ac susceptibility study of a magnetite magnetic fluid
| Autor: | J. T. Elizalde Galindo, O. E. Ayala-Valenzuela, Cristian E. Botez, José Andrés Matutes-Aquino |
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| Rok vydání: | 2009 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 105:07B524 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.3072783 |
| Popis: | 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 χ=χ′+iχ″ 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 χ″ 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 δ=χ″/χ′ which is related to a magnetic aftereffect. The peak temperature Tp2 is far less than Tp1 and shows an Arrhenius-type depe... |
| Databáze: | OpenAIRE |
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