EXPERIMENTAL AND THEORETICAL INVESTIGATIONS ON AGGLOMERATION OF MAGNETIC COLLOIDAL PARTICLES IN MAGNETIC FLUIDS

Macro-clusters formation of the magnetic colloidal particles in magnetic fluids is investigated. Experiments of an optical microscope observation of the macro-clusters formation and of anomalous light scattering by the magnetic fluid are reported. Looking upon the anomalous light scattering of the magnetic fluid as a kind of critical opalescence and using Debye's opalescence theory, we derive a thermodynamical instability theory of the colloidal particles' dispersion. Relations among the instability theory of Cebers, that of Sano and Doi, and ours are discussed. An interaction energy among the colloidal particles is evaluated from the light scattering experiment. Similarities among the macro-cluster formation, spinodal decomposition of precipitation-type magnetic alloys, and flux-line lattice formation in type-II superconductors are discussed.