Iron self-diffusion in nanocrystalline FeZr thin films

Gupta, Ajay; Gupta, Mukul; Pietsch, U.; Ayachit, S.; Rajagopalanl, S.; Balamurgan, A.K.; Tyagi, AK

doi:10.1016/j.jnoncrysol.2004.07.051

Cited by 15 publications

(9 citation statements)

References 39 publications

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“…The in plane correlation length is also significantly large. The microstructure of the film has been obtained with XRD and CEMS after vacuum annealing of the film in the temperature range of 373-773 K [12]. Up to 423 K the system remains in the amorphous phase and annealing at 473 K results in appearance of a relatively sharp peak corresponding to (110) reflection of α-Fe with an average grain size of 12±1 nm.…”

Section: Resultsmentioning

confidence: 99%

Structural and magnetic properties of ion‐beam sputtered FeZr thin films

Gupta

2004

phys. stat. sol. (c)

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PACS 68.65. Ac, 75.70.Cn Amorphous Fe 85 Zr 15 alloy thin films prepared by co-sputtering of Fe and Zr using ion beam sputtering technique show excellent surface properties. The crystallization behaviour of the films depicts a two step crystallization process -in the first step bcc-Fe precipitates out, while in the second step the remaining amorphous phase transforms into an intermetallic Fe 2 Zr alloy along with bcc-Fe phase. The magnetization measurement of the film shows that there is no significant change in the M-H loop of after the first step of crystallization, however after the second step of crystallization the coercivity increases drastically and the behaviour switches from soft-to-hard magnetic.

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Section: Resultsmentioning

confidence: 99%

Structural and magnetic properties of ion‐beam sputtered FeZr thin films

Gupta

2004

phys. stat. sol. (c)

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“…Continuous curves represent best fit to the data obtained using the computer code [14]. Inset shows the concentration profiles of 57 Fe layer as obtained from the fitting of nuclear reflectivity data of pristine ( [18], however are comparable to diffusivity in nanocrystalline FeZr [19], where diffusion occurs mainly through grain boundaries which are amorphous in nature. These results demonstrate that nuclear resonance reflectivity from isotopic marker layers under standing wave conditions can be used to study self-diffusion with an accuracy which is roughly an order of magnitude better than that obtainable using conventional techniques like SIMS.…”

Section: Diffusion Studies Using X-ray Standing Wavesmentioning

confidence: 99%

Study of nano-scale diffusion in thin films and multilayers

et al. 2008

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It is shown that x-ray reflectivity and x-ray fluorescence under standing wave conditions can be used to study atomic diffusion with an accuracy of a fraction of a nanometer. Both the techniques can be made isotope selective by making use of nuclear resonance scattering from a Mössbauer active isotope. The techniques have been used to study self-diffusion of Fe in amorphous and nano-crystalline alloys of FeZr and FeN. The observed correlation of the activation energy E with preexponent factor D 0 confirms that in amorphous FeZr alloy diffusion takes place via collective motion of a group of atoms. Even in nanocrystalline alloys it is found that atomic diffusion occurs mainly through grain boundaries which are amorphous or highly disordered in nature.

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“…If the diffusion takes place from the grain boundaries which are not so well-ordered, the diffusion mechanism will lead to a situation similar to amorphous alloys. 22 In an earlier study, we measured the Fe self-diffusion in a nearly equiatomic amorphous and nonmagnetic FeN alloy 18 and found E Fe =1.3±0. 23 This means that FeN is expected to be more stable as compared to Fe 2 N and therefore E for Fe and N self-diffusion should be high in FeN as compared to Fe 2 N. Though the differences in the obtained values of diffusivity in both samples can be understood in terms of energetics of iron nitrides, it is the difference between the Fe and N selfdiffusion which is counter intuitive as the atomic size of Fe (r Fe = 0.1274 nm) is larger than N (r Fe /r N ≈ 1.6).…”

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Fe and N self-diffusion in non-magnetic Fe:N

Gupta,

Gupta

et al. 2010

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Fe and N self-diffusion in non-magnetic Fe:N has been studied using neutron reflectivity. The isotope labelled multilayers, [Fe:N/ 57 Fe:N] 10 and [Fe:N/Fe 15 :N] 10 were prepared using magnetron sputtering. It was remarkable to observe that N diffusion was slower compared to Fe while the atomic size of Fe is larger compared to N. An attempt has been made to understand the diffusion of Fe and N in non-magnetic Fe:N.Iron nitrides (Fe:N) show a variety of structures and magnetic properties with a variation in the nitrogen content. With an increasing atomic percentage ( at. % N), their major phases are: Fe 16 N 2 , Fe 4 N, Fe 3 N, Fe 2 N, FeN and Fe 3 N 4 . For ≤25 at. % N, the Fe:N phases are magnetic. 1 A lot of attention has been driven to α ′′ − Fe 16 N 2 (∼11 at. % N) due to the presence of the so-called giant magnetic moment in this compound. 2,3 Around 20 at. % N, γ ′ − Fe 4 N phase is formed which has a well-defined magnetic properties and crystal structure. 4 Very recently the γ ′ phase has received a lot of interest due to its chemical inertness and mechanically hard surfaces making it a suitable alternative to pure Fe in magnetic devices. [4][5][6][7][8] Between 25-33 at. % N the Fe:N are known as ǫ − Fe x N (2 ≤ x ≤ 3), and as N at. % increases from 25% to 33%, the phase changes from ferromagnetic Fe 3 N to paramagnetic Fe 2 N at room temperature. Earlier it was not possible to produce the Fe:N phases containing more than 33 at. % N but by using reactive sputtering 9-11 and pulsed laser deposition techniques, 12 the Fe:N phases with >33 at. % N were produced. Around 50 at. % N, the FeN phases have cubic ZnS and/or NaCltype structures which are known as γ ′′ and/or γ ′′′ . The Fe 3 N 4 phase with even more than 50 at. % N was predicted by Ching et al. 13 , but has not been evidenced experimentally.Recently, the ǫ − Fe 2 N and γ ′′ /γ ′′′ phases have been used as a precursor to prepare γ ′ − Fe 4 N phase for its use in the spintronic devices. [5][6][7] In the present work, we have prepared single phase ǫ − Fe 2 N and γ ′′′ − FeN compounds and studied the self-diffusion of Fe and N. A proper understanding of the stability and nitride formation requires the knowledge of both Fe and N selfdiffusion at atomic length scales. However, there are no studies on measurements of both Fe and N self-diffusion in non-magnetic Fe:N. Conventional techniques to measure self-diffusion (e.g. secondary ion mass spectroscopy, radioactive tracer etc.) have depth resolutions of several a)

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Iron self-diffusion in nanocrystalline FeZr thin films

Cited by 15 publications

References 39 publications

Structural and magnetic properties of ion‐beam sputtered FeZr thin films

Structural and magnetic properties of ion‐beam sputtered FeZr thin films

Study of nano-scale diffusion in thin films and multilayers

Fe and N self-diffusion in non-magnetic Fe:N

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