DETERMINATION OF PARTICLE-SIZE DISTRIBUTION AND CORRELATION OF PARTICLES IN FERROFLUIDS UNDER THE INFLUENCE OF MAGNETIC-FIELDS

Particle size distribution, structure, and magnetic correlations of ma gnetite particles in ferrofluids are studied with X-ray diffraction me thods and electron microscopy. The accordance of the size distribution s obtained from small-angle X-ray scattering (SAXS), wide angle X-ray diffraction (XRD), and transmission electron microscopy (TEM) is demon strated. Under the influence of a magnetic field the particles of ferr ofluids aggregate to oblong and directed particle clusters. They have a small extension in field direction, caused by a wide size distributi on and the high thermal energy of the particles. The ferrofluids descr ibed here are suitable to simulate the crystallographic situation of t he Finemet alloys in the state of best soft magnetic properties.