Mössbauer Spectroscopy and Surface Analysis

Marco, José F.; Gancedo, J. R.; Monti, Matteo; Figuera, Juan de la

doi:10.1002/9781118714614.ch22

Cited by 3 publications

(4 citation statements)

References 37 publications

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“…This homogeneous composition with depth is quite significant and can have serious implications when seeking a possible application for these films. In a previous work [15], we have found comparing ILEEMS, CEMS and transmission spectra recorded from acicular Fe 2 O 3 nanoparticles (which also have a spinel related structure) very large variations (close to 100 %) of the A:B sextet ratio that suggested an inhomogeneous cation distribution from the surface layers to the nanoparticles bulk. While in these nanoparticles surface effects were clearly evident, probably due to their characteristic shape, the present results indicate that cobalt ferrite films of micrometer thicknesses can be produced by PLD having a relatively homogeneous cation distribution from the surface layers to the bulk.…”

Section: Discussionmentioning

confidence: 83%

“…57 Fe ILEEMS is a non-destructive technique that has been used to study the structural and magnetic properties of the surface of iron based materials. The theoretical and methodological bases of this technique have been reviewed elsewhere [15]. In this technique a channeltron electron multiplier in high or ultra high vacuum is used as the electron detector.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The spectra were collected at room temperature and under high vacuum conditions (1•10 −7 mbar). In ILEEMS a positive bias voltage is applied to the en-trance cone of the channeltron to enhance the detection efficiency of the resonant low-energy electrons that are more surface sensitive than the resonant conversion electrons [15]. With zero bias voltage at the cone an ILEEMS spectrum is just an ordinary Conversion Electron Mössbauer (CEMS) spectrum and, then, a deeper thickness is probed.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Bulk and surface characterisation of micrometer-thick cobalt ferrite films grown by IR PLD

Sánchez-Arenillas

Oujja

Moutinho

et al. 2019

Applied Surface Science

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We have studied micrometer-thick cobalt ferrite films deposited on Si (100) single crystal substrates by nanosecond pulsed laser deposition at 1064 nm.The thickness of the deposited films (1.3 µm) was monitored by AFM. The chemical and structural characterisation of the films was carried out by Raman spectroscopy and transmission Mössbauer spectroscopy at 300 and 26 K. For comparison purposes, transmission Mössbauer data at these two temperatures were also recorded from a commercial cobalt ferrite powder and the home-made target used to grow the films. The surface characterisation was performed by X-Ray Photoelectron Spectroscopy (XPS) and Integral Low Energy Electron Spectroscopy (ILEEMS). XPS showed Co and Fe to be present as Co 2+ and Fe 3+ , as expected for cobalt ferrite. The Raman spectra showed the lines characteristic of cobalt ferrite. The Mössbauer spectra, both in the transmission and backscattering modes, were fitted to two sextets whose hyperfine parameters are in good agreement with those expected from Fe 3+ cations occupying the tetrahedral and octahedral sites in the spinel-related structure. No significant differences were observed in the relative areas of the two sextets in the transmission and ILEEMS spectra, suggesting that the cation distribution at the surface and the bulk are not too different. However, the relative areas of the two components changed drastically with temperature both in the spectra of the films as in those recorded from the cobalt ferrite standards. We discuss the possible origin of the evolution with temperature of those relative areas.

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Section: Discussionmentioning

confidence: 83%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

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Bulk and surface characterisation of micrometer-thick cobalt ferrite films grown by IR PLD

Sánchez-Arenillas

Oujja

Moutinho

et al. 2019

Applied Surface Science

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“…4c). In an ILEEMS spectrum the surface contributions are enhanced 28 , therefore the differences, if any, between the ILEEMS and transmission spectra have to be due to structural/compositional changes in the surface respect to the bulk. Inspection of Fig.…”

Section: Resultsmentioning

confidence: 99%

Strontium hexaferrite platelets: a comprehensive soft X-ray absorption and Mössbauer spectroscopy study

Soria

Jenuš

Marco

et al. 2019

Sci Rep

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Platelets of strontium hexaferrite (SrFe 12 O 19 , SFO), up to several micrometers in width, and tens of nanometers thick have been synthesized by a hydrothermal method. They have been studied by a combination of structural and magnetic techniques, with emphasis on Mössbauer spectroscopy and X-ray absorption based-measurements including spectroscopy and microscopy on the iron-L edges and the oxygen-K edge, allowing us to establish the differences and similarities between our synthesized nanostructures and commercial powders. The Mössbauer spectra reveal a greater contribution of iron tetrahedral sites in platelets in comparison to pure bulk material. For reference, high-resolution absorption and dichroic spectra have also been measured both from the platelets and from pure bulk material. The O-K edge has been reproduced by density functional theory calculations. Out-of-plane domains were observed with 180° domain walls less than 20 nm width, in good agreement with micromagnetic simulations.

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Magnetite and the Verwey transition, from γ-rays to low-energy electrons

Figuera

Marco

2019

Hyperfine Interact

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Mössbauer Spectroscopy and Surface Analysis

Cited by 3 publications

References 37 publications

Bulk and surface characterisation of micrometer-thick cobalt ferrite films grown by IR PLD

Bulk and surface characterisation of micrometer-thick cobalt ferrite films grown by IR PLD

Strontium hexaferrite platelets: a comprehensive soft X-ray absorption and Mössbauer spectroscopy study

Magnetite and the Verwey transition, from γ-rays to low-energy electrons

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