Iron-implanted sintered alumina studied by RBS, CEMS AND SEM techniques

Donnet, C.; Jaffrézic, H.; Marest, G.; Moncoffre, N.; Tousset, J.

doi:10.1016/0168-583x(90)90390-g

Cited by 20 publications

(9 citation statements)

References 9 publications

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“…Hence the interpretation of D1 as due to Fe 4+ is favoured. It should be noted that this component has no relationship to the proposed Fe 4+ components claimed by other authors [4][5][6] upon high fluence implantation.…”

Section: Discussionmentioning

confidence: 88%

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Mössbauer spectroscopy of 57Fe in α-Al2O3 following implantation of 57Mn*

et al. 2010

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The valence state and annealing reactions of Mn/Fe in single crystalline α-Al 2 O 3 have been determined following low fluence (<10 12 cm −2 ) 60 keV implantations of 57 Mn + (T 1/2 = 1.5 min) and emission Mössbauer spectroscopy on the 57m Fe daughter nuclei in the temperature range from 110-700 K. At 110 K, most probe atoms are found in the Fe 2+ state in amorphous surroundings due to the implantation damage. A fraction of the Fe is found in cubic environment, possibly nano-precipitates of η-Al 2 O 3 . This site is found to disappear from the

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Section: Discussionmentioning

confidence: 88%

“…Several authors [4][5][6] claimed that upon high fluence implantation (∼10 17 57 Fe/cm 2 ) Fe was observed in the 4+ valence state. This claim was disproved by low temperature measurements of Kobayashi et al [7] where it was shown that the spectral features assigned to Fe 4+ were due to fine particles of metallic iron.…”

Section: Introductionmentioning

confidence: 99%

Mössbauer spectroscopy of 57Fe in α-Al2O3 following implantation of 57Mn*

et al. 2010

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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: 94%