NMR of 57Fe, 69Ga and 71Ga in Ga substituted magnetite

Kohout, J.; Gamaliy, E.; Štěpánková, H.; Englich, J.; Procházka, Pavel; Chlan, V.; Brabers, V.A.M.

doi:10.1016/j.jmmm.2004.11.348

Cited by 7 publications

(4 citation statements)

References 6 publications

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“…Figure 5 shows Raman spectra of the thin-film samples before and after annealing. In fact, a precedence of Ga substitution into the tetrahedral A-sites has been confirmed by Kohout et al 39 using nuclear magnetic resonance. However, the annealing process slightly weakens the intensity of the Raman peaks.…”

Section: Resultsmentioning

confidence: 74%

Influence of oxygen precursors and annealing on Fe3O4 films grown on GaN templates by metal organic chemical vapor deposition

Huang¹,

Gu²,

Tang³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Articles you may be interested inElectrical and magnetic properties of Ga1−xGdxN grown by metal organic chemical vapor deposition J. Appl. Phys. 110, 083920 (2011); 10.1063/1.3656019 Lattice template effect on epitaxial γ -Fe 2 O 3 films prepared by metal organic deposition J. Appl. Phys. 107, 053908 (2010); 10.1063/1.3309770Effects of growth temperature on In N ∕ Ga N nanodots grown by metal organic chemical vapor deposition Substrate, annealing, and Mn excess effects on La-Ca-MnO 3 thin films grown by metalorganic chemical vapor deposition: A way to room-temperature T c

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Section: Resultsmentioning

confidence: 74%

Influence of oxygen precursors and annealing on Fe3O4 films grown on GaN templates by metal organic chemical vapor deposition

Huang¹,

Gu²,

Tang³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…The presence of gallium in the activated catalyst suggests that dopant incorporation can occur during the activation procedure since no evidence of gallium incorporation was found in the catalyst precursor. Earlier, Kohout et al and Rećko et al suggested preferential occupation of tetrahedral sites of magnetite by gallium using NMR and Mössbauer spectroscopy, respectively, whereas a study by Wang et al indicated incorporation of gallium into both tetrahedral and octahedral sites using Mössbauer spectroscopy. These inconclusive findings might be due to the fact that the samples were prepared in different ways.…”

Section: Resultsmentioning

confidence: 99%

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

et al. 2022

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A set of doped iron oxides (chromium, aluminum, gallium, indium, manganese, zinc, niobium) were prepared by a one-step coprecipitation/calcination approach evaluated for their WGS activity under industrially relevant conditions and characterized in detail. The WGS activity after ageing the doped catalyst for 4 days at 25 bar follows the order chromium ≈ aluminum > gallium > indium > manganese > zinc > niobium for copper-codoped catalysts. The activated catalysts predominantly consist of magnetite, irrespective of the dopant. Mössbauer spectra of aged catalysts showed that aluminum and zinc occupy both tetrahedral and octahedral sites of magnetite, while chromium, gallium, indium, manganese, and niobium preferentially substitute octahedral iron. The incorporation of trivalent metal ions of similar size to octahedral Fe3+ (i.e., chromium, aluminum, gallium) results in moderate to high CO conversion, irrespective of incorporation in tetrahedral or octahedral sites. The substitution of Fe2+ with Mn2+ results in an increased Fe3+/Fe2+ ratio. Incorporation of Zn2+ in tetrahedral sites (replacing Fe3+ ions) leads to a complex structure where the charge balance is compensated from the octahedral sites. Separate dopant metal oxide phases were observed in indium- and niobium-doped catalysts. XPS shows that copper is present as a separate phase in activated copper-codoped catalysts. Aluminum is identified as the most promising promoter for substituting chromium in commercial high-temperature WGS catalysts on the basis of their similar high CO conversion although incorporation of these dopants into the magnetite structure differed substantially.

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“…NMR provides a tool to probe the local structure by measuring the resonance frequencies and thus the local hyperfine fields. For magnetic materials, the hyperfine field is mainly determined by the influence of the direct neighbour atoms [14][15][16][17], which enables studies of structural properties of bulk and thin film samples on a local (atomic) scale (see for instance [18][19][20][21][22][23][24][25][26][27]). Moreover, the crystalline phase (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Figure24. The field dependence of the new low frequency101 Ru NMR line at 1.3 K for Sr 2 RuGdO 6[114].…”

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confidence: 98%

Nuclear magnetic resonance studies of materials for spintronic applications

Wurmehl¹,

Kohlhepp

2008

J. Phys. D: Appl. Phys.

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Since its discovery in liquids and also in solid matter in 1946, nuclear magnetic resonance (NMR) has been widely established as a standard tool for structural analysis of a wide range of materials. This review outlines recent NMR studies on materials considered to be useful in spintronic applications. Spintronics is a new research field which combines the use of both the charge and the spin of an electron as information carriers, which promises distinct advantages over conventional electronics which makes use only of the charge of electrons. A successful application of materials in spintronic devices requires a detailed knowledge of the interplay between the structure and the magnetic and electronic properties on an atomic scale. NMR probes the local environments of the active nuclei. This local character of NMR arises from local contributions to the hyperfine field, namely, the transferred field which depends on the nearest neighbour atoms and their magnetic moments. This enables NMR to study the structural properties of bulk samples as well as of thin films of spin polarized materials. Moreover, NMR spectroscopy also provides an indirect tool to measure the density of states of spin polarized materials via a measurement of the temperature dependence of the spin–lattice relaxation time. This review starts with an introduction into the basic concepts of NMR followed by a description of the important aspects of a pulsed NMR experiment. Thereafter, information obtained by an NMR experiment is addressed. In the subsequent main part, selected recent NMR studies (published roughly after the year 2000) of materials for spintronic applications are presented including NMR studies of, for example, Co thin films, Heusler compounds, double perovskites and pyrites.

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NMR of 57Fe, 69Ga and 71Ga in Ga substituted magnetite

Cited by 7 publications

References 6 publications

Influence of oxygen precursors and annealing on Fe3O4 films grown on GaN templates by metal organic chemical vapor deposition

Influence of oxygen precursors and annealing on Fe3O4 films grown on GaN templates by metal organic chemical vapor deposition

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

Nuclear magnetic resonance studies of materials for spintronic applications

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