A high-pressure Raman study of FeTiO3 ilmenite: Fermi resonance as a manifestation of Fe-Ti charge transfer

Vennari, Cara E.; Williams, Quentin

doi:10.1007/s00269-021-01151-9

Cited by 11 publications

(6 citation statements)

References 44 publications

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“…However, the normal Raman signals for ilmenite are expected to be at 681 (A g ν1), 371 (A g ν3), 333 (E g ν3), and 226 (A g ν4) cm −1 . [ 43 ] When ilmenite is subjected to high pressure, its Raman peaks are shifted to higher wavenumbers. Specifically, the peaks A g ν1, A g ν3, and E g ν3 are shifted linearly with the increase of the pressure, whereas A g ν4 increases in a nonlinear way because of Fermi resonance effects.…”

Section: Results and Discusionmentioning

confidence: 99%

“…Specifically, the peaks A g ν1, A g ν3, and E g ν3 are shifted linearly with the increase of the pressure, whereas A g ν4 increases in a nonlinear way because of Fermi resonance effects. [ 43 ] The changes because of pressure are not completely reversible when ilmenite is back to atmospheric pressure, [ 43 ] and the shift observed in our Raman spectra may be because of the incomplete return of an ilmenite, which was once subjected to high pressures. In addition, the meteorite also suffered high temperatures that makes the opposite effect on the peaks, shifting them to lower wavenumbers [ 44 ] increases the complexity to understand the changes on the Raman spectra.…”

Section: Results and Discusionmentioning

confidence: 99%

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Development of non‐destructive analytical strategies based on Raman spectroscopy and complementary techniques for Mars Sample Return tested on Northwest Africa 1950 Martian meteorite

Coloma

García‐Florentino

Huidobro

et al. 2022

J Raman Spectroscopy

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The Mars Sample Return (MSR) is a near future mission to return samples from the surface of Mars to the Earth. The field operations to carry out data collection, selection of the samples, and sampling procedure, mainly related to the CanMars MSR analog mission, are well‐studied and published. In contrast, studies related to the methodology implemented to characterize the mineralogy of the returned samples are scarcer and focused on biosignature detection. This work presents a non‐destructive analytical methodology based on Raman microscopy (single point and imaging), micro‐energy dispersive X‐ray fluorescence imaging analysis, and scanning electron microscopy coupled to energy dispersive spectroscopy that could be used as a first analytical characterization for the Martian samples that will be returned to the Earth in the upcoming MSR mission, before any destructive analysis. The analytical methodology has been tested on a fragment of the Northwest Africa 1950 Martian meteorite, which gives us a mineralogical characterization of the meteorite. This methodology also allowed to define several chemical reactions taking place in some of the mineral phases (olivines and ilmenite) of the meteorite. In addition to the geochemical characterization of the samples, the fact that this methodology allows to assess the chemical transformations in several minerals gives important clues for describing mineral processes and geological evolution that took place on Mars. This work also shows the advantages and disadvantages that each of the techniques employed has when performing a mineralogical characterization, the information that each one can provide and the importance of combining them.

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Section: Results and Discusionmentioning

confidence: 99%

Section: Results and Discusionmentioning

confidence: 99%

Development of non‐destructive analytical strategies based on Raman spectroscopy and complementary techniques for Mars Sample Return tested on Northwest Africa 1950 Martian meteorite

Coloma

García‐Florentino

Huidobro

et al. 2022

J Raman Spectroscopy

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“…Furthermore, a pressure-induced Fermi resonance between fundamental modes were reported in tetramethylurea and 7,7,8,8-tetracyanoquinodimethane [19,20], where an exponential relationship between Raman intensity ratio to pressure was proposed. In the latest study, a Fermi resonance between the lowest frequency Ag symmetry peaks (ν4 and ν5) between ∼10 and ∼30 GPa has been observed in ilmenite [21]. The bend/umbrella-stretch Fermi resonance has been captured by measuring vibrational spectra of the methyl groups in monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) monomers and their clusters, the Fermi resonance pattern could be explained by a simple picture based on the coupling among nine quantum states which is widely applicable to FR in various types of organic molecules [22].…”

Section: Introductionmentioning

confidence: 94%

Pressure-induced Fermi resonance between fundamental modes in phthalic anhydride

Liu

Chen

Liu

et al. 2022

J. Phys.: Condens. Matter

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In-situ high-pressure Raman spectra of phthalic anhydride (PA) have been measured up to 16 GPa through diamond anvil cell (DAC) technique. The results show that all the Raman bands are blue-shifted with the increase of pressure, accompanied by appearance of some new bands. A Fermi resonance phenomenon of the two Raman fundamental modes of PA at 773 cm-1 and 801 cm-1 is proposed at pressures above 6.6 GPa, where a possible first-order phase transition occurs. The pressure-induced changes of Fermi resonance parameters, e.g., intensity ratio, coupling coefficient and frequency gap of unperturbed transition, are discussed.

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“…Several isostructural compounds such as (Ni; Fe; Mg)TiO3 exhibit the same Raman line around 700 cm -1 . It corresponds to the mode of vibration A1g of symmetrical elongation of octahedron MO6 [36]. The XPS spectra of the CoTiO3 and Co2TiO4 phases are illustrated in Figures 6A and 6B, respectively.…”

Section: Characterizationmentioning

confidence: 99%

Catalytic Performances of Co/TiO2 Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene: Effect of CoTiO3 and Co2TiO4 Phases Formation

Mahir¹,

Brik²,

Benzaouak³

et al. 2023

Preprint

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Co/TiO2 catalysts with different cobalt loadings (3.8, 7.5 and 15 wt%) were prepared by impreg-nation method of Co(NO3)2 .6H2O over titania. Samples containing Co(NO3)2 .6H2O and TiO2 in stoichiometric proportions in order to obtain CoTiO3 and Co2 TiO4 phases were also synthesized. The effect of the calcination treatment at two different temperatures, 550 and 1150 °C was investigated. Characterizations by several techniques, such as XRD UV-vis-NIR, DRS, Raman and XPS were carried out. XRD showed the coexistence of three phases: CoTiO3; Co2TiO4 and Co3O4 after calci-nation at 550°C, while the calcination at high temperature (1150°C) leads to single-phase systems (CoTiO3 or Co2TiO4). Diffuse reflection and XPS spectroscopy showed that divalent cobalt occupies octahedral sites in the ilmenite phase and both tetrahedral and octahedral sites in the spinel phase. The catalytic performances of the prepared catalysts, calcined at the two different temperatures, were evaluated in the oxidative dehydrogenation reaction (ODH) of ethane to ethylene. The con-version values were almost comparable for all the samples, calcined at 550 °C, and comparable the ethylene selectivity were recorded, slightly higher only in the case of CoTiO3. The calcination at 1150°C did not modify the overall activity (ethane conversion values around 20%), however, the production of COx becomes more significant. The study examined the influence of the reaction mixture composition, specifically the presence of water, and reveals a slight increase in the yield of ethylene accompanied by a decrease in the overall catalyst activity. This behavior is likely attributed to an increase in the surface concentration of hydroxyl species (OH), resulting in heightened surface acidity.

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A high-pressure Raman study of FeTiO3 ilmenite: Fermi resonance as a manifestation of Fe-Ti charge transfer

Cited by 11 publications

References 44 publications

Development of non‐destructive analytical strategies based on Raman spectroscopy and complementary techniques for Mars Sample Return tested on Northwest Africa 1950 Martian meteorite

Development of non‐destructive analytical strategies based on Raman spectroscopy and complementary techniques for Mars Sample Return tested on Northwest Africa 1950 Martian meteorite

Pressure-induced Fermi resonance between fundamental modes in phthalic anhydride

Catalytic Performances of Co/TiO2 Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene: Effect of CoTiO3 and Co2TiO4 Phases Formation

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