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Dataset of Operando Exploration of Tribochemical Decomposition in Synthetic FeS2 thin film and Mineral IronPyrite
Muñoz-Cortés, Esmeralda
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Sánchez-Prieto, Jesús
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Zabala, Borja
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Sánchez, Carlos
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Flores, Eduardo
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Flores, Araceli
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Román García, Elisa Leonor
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Ares, José R.
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Nevshupa, Roman
DIGITAL.CSIC
(2023)
Descriptions
Datasets of mass-spectrometry signals were obtained in the experiments with non-thermal tribochemical decomposition of synthetic thin-film iron sulphide and mineral ironpyrite. Tribochemical reactions were studied on a micrometre scale using localized rubbing under ultrahigh vacuum. Mechanically Stimulated Gas Emission Mass-Spectrometry (MSGE-MS) including the Dynamic gas expansion method was used to determine the kinetic parameters of gas emission and the composition of the emitted gases. The study was complemented by structural, morphological, tribological, mechanical and surface analyses. It was found that carbon-containing gases were dominating. The sulfur-containing gases comprised H2S, COS and CS2. The latter two were unexpected. The emission of these gases was traced back to solid-state chemical reactions kinetically controlled by the precursor concentrations and driven through non-thermal mechanisms, which we tentatively assigned to formation of sulfur radicals.
FeS2 thin films were obtained by sulfuration of Fe coatings, which were deposited by thermal evaporation of iron powder (Goodfellow, 99.99%) on soda lime glass substrates under high vacuum. The initial thickness of the Fe coatings was 300±20 nm as measured using quartz crystal microbalance. The Fe coating was transferred into a glass ampoule, which contained a small amount of sulfur powder (Merck, 99.99%) placed at one end. The ampoule was evacuated down to 10-5 mbar and sealed. Then, sulfur was sublimated by heating to 300ºC for 20 h, while sulfur vapour at a pressure of about 0.065 bar reacted with the Fe film. After sulfuration, the coatings were kept in the same sealed ampoules at room temperature until they were characterized. Natural pyrite was used to contrast the results obtained for artificial FeS2 thin film. A sheet of ironpyrite was cut from a native crystal proceeding from Peru mines and polished. X-ray diffraction analysis showed a typical cubic crystal structure of the mineral sample. The iron coatings' crystal structure was analyzed both before and after sulfuration using grazing-angle X-ray diffraction (XRD). This was accomplished by employing Cu Kα radiation and maintaining a fixed incidence angle of 1.7°. To determine the mean crystallite size, the Scherrer formalism was applied to the main diffraction band (200). Film thickness measurements were conducted at the film edge utilizing a stylus profilometer, achieving an accuracy of 10 nm. The mechanical properties of the FeS2 coatings were investigated through nanoindentation (G200, KLA Corp.), utilizing a Berkovich diamond tip in dynamic contact mode. The maximum indentation depth was 100 nm constrained to remain below 10% of the total coating thickness. The loading cycle was carried out at a constant indentation strain rate of 0.1 s-1 and a small oscillating force was superimposed to this loading ramp (75 Hz of frequency, amplitude of 2 nm). Continuous measurement of the contact stiffness was achieved on the basis of the phase lag between the sinusoidal force and the penetration produced. X-ray Photoemission Spectrometry (XPS) was used to obtain information on chemical state of various elements under ultra-high vacuum (UHV) with a pressure below 10-8 Pa. Mg Kα radiation with an energy of 1253.6 eV was employed. To eliminate any airborne adsorbed contaminants from the sample surface, ensuring a pristine surface for subsequent XPS analysis, the samples underwent Ar+ ion sputtering with an energy of 1 keV and an incident angle of 60° with respect to the sample normal. The sputtering depth was around 1.3 Å. It should be noted that Ar+ ions for sputtering can potentially alter the chemical oxidation state of Fe and/or S and/or change the surface composition due to preferential sputtering. No additional treatment was performed. High-resolution XPS analysis of Fe 2p, S 2p, O 1s, and C 1s was conducted through the fitting process employing the minimum possible number of components compatible with the expected chemistry. For instance, both the Fe 2p3/2 and Fe 2 p1/2 spin-orbit peaks were fitted to ensure the coherence of the procedure, while assuming a Shirley background. For the sake of simplicity, only the Fe 2p3/2 bands are discussed here. The S 2p peak was fitted employing a S 2p3/2 S 2p1/2 doublet, considering the theoretical spin-orbit coupling ratio of 1:2. A fixed separation of 1.2 eV between the S 2p3/2 and S 2p1/2 was maintained based on literature for data processing.
1. Dataset of mass-spectrometry time series of mechanically stimulated gas emission from sodium alanate (NaAlH4) pellets under vacuum.-- 2. Dataset of Thermal Programmed Desorption – Mass-Spectrometry (TPD-MS) analysis of sodium alanate.-- 3. Dataset of X-ray diffraction of sodium alanate.-- 4. Dataset of micro-FTIR spectra of pristine and mechanically activated surfaces of pellets of sodium alanate.-- 5. Dataset of Raman spectra measured on the surfaces of pellets of sodium alanate.
Muñoz-Cortés, E., Sánchez-Prieto, J., Zabala, B., Sánchez, C., Flores, E., Flores, A., Román García, E. L., Ares, J. R., & Nevshupa, R. (2023). Dataset of Operando Exploration of Tribochemical Decomposition in Synthetic FeS2 thin film and Mineral Iron Pyrite [Data set]. DIGITAL.CSIC. https://doi.org/10.20350/DIGITALCSIC/15703
Dates
Accepted:
2023-12-11
Available:
2023-12-11
Issued:
2023-12-11
Language
en
Funding References
Funder name: This study was co-funded by Spanish Ministry for Science and Innovation (grants PID2019-111063RB-I00, PID2020-112770RB-C22, PID2020-117573GB-I00, RTI2018-099794-B-I00, and TED2021-129950B-I00) and funding from Madrid Community (project S2018/NMT-4291 TEC2SPACE), Ministry of Science and Innovation of Spain (project CSIC13-4E-1794) and EU (FEDER, FSE).
Rights
openAccess
Creative Commons Attribution Non Commercial Share Alike 4.0 International