Magnetic anisotropy of cobalt-doped gamma ferric oxide

Köster, E.

doi:10.1109/tmag.1972.1067490

Cited by 22 publications

(2 citation statements)

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“…The crystalline anisotropy can be different for cobalt ions doped into the core of the particles and that of the surface doped particles. The anisotropy as well as the coercivity is dependent on the particle size, degree of cobalt doping and the distribution of cobalt ions, and more importantly on the nature of the surface of the particles [14][15][16]. Despite a number of studies on cobalt doped γ -Fe 2 O 3 [17][18][19][20] in bulk form and cobalt ferrite nanoparticles [21,22], less attention has been paid to the synthesis and studies of the magnetic behaviour of cobalt doped γ -Fe 2 O 3 in nanocrystalline form.…”

Section: Introductionmentioning

confidence: 99%

Cobalt doped γ-Fe₂O₃nanoparticles: synthesis and magnetic properties

2005

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We demonstrate here the wet chemical synthesis of cobalt doped γ-Fe2O3 nanoparticles and the subsequent effect on magnetic properties with the variation in dopant concentration. It is observed that cobalt can be homogeneously doped into the γ-Fe2O3 lattice up to 5 mol% without any appreciable change in the particle size ( nm). Further increase in cobalt concentration (10 mol% here) resulted in an increase in particle size ( nm) due to possible adsorption of a cobalt layer on the surface of γ-Fe2O3 nanoparticles rather than complete doping in the iron oxide lattice. The ac susceptibility measurements revealed an increase in blocking temperature (TB) with percentage variation in cobalt doping (2–10%), indicating substitution of Fe3+ ions by Co2+ ions in the γ-Fe2O3 lattice. The dc magnetization measurements showed an increase in saturation magnetization only up to 5%, beyond which it significantly diminished. The reduction in saturation magnetization is attributed to the contribution from surface anisotropy in cobalt coated γ-Fe2O3 nanoparticles.

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Section: Introductionmentioning

confidence: 99%

Cobalt doped γ-Fe₂O₃nanoparticles: synthesis and magnetic properties

2005

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“…wt.% of cobalt was used for the formation of Co-modified ~-Fe 2 0 3 phase. In particulate media, cobalt can be introduced using several processes such as by Co-doping (Koster 1972), by Co-adsorption (Imaoka et al 1978) and by epitaxial surface deposition of Co-ferrite (Kishimoto et al 1979). Location of Co 2 + ions in the lattice of ~-Fe2 O3 determines the nature of anisotropy introduced in the medium and the stability of the medium.…”

Section: Introductionmentioning

confidence: 99%

Growth, magnetic properties and the effect of cobalt addition in metal-organic chemical vapour deposited (MOCVD) gamma iron oxide thin films for magnetic recording applications

1994

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The present study aims at investigating MOCVD technique for the deposition of magnetic oxide thin films using volatile metal-organic compounds as source material. A three-step scheme has been described to form ~,-Fe203 phase starting from ~t-Fe203 films as-deposited in optically heated atmospheric cold wall CVD reactor. Growth of ~-Fe203 in a two-step process has been performed by depositing Fe3 04 phase directly by resistively heated low-pressure CVD (LPCVD) technique. Role of substrate temperature in controlling the oxidation leading to direct formation of metastable ~-Fe2 03 phase (single-step scheme) by atmospheric CVD technique has been described. A new mode of introduction of cobalt in the film, namely heterogeneous dispersion of cobalt in the ~,-Fe203 matrix, has also been described. Crystallographic structure, microstructure and magnetic properties of the films have been studied in detail. Biaxial vector coil and high-temperature magnetic studies were carried out for determining the nature of anisotropy in the 7-Fe203 film. Growth of ~,-Fe203 films in different schemes have been discussed from the studies of growth kinetics in a coldand hot-wall-type reactor chambers.

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