Regensburg 2025 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MA: Fachverband Magnetismus
MA 41: Poster III
MA 41.2: Poster
Thursday, March 20, 2025, 15:00–17:30, P3
Self-ordered colloid of surfactant-free hard ferromagnetic hexaferrite nanoplatelets: SAXS study — •Andrei Chumakov1, Matthias Schwartzkopf1, and Dirk Menzel2 — 1Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2Technische Universität Braunschweig, Braunschweig
A novel type of stable magnetic colloids based on hard magnetic SrFe12O19 particles stabilized by electrical charge and dispersed in water was studied as an object of investigation. The colloidal single crystalline nanoparticles possess a plate-like shape with a mean lateral size of about 50 nm and thickness of 5 nm. Each particle carries a large permanent magnetic moment M and exhibits the highest intrinsic coercivity field HC values of about 0.4 T. The magnetic properties of a ferromagnetic colloid exhibit a minimal magnitude of the coercive force of the order of several Oe., which allows the change of particle's orientation easily under the action of an external magnetic field. Depending on the concentration, the nanoparticle can exist in the water media in the free 'gas', concentrated liquid crystal, and super concentrated 'solid' phases. Structural ordering in the concentrated magnetic colloids of nanoparticles was investigated by SAXS, SEM, and SQUID techniques. It was revealed that the self and externally-induced liquid crystal phase consists of stacks of magnetic nanoplatelets, which can be ordered to nematic or similar phases by the external magnetic field. Various methods for creating a concentrated liquid crystalline phase are considered. The features of interaction within alternating and constant magnetic fields were studied.
Keywords: ferrofluid; hexaferrite; magnetic nanopaticles; SAXS; colloidal solution