XPS study on La0.67Ca0.33Mn1−xCoxO3 compounds

Dudric, Roxana; Vlădescu, A.; Rednic, Vasile; Neumann, M.; Deac, I. G.; Tetean, R.

doi:10.1016/j.molstruc.2014.04.065

Cited by 103 publications

(34 citation statements)

References 36 publications

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“…4-left panel) exhibits a maximum between 529 and 530 eV, as well as shoulder and tail extending towards higher binding energies (BEs), which can be deconvoluted into several components. [21,[23][24] Analysis of the single components of the O 1s region can be found in Table S4. The higher BE contributions to the O 1s spectra contains contributions from hydroxyl groups (531.2 eV, peak 3), carbonyl groups (532.4 eV, peak 4) and adsorbed water (533.8 eV, peak 5).…”

Section: Temperature Dependence Of Surface Compositionmentioning

confidence: 99%

Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction

et al. 2018

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LaMnO 3 has been identified as one of the most active systems towards the 4-electron oxygen reduction reaction (ORR) under alkaline conditions, although the rationale for its high activity in comparison to other perovskites remains to be fully understood. LaMnO 3 oxide nanoparticles are synthesised by an ionic-liquid based method over a temperature range of 600 to 950 8C. This work describes a systematic study of the LaMnO 3 properties, from bulk to the outermost surface layers, as a function of the synthesis temperature to relate them to the ORR activity. The bulk and surface composition of the particles are characterised by transmission electron microscopy, X-ray diffraction, X-ray absorption and X-ray photoemission spectroscopy (XPS), as well as low-energy ion scattering spectroscopy (LEIS). The particle size and surface composition are strongly affected by temperature, although the effect is non-monotonic. The number density of redox active Mn sites is obtained from electrochemical measurements, and correlates well with the trends observed by XPS and LEIS. ORR studies of carbon-supported LaMnO 3 employing rotating ring-disk electrodes show a step increase in the mean activity of individual surface Mn sites for particles synthesised above 700 8C. Our analysis emphasises the need to establish protocols for quantifying turn-over frequency of single active sites in these complex materials to elucidate appropriate structure-activity relationships.[a] Dr.

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Section: Temperature Dependence Of Surface Compositionmentioning

confidence: 99%

Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction

et al. 2018

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“…Anyhow, the XPS still serves as a powerful tool to investigate the electronic structure of the cobalt and manganese cations in the compound. Based on the relatively large electron mean free path for the Co 2p and Mn 2p photoelectrons (larger than 1.5 nm) the spectra shown reveals chemical information from buried oxide layers [20][21][22][23][24][25] . At the present conditions, although a detailed analysis of the cobalt and manganese 2p regions are difficult, one can yet address the Co and Mn chemical state based on the spectral features.…”

Section: B X-ray Photoelectron Spectroscopymentioning

confidence: 99%

Training-induced inversion of spontaneous exchange bias field on La1.5Ca0.5CoMnO6

Bufaiçal

Finkler

Coutrim

et al. 2017

Journal of Magnetism and Magnetic Materials

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In this work we report the synthesis and structural, electronic and magnetic properties of La1.5Ca0.5CoMnO6 double-perovskite. This is a re-entrant spin cluster material which exhibits a non-negligible negative exchange bias effect when it is cooled in zero magnetic field from an unmagnetized state down to low temperature. X-ray powder diffraction, X-ray photoelectron spectroscopy and magnetometry results indicate mixed valence state at Co site, leading to competing magnetic phases and uncompensated spins at the magnetic interfaces. We compare the results for this Cadoped material with those reported for the resemblant compound La1.5Sr0.5CoMnO6, and discuss the much smaller spontaneous exchange bias effect observed for the former in terms of its structural and magnetic particularities. For La1.5Ca0.5CoMnO6, when successive magnetization loops are carried, the spontaneous exchange bias field inverts its sign from negative to positive from the first to the second measurement. We discuss this behavior based on the disorder at the magnetic interfaces, related to the presence of a glassy phase. This compound also exhibits a large conventional exchange bias, for which there is no sign inversion of the exchange bias field for consecutive cycles.

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“…), respectively. [30][31][32][41][42][43] It is interesting to note that the LCO deposition leads to as hift in the lattice oxygen peak toward al ow BE value by about 0.3 eV as well as an increase in the peak intensity for the adsorbed oxygen, as presented in the inset of Figure 2c.S uch differences in the lattice and the adsorbed oxygen signals may be indicative of an overlay of oxygen signals from LCO, LSM, andY SZ and the outstanding ability of LCO to adsorb oxygen. [35,36,43] The presence of Mn, Sr,Y ,a nd Zr was confirmed from their elementalX PS spectra (Figure S3 in the SupportingI nformation).…”

Section: Resultsmentioning

confidence: 84%

“…[30,31,41] The La 3d spectrum has two spin-orbit doublet peaks of La 3d 5/2 and La 3d 3/2 (BE = 833.5 and 837.3 eV for La 3d 5/2 and BE = 850.4 and 854.3 eV for La 3d 3/2 )o wing to electron transfer from the oxygen ligands to La 4f. [30][31][32]42] The O1ss pectrum shows two main peaks at 528.6 and 530.5 eV,w hicha re ascribed to the lattice oxygen (O 2À )a nd the adsorbed oxygen species (O À ,…”

Section: Resultsmentioning

confidence: 99%

High‐Performance Solid Oxide Fuel Cell with an Electrochemically Surface‐Tailored Oxygen Electrode

et al. 2018

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State-of-the-art cathodes for solid oxide fuel cells (SOFCs), such as (La,Sr)MnO -(Y O ) (ZrO ) (LSM-YSZ), suffer from sluggish oxygen reduction reaction (ORR) kinetics at reduced temperatures, leading to a significant decline in their performance. Herein, we report a tailored SOFC cathode with high ORR activity at intermediate temperatures using a simple but effective approach based on "electrochemical" surface modification. The proposed process involves chemically assisted electrodeposition (CAED) of a metal hydroxide (LaCo(OH) ) on LSM-YSZ surfaces followed by in situ thermal conversion of LaCo(OH) to perovskite-type LaCoO (LCO) nanoparticles during the SOFC startup. This method facilitates easy loading of the LCO nanoparticles with a precisely controlled morphology without the need for repeated deposition/annealing processes. An anode-supported SOFC with the LCO-tailored LSM-YSZ electrode exhibits a remarkably increased power density, approximately 180 % at 700 °C, compared with an SOFC with the pristine electrode as well as excellent long-term stability, which are attributed to the beneficial role of the CAED-derived LCO nanoparticles in enlarging the active areas for ORR and promoting oxygen adsorption/diffusion. This work demonstrates that controlled surface tailoring of the cathode by CAED could be an effective approach for improving the performance of SOFCs at reduced temperatures.

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XPS study on La0.67Ca0.33Mn1−xCoxO3 compounds

Cited by 103 publications

References 36 publications

Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction

Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction

Training-induced inversion of spontaneous exchange bias field on La1.5Ca0.5CoMnO6

High‐Performance Solid Oxide Fuel Cell with an Electrochemically Surface‐Tailored Oxygen Electrode

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XPS study on La0.67Ca0.33Mn1−xCoxO3 compounds

Cited by 103 publications

References 36 publications

Mean Intrinsic Activity of Single Mn Sites at LaMnO3 Nanoparticles Towards the Oxygen Reduction Reaction

Mean Intrinsic Activity of Single Mn Sites at LaMnO3 Nanoparticles Towards the Oxygen Reduction Reaction

Training-induced inversion of spontaneous exchange bias field on La1.5Ca0.5CoMnO6

High‐Performance Solid Oxide Fuel Cell with an Electrochemically Surface‐Tailored Oxygen Electrode

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Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction

Mean Intrinsic Activity of Single Mn Sites at LaMnO₃ Nanoparticles Towards the Oxygen Reduction Reaction