XPS studies on strontium compounds

Young, Vaneica Y.; Otagawa, T.

doi:10.1016/0378-5963(85)90083-2

Cited by 98 publications

(33 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both are indicators of increasingc oncentrationso fs urface carbonates. [42,[59][60] We note that the apparent carbonate formation (presumably from the CO 2 in ambient air) also increases when reducingt he Cacontaining LCMA6464. LCMA6464 forms carbonates at al ower degree, compared to the LSMA compositions.…”

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 80%

“…[14] Formation of surfacecarbonates Formation of surfacec arbonates by am etal oxide redox material in contact with the CO 2 oxidanto fasolar fuel production cycle is undesirable since the carbonates block redox-active surfaces ites and, in turn, diminish the redoxp erformance and chemicals tability of the metal oxide.A lkaline-earth metals, like Sr and Ca, may readily form carbonates;t herefore, the following discussion quantifies the extent of carbonate formation at perovskite surfaces. [44,[57][58][59][60] The Ca 2p peak was deconvoluted into two sets of 2p 3/2 and2 p 1/2 signals by fixing the ratio between the areaso ft he 2p 3/2 and 2p g signals to 0.5, as described previously. The spectra for LSMA8282, LSMA8228, LSMA2882, and LCMA6464 are given in the Supporting Information (cf.…”

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

“…For example, 3.4 and 0.8 at %S rw as detected in LSMA8228 [44,[57][58][59][60] O1sX PS spectrabetween5 37 and 525 eV of d) LSMA6446,e )LSMA6464, f) LSMA4664, in as-prepared (top, d = 0) and reducedsamples (bottom, d > 0), and g) x Sr as afunction of y Al with the red crossesm arkingthe displayed XPS spectra. For example, 3.4 and 0.8 at %S rw as detected in LSMA8228 [44,[57][58][59][60] O1sX PS spectrabetween5 37 and 525 eV of d) LSMA6446,e )LSMA6464, f) LSMA4664, in as-prepared (top, d = 0) and reducedsamples (bottom, d > 0), and g) x Sr as afunction of y Al with the red crossesm arkingthe displayed XPS spectra.…”

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

“…To interpret the data, all Sr 3d spectra were deconvoluted into two sets of 3d 5/2 and 3d 3/2 signals, attributed to Sr 2 + ions in SrO (low BE, dark orange deconvolution peaks) and in SrCO 3 (high BE, light orange deconvolution peaks), with each doublet separated bỹ 1.8 eV and ab ranching ratio between the peaks at higher and lower BE of 2/3. [44,[57][58][59][60] The Ca 2p peak was deconvoluted into two sets of 2p 3/2 and2 p 1/2 signals by fixing the ratio between the areaso ft he 2p 3/2 and 2p g signals to 0.5, as described previously. [57] TheO 1s spectra of all materials show two core level features at BE values of around5 29 eV and 532 eV.D econvolutionw as done into four oxygen species, as suggested by Merino et al [42] The peak at low BE is attributed here to the lattice oxygen (O 2À ), [42,[61][62][63] whereas the three remaining peaks are attributed to electron-richer species (i.e.,adsorbed oxygen (O 2 2À /O À ), [64,65] hydroxyl (OH À ) [66] and carbonate (CO 3 2À ) [42,67] speciesa nd chemisorbed water, [42,66,68] listedf rom lowest to highest BE, respectively).…”

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

See 3 more Smart Citations

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

et al. 2017

View full text Add to dashboard Cite

Perovskites are attractive candidates for the solar-driven thermochemical redox splitting of CO and H O into CO and H (syngas) and O . This work investigates the surface activity of La Sr Mn Al O (0≤x≤1, 0≤y≤1) and La Ca Mn Al O . At 1623 K and 15 mbar O , the oxygen non-stoichiometry of La Sr Mn Al O increases with the strontium content and reaches a maximum of δ=0.351. X-ray photoelectron spectroscopy analysis indicates that manganese is the only redox-active metal at the surface. All La Sr Mn Al O compositions exhibit surfaces enriched in manganese and depleted in strontium. We discuss how these compositional differences of the surface from the bulk lead to the beneficially higher reduction extents and lower strontium carbonate concentrations at the aluminum-doped surfaces. Using first principles calculations, we validate the experimental reduction trends and elucidate the mechanism of the partial electronic charge redistribution upon perovskite reduction.

show abstract

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 80%

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

Section: Surface Enrichment Of Redox Active Mn Cationsmentioning

confidence: 99%

See 2 more Smart Citations

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

et al. 2017

View full text Add to dashboard Cite

show abstract

“…[43,56,57] Indeed, SrO (Sr source of the PLD target) is well-known for its high affinity with CO 2 turning to SrCO 3 very easily under air exposure. [44,58,59] Thus, the Sr content (3.7 at.%) attributed to strontium carbonates will be related to the major part of the carbon "C1sÀ CO 3 " content (around 70%).…”

Section: From Nanostructured To Smooth Svo Thin-filmsmentioning

confidence: 99%

Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO₃ Thin‐Films Grown by Pulsed Laser Deposition

et al. 2019

View full text Add to dashboard Cite

Since SrVO3 (SVO) can be used as a highly conductive material for perovskite heterostructures, the control of surface morphology and chemistry of such thin‐films are essential. Using pulsed laser deposition, two distinct topographies can be produced. Thus, by tuning oxygen pressure in the growth chamber during cooling, smooth or partially covered by self‐oriented Sr3V2O8 nanorods surfaces can be grown. This study manages to correlate the two typical topographies, revealed by atomic force microscopy (AFM), with their chemical compositions obtained by X‐ray photoelectron spectroscopy (XPS). At first, a model describes their initial surface chemistry through the Sr/V cationic ratio and the (Sr+V)/Oox ratio. Furthermore, using sputter‐depth profiling, post‐thermal treatments and wet chemical etching, SVO thin‐film chemical compositions are extensively studied. We demonstrate that they are composed of stoichiometric SVO phase covered by Sr‐rich layer on top. Finally, treatment in water for 180 seconds helps to remove Sr‐rich phases. Sr3V2O8 nanorods are found selectively dissolved leaving a surface nano‐imprint. Moreover, on smooth SVO surfaces, a balanced Sr/V cationic ratio of 1.0±0.1 is obtained. These results appear very promising for SVO thin‐films surface preparation and further development as electrodes for electronic devices.

show abstract

Composition and Shape Control of Crystalline Ca_1–_xSr_xTiO₃ Perovskite Nanoparticles

Mao

Wong

2005

Advanced Materials

View full text Add to dashboard Cite

slightly larger than the attraction, barely keeping SWCNTs dispersed. Any effects to even weakly shield the electrostatic repulsion resulted in immediate coagulation. A similar situation prevails in anhydrous polar solvents where electrodeposition is always competing against spontaneous coagulation. At higher electric fields, SWCNT aggregates visible to the naked eye were seen to grow in the dispersion solution, indicating that spontaneous coagulation was in progress. The irregularly shaped aggregates did not adhere strongly to the anode surface, as they were easily washed away by rinsing with solvents. Thus, the reduced density at higher potentials is due to coagulation. Also, the same consideration rejects the possibility of post-deposition, i.e., adsorption of bundles without DC field.The electric field in a parallel-plate capacitor depends only on the electric potential and the distance between the electrodes. We have found that the deposition density is independent of the electrode area. Also, Figure 3 suggests that it is proportional to the electric potential, at least for the best working range. These results suggest that the deposition density is proportional to the electric field.Water sensitivity and field dependence indicate that two processes, electrophoresis and adherence of SWCNTs, must be considered separately. When the anode surface was covered with a polymer film or SiO 2 , no electrodeposition occurred. Similarly, we have shown here that no deposition occurs in water or wet DMF. In all cases, SWCNT aggregates were seen to move toward the anode by electrophoresis. This means that the electric field is necessary to move SWCNTs close to the anode surface, but is not sufficient to bind them. In other words, the electric field controls the aggregate concentration at the surface, but is not responsible for adhesion. Although we speculate that van der Waals' interactions are important for strong adhesion, [12] further study is necessary to clarify the binding mechanism. In summary, anhydrous conditions allow highly efficient DC deposition of SWCNTs. The process requires only a static DC electric field and freshly dispersed, straight SWCNTs. The deposited film is very uniform and tightly bound to the anode surface. This simple technique offers an alternative to CVD or printing methods for thin-film technology.

show abstract

XPS studies on strontium compounds

Cited by 98 publications

References 25 publications

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO₃ Thin‐Films Grown by Pulsed Laser Deposition

Composition and Shape Control of Crystalline Ca_1–_xSr_xTiO₃ Perovskite Nanoparticles

Contact Info

Product

Resources

About

XPS studies on strontium compounds

Cited by 98 publications

References 25 publications

High Redox Capacity of Al‐Doped La1−xSrxMnO3−δ Perovskites for Splitting CO2 and H2O at Mn‐Enriched Surfaces

High Redox Capacity of Al‐Doped La1−xSrxMnO3−δ Perovskites for Splitting CO2 and H2O at Mn‐Enriched Surfaces

Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO3 Thin‐Films Grown by Pulsed Laser Deposition

Composition and Shape Control of Crystalline Ca1–xSrxTiO3 Perovskite Nanoparticles

Contact Info

Product

Resources

About

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

High Redox Capacity of Al‐Doped La_1−xSr_xMnO_3−δ Perovskites for Splitting CO₂ and H₂O at Mn‐Enriched Surfaces

Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO₃ Thin‐Films Grown by Pulsed Laser Deposition

Composition and Shape Control of Crystalline Ca_1–_xSr_xTiO₃ Perovskite Nanoparticles