in situ by X-ray diffraction. Because the c-plane of a bismuth crystal is aligned perpendicular to the direction of a magnetic field, the temporal variation in the (110) peak intensity of bismuth was measured by X-ray diffraction to determine the crystal alignment. The alignment time decreased as the magnetic field strength increased. This tendency is similar to that calculated for the relaxation time. The difference in the magnetic susceptibility between the magnetically easy and hard axes is the driving force for the crystal alignment, and aggregation of the bismuth particles decreases this driving force. The effective difference in magnetic susceptibility for aggregated bismuth particles was estimated by measuring the alignment time of the particles under magnetic fields of various strengths. The estimated effective difference in magnetic susceptibility generally increases with a decreasing magnetic field strength. Furthermore, the interference to crystal rotation caused by the interaction between the induced current and the imposed magnetic field is negligible in this study. To decrease the strength of the magnetic field required for alignment of crystals, the number of small particles should be reduced.

In situ neutron diffraction study of aligning of crystal orientation in diamagnetic ceramics under magnetic fields

“…1 One of the methods to control the orientation is using magnetic fields even for diamagnetic and antiferromagnetic materials. 9 Consequently, the orientation process has not yet been fully understood. Recent developments of technologies on superconducting magnets have made it possible for us to get the textured structures even in diamagnetic ceramics with a small magnetic anisotropy.…”

Rotational Diffusion Model of Magnetic Alignment

“…7,9) Let us consider a particle with the angle against the magnetic field along the X 3 -axis, as shown in Fig. 1.…”

Determination of anisotropic magnetic susceptibility of a biaxial crystal via orientational fluctuation of its microcrystalline suspension under magnetic field

“…The in situ diffraction measurement of a suspension undergoing magnetic alignment has been reported for metal, 16) ceramics, 17) and organic materials 18) to elucidate the align-ment process. In this work, we determine the r values [ ð 2 À 3 Þ=ð 1 À 2 Þ] of L-alanine and D-mannitol crystals by in situ X-ray measurement of the suspension of their microcrystalline powder.…”