Magnetostatic properties of magnetite colloids

E. E. Bibik - B. Ya. Matygullin - Yu. L. Raikher - M. I. Shliomis

Abstract
The article gives the results of an experimental investigation of the magnetic properties of colloidal dispersions of Fe₃O₄ in kerosene. The curves of the magnetization have a form characteristic for a superparamagnetic substance; this is confirmed by a comparison between the experimental curve and a Langevin function. The results of this comparison are used to evaluate the dimensions of the colloidal particles (the magnetogranulometric method). The evaluation obtained is in agreement with the data of an electron-microscope investigation of a colloid preparation. The particle-size distribution is plotted by measurement of the microphotographs. It is shown that the dependence of the magnetization of a polydisperse colloid on the intensity of the applied field is well described by the superposition of Langevin polynomials. Over the whole investigated interval Qf fields and of concentrations of the solid phase, the magnetization of the colloid is proportional to the concentration.