Size analysis of single-core magnetic nanoparticles

• Single-core iron-oxide nanoparticles with nominal core diameters of 14 nm and 19 nm were analyzed with a variety of non-magnetic and magnetic analysis techniques, including transmission electron microscopy (TEM), dynamic light scattering (DLS), static magnetization vs. magnetic field (M-H) measurements, ac susceptibility (ACS) and magnetorelaxometry (MRX). From the experimental data, distributions of core and hydrodynamic sizes are derived. Except for TEM where a number-weighted distribution is directly obtained, models have to be applied in order to determine size distributions from the measurand. It was found that the mean core diameters determined from TEM, M-H, ACS and MRX measurements agree well although they are based on different models (Langevin function, Brownian and Néel relaxation times). Especially for the sample with large cores, particle interaction effects come into play, causing agglomerates which were detected in DLS, ACS and MRX measurements. We observed that the number and size of agglomerates can be minimized by sufficiently strong diluting the suspension.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Brownian and Néel relaxation

Dynamic light scattering

Magnetization

Single-core nanoparticles

Size distribution

Transmission electron microscopy

Agglomeration

Electron microscopy

High resolution transmission electron microscopy

Light scattering

Magnetic susceptibility

Magnetism

Nanoparticles

Ac susceptibility (ACS)

Brownian

Iron oxide nanoparticle

Langevin functions

Magnetic nano-particles

Magnetorelaxometry (MRX)

Static magnetization

Weighted distribution

Nanomagnetics

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