Size-dependent superparamagnetic properties of Mn spinel ferrite nanoparticles synthesized from reverse micelles

Authors
Citation
C. Liu et Zj. Zhang, Size-dependent superparamagnetic properties of Mn spinel ferrite nanoparticles synthesized from reverse micelles, CHEM MATER, 13(6), 2001, pp. 2092-2096
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
CHEMISTRY OF MATERIALS
ISSN journal
0897-4756 → ACNP
Volume
13
Issue
6
Year of publication
2001
Pages
2092 - 2096
Database
ISI
SICI code
0897-4756(200106)13:6<2092:SSPOMS>2.0.ZU;2-Q
Abstract
MnFe2O4 nanoparticles in a size range of 4-14 nm have been synthesized from water-in-toluene reverse micelles by using sodium dodecylbenzenesulfonate (NaDBS) as surfactant. The blocking temperature, saturation magnetization, and coercivity of the nanoparticles are clearly size-dependent. The blockin g temperature increases from 20 to 250 K when the mean size of the nanopart icles increases from 4.4 to 13.5 nm. The coercivity at 20 K increases from 30 to 300 Oe with increasing nanoparticle size. The field-dependent magneti zation hysteresis disappears above the blocking temperature. Due to high sa turation field, the saturation magnetization of the nanoparticles has been obtained by the extrapolation of the magnetization vs 1/H plot to 1/H = 0. The saturation magnetization decreases with decreasing nanoparticle size. T he high saturation held and the size-dependent saturation magnetization sug gest the existence of a magnetically inactive layer on MnFe2O4 nanoparticle s. The linear fitting of the saturation magnetization vs 1/d plot gives the thickness of this inactive layer as 0.45 nm.