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Determination of Magnetic Moments of Magnetite Nanoparticles Aggregates by Optical Methods

“…In the experiment it is impossible to achieve that the magnetic field switches on instantaneous and consequently it is necessary to consider the influence of magnetic field increasing upon birefringence signal in due course (see Figure 1). We achieved this by means of the integral used in the electrical engineering for calculation of distortions of signals in electric circuits [2]. The calculations have shown the value of parameter R<<1, that testifies to a prevailing role of an induced magnetic moment in orientation of aggregates under the action of a field.…”

“…The colloid solution magnetite nanoparticles in kerosene with volume concentration of 0.1 % was the sample for the research. For measurement of birefringence the standard optical setup analogous presented in [2,5] was used. The helium-neon laser was a light source.…”

“…Quasi-solid aggregates are a groups of the aggregated colloidal particles behaving as one large particle and Microdrops are the drops of high concentrated magnetic fluid weighed in low concentrated one and deformable under the influence of a magnetic field. The presence of aggregates of magnetite nanoparticles in magnetic fluids is confirmed by various methods, such as dynamic light scattering [1], pulsed birefringence in electric and magnetic fields [2], dichroism [3,4], magnetic measurements [5] at al. Experiments give values of the sizes of aggregates about 50-200 nanometers depending on the sample, i.e.…”

Multifunctional biocompatible coatings on magnetic nanoparticles

“…74,75 Experimental studies of aggregation were carried out by optical 76 and diffraction methods. 77 Magnetic fluids become optically anisotropic 78,79 and their viscosity abruptly increases in external magnetic fields. 80 In some cases, experimental results were in qualitative agreement with the conclusions drawn in theoretical studies.…”