Magnetically Induced Crystal Alignment of Calcium Hydrogen Phosphate Dihydrate

Abstract

Calcium hydrogen phosphate dihydrate is a precursor material of hydroxylapatite; the mineral phase of calcified tissues, and is a biomaterial that is known to show high biocompatibility and resorbability in-vivo. It exhibits anisotropic growth and dissolution behaviors, and quite recently, its conversion kinetics into hydroxylapatite has been reported to alter on coatings with distinct crystal alignments. These imply that biological behaviors of polycrystalline calcium hydrogen phosphate dihydrate are affected by crystal alignment. Meanwhile, an intense magnetic field is a useful tool to induce crystal alignment in various nonmagnetic substances. In this study, the possibility to control crystal alignment of polycrystalline calcium hydrogen phosphate dihydrate using a magnetic field has been investigated. Calcium hydrogen phosphate dihydrate powder having plate-like morphology was synthesized and then its deflocculated suspension was consolidated under a magnetic field of up to 3 T. X-ray diffraction measurements showed that the intensity ratio of (121) against (020) increased on the surface perpendicular to the magnetic field with intensifying the magnetic field strength. Under a 3 T magnetic field, high alignment against (121) plane has been observed which is unfamiliar for calcium hydrogen phosphate dihydrate. The results indicate that a magnetic field successfully induced crystal alignment in polycrystalline calcium hydrogen phosphate dihydrate.