Sample Holder for SAXS Measurement under Static Magnetic Field

D. F. CORAL; MENDOZA ZÉLIZ, PEDRO; POLLI,J.M; DE SOUSA,M.ELISA; M. B. FERNÁNDEZ VAN RAAP

LNLS activity report

LNLS

Lugar: Campinas; Año: 2012 p. 1 - 2

1518-0204

The issue on whether dynamic properties of magnetic colloids retrieved from quasi static magnetic measurement can be extrapolated to analyze Specific Absorption Rate (SAR) data conducted at high amplitudes and frequencies excitation fields is addressed.  To this end, two colloids of magnetite coated with oleic acid and chitosan in water, displaying high and low specific heat power release (85 and 5 W/gFe3O4)(definir LD y HD) at a field frequency and amplitude of 267 kHz and 52 kA/m, were analyzed.  Both colloids are alike in terms of liquid carrier, surfactant and magnetic phase composition. They display mean sizes of 9.7 (s.d 4.5) and 4.8 (s.d 2.1) nm and hydrodynamic mean sizes of 56.9 (s.d 7.7) and 134.6 (s.d 18.8) nm respectively. The nanoparticles in both colloids relax by Néel mechanism and experimental SAR values are well reproduced within linear response theory using anisotropy density energy retrieved from quasi static magnetic measurement considering that the colloids behave in the interacting superparamagnetic regime.  Cooperative dipolar interaction plays a key role being larger for the high dissipating colloid.