Please use this identifier to cite or link to this item: http://cimav.repositorioinstitucional.mx/jspui/handle/1004/1018
Ac susceptibility study of a magnetite magnetic fluid
OSCAR EDUARDO AYALA VALENZUELA
JOSE ANDRES MATUTES AQUINO
JOSE TRINIDAD ELIZALDE GALINDO
Acceso Abierto
Sin Derechos Reservados
Magnetic fluid
Magnetite nanometric powder was synthesized from metal salts using a coprecipitation technique. The powders were used to produce magnetic fluid via a peptization method, with hydrocarbon Isopar M as liquid carrier and oleic acid as surfactant. The complex magnetic susceptibility X=X’+iX’’ was measured as a function of temperature T in steps of 2.5 K from 3 to 298 K for frequencies ranging from f =10 to 10 000 Hz. The magnetic fluid real and imaginary components of the ac susceptibility show a prominent maximum at temperatures that increase with the measuring frequency, which is attributed to a spin-glass-like behavior. The peak temperature Tp1 of X’’ depends on f following the Vogel–Fulcher law f = f0 exp[E/kB(Tp1−T0)], where f0 and E are positive constants and T0 is a parameter related to particle interactions. There is another kind of peak temperature, Tp2, in the loss factor tan S=X’’ / X’ which is related to a magnetic aftereffect. The peak temperature Tp2 is far less than Tp1 and shows an Arrhenius-type dependence on f.
2009
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