Study of Fe: Al2O3 ion beam sputtered thin films with various iron contents

Thimon, F.; Marest, G.; Moncoffre, N.; Joshi, Sushama; Ogale, S. B.

doi:10.1016/0168-583x(93)90775-2

Cited by 8 publications

(5 citation statements)

References 11 publications

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“…Several authors have observed this singlet given that a single line with similar values for the IS has been reported for iron implanted alumina samples and as-sputtered Fe: Al 2 O 3 thin films. 7,8,[10][11][12]28 We have detected this pattern in Fe-Al 2 O 3 arc-melted samples as well. 29 However, complete agreement is not there on the interpretation of this phase, since both superparamagnetic ␣-Fe and stabilized ␥-Fe have been identified as causing this nonmagnetic contribution.…”

Section: Resultssupporting

confidence: 53%

“…21,22 The magnetic properties of as-deposited and annealed Fe-Al 2 O 3 multilayers and of coevaporated granular Fe-Al 2 O 3 films have also been intensely investigated. [23][24][25][26][27][28] To date, particularly considering the ball-milling process, no systematic investigation of this binary system has been reported. In this sense, in the present study we report results of a structural and Mössbauer investigation carried out on the ball-milled Fe-Al 2 O 3 system.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Mössbauer characterization of the ball-milledFex(Al2O3)100−x system

Paesano

Matsuda

Cótica

et al. 2004

Journal of Applied Physics

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Metal-oxide composites were synthesized by high-energy ball milling of metallic iron ͑␣-Fe͒ and alumina ͑␣-Al 2 O 3 ͒ powders, varying the starting relative concentration and the milling time. The samples were characterized by scanning electron microscopy, x-ray diffraction, and Mössbauer spectroscopy. The results revealed the formation of a FeAl 2 O 3+W spinel phase (hercynite) and of iron (super)paramagnetic nanoprecipitates, in addition to residual magnetic iron and alumina. We also observed that the relative amounts of nanoprecipitates and hercynite for isochronally milled samples were correlated with the sample nominal concentration x, with the precursor iron being relatively more converted in those phases for low x values. Particularly for x = 10 milled sample, the relative amounts of the (super)paramagnetic and spinel phases were observed to increase linearly with the milling time. An x = 20/ 24 h milled sample was annealed in H 2 atmosphere and revealed the reduction of hercynite, with iron phase separation.

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Section: Resultssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Structural and Mössbauer characterization of the ball-milledFex(Al2O3)100−x system

Paesano

Matsuda

Cótica

et al. 2004

Journal of Applied Physics

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“…[7][8][9][10] Thus, the single line present among the individual subspectra is attributed to SPM iron nanoprecipitates. Indeed, several authors have reported a singlet with similar values for the ␦ in iron implanted alumina samples [17][18][19][20][21] and as-sputtered Fe:Al 2 O 3 thin films, 22 and attributed it to nanostructured iron. The same SPM phase was also detected in an earlier work during a systematic arc-melting study of Fe Z (Al 2 O 3 ) 1ϪZ , as reported by Paesano et al 23 They observed that, concurrently to iron in nano and bulk forms, the spinel oxide FeAl 2 O 3ϩY was formed for every iron concentration, Z, in the range 0.02рZр0.60.…”

Section: Resultsmentioning

confidence: 99%

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

Cótica

Zanatta

Rocha

et al. 2004

Journal of Applied Physics

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The system (␣-Fe 2 O 3 ) x (␣-Al 2 O 3 ) 1Ϫx was subjected to 24 h of high-energy ball-milling varying its nominal concentration, x. The milled samples were structurally and magnetically characterized at room temperature by x-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. Mössbauer studies were also performed in the temperature range 250-6 K. As a result of the earlier analyses, it was observed that the milling products were extremely dependent on the hematite starting concentration. In samples with low ␣-Fe 2 O 3 initial concentration ͑i.e., xр0.12), the paramagnetic solid solution ␣-(Fe ⌬Y Al 1Ϫ⌬Y ) 2 O 3 , the ␣-Fe and the FeAl 2 O 4 phases were identified, along with alumina, which was always residual. The presence of spinel and metallic iron was attributed to the stainless-steel vial and balls abrasion. For xϾ0.12, the iron component was no longer present but another magnetic component, corresponding to an aluminum-substituted hematite phase, ␣-(Fe 1Ϫ⌬W Al ⌬W ) 2 O 3 , could be seen to increase with increasing x. This solid solution was shown to be transitional, at room temperature, between two ordering states, weak ferromagnetic and superparamagnetic, the latter resulting from the milling induced particle size reduction. Low temperature Mössbauer spectra revealed the magnetic ordering of both solid solutions, ␣-(Fe ⌬Y Al 1Ϫ⌬Y ) 2 O 3 and ␣-(Fe 1Ϫ⌬W Al ⌬W ) 2 O 3 , and indicated the suppression of the Morin transition for the iron-rich solid solution. The magnetization versus magnetic field curves obtained for samples with xу0.12 revealed, besides a general superparamagnetic character, some hysteretic behavior due to the magnetic phases eventually existing.

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“…4c), in addition to the earlier subspectra, a single line related to non-magnetic iron was also employed in the fitting. Several authors have detected this singlet in iron-alumina or aluminium-hematite milled systems [17,19,20], in iron implanted alumina samples [21][22][23][24] and as-sputtered Fe:Al 2 O 3 thin films [25], although until now there has not been a complete agreement on the interpretation of this phase. It can be credited to either non-magnetic ␣-Fe small clusters, probably with some dissolved aluminium, or to ␥-Fe, stabilized by pressure in alumina.…”

Section: Resultsmentioning

confidence: 97%

High-energy ball-milled (α-Fe2O3)(α-Al2O3) system: A study on the milling time effects

Cótica¹,

Paesano²,

Zanatta³

et al. 2006

Journal of Alloys and Compounds

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Study of Fe: Al2O3 ion beam sputtered thin films with various iron contents

Cited by 8 publications

References 11 publications

Structural and Mössbauer characterization of the ball-milledFex(Al2O3)100−x system

Structural and Mössbauer characterization of the ball-milledFex(Al2O3)100−x system

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

High-energy ball-milled (α-Fe2O3)(α-Al2O3) system: A study on the milling time effects

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