EFFECT OF CRYSTALLINE PROPERTIES ON COERCIVE FORCE IN IRON ACICULAR FINE PARTICLES.

Article abstract of DOI:10.1007/BF01154588

Crystallographic properties and their size dependence in acicular fine particles of iron prepared by reduction from alpha -FeOOH were investigated by transmission electron microscopy and compares with magnetic properties. Although larger particles with an average needle length of 0. 5 mu m and smaller ones of 0. 2 mu m length have single domain configuration, the former are crystallographically polycrystalline while the latter are single crystal with a left bracket 100 right bracket axial orientation, an easy magnetization direction of iron. The coercive force principally yielded by external shape anisotropy is higher in smaller particles in spite of their inferior axial ratio. The intrinsic magnetocrystalline anisotropy is inferred to be the most responsible to give rise to this increase of coercive force. The experimentally obtained values of magnetic properties are also compared with the theoretical estimation.