Analysis of highly resolved x‐ray photoelectron Cr 2p spectra obtained with a Cr<sub>2</sub>O<sub>3</sub> powder sample prepared with adhesive tape

Ünveren, Ercan; Kemnitz, Erhard; Hutton, Simon; Lippitz, Andreas; Unger, Wolfgang

doi:10.1002/sia.1655

Cited by 95 publications

(58 citation statements)

References 19 publications

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“…The Cr 2p 3/2 spectrum is shown for reference, at a binding energy (BE) of 573 eV. The peak positions of samples with chromium concentrations of x = 0.05 and 0.1 are quite similar to that of Cr 3+ in Cr 2 S 3, which implies that the chromium is nearly trivalent [12,13]. This proves that Cr 3+ has been successfully substituted into Ti 4+ octahedral sites in TiS 2 layers.…”

Section: Resultsmentioning

confidence: 80%

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

et al. 2013

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Abstract:A misfit layer sulfide (BiS) 1.2 (TiS 2 ) 2 with a natural superlattice structure has been shown to be a promising thermoelectric material, but its high carrier concentration should be reduced so as to further optimize the thermoelectric performance. However, ordinary acceptor doping has not succeeded because of the non-parabolic band structure. In this paper, we have successfully doped chromium ions into the Ti sites, which can maintain or even enhance the high effective mass of electrons so as to effectively improve ZT value. X-ray diffraction analysis, coupled with X-ray photoelectron spectroscopy, shows that chromium has been substituted into titanium sites in TiS 2 layers and confirms its ionic state. The chromium doping has successfully reduced the carrier concentration with the subsequent reduction of electrical conductivity. Unlike other acceptor dopants (alkaline earth metals), chromium also enhances Seebeck coefficient and the effective mass, which can possibly be attributed to the formation of additional resonant states near Fermi level. Though the power factor does not improve, the significant reduction in the electronic part of the thermal conductivity leads to a measurable improvement in ZT.

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Section: Resultsmentioning

confidence: 80%

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

et al. 2013

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“…The choice of the background subtraction method can impact the qualitative and quantitative analyses. 40,42 The 2p state of Cr(III) oxides present a multiplet splitting, caused by the interaction between 2p electrons and the unpaired 3d electrons, 41,42 therefore, Cr(III) oxide species should be represented by a multiplet splitting 43 or an asymmetric broadening peak and not by a single, symmetrical peak. 42 According to Biesinger et al 43 Cr(III) oxide shows discrete multiplet structure whereas the hydroxide shows only a broad peak shape, and a single peak is used for Cr(VI) compounds (no unpaired electrons).…”

Section: 33mentioning

confidence: 99%

“…The interpretation of the Cr2p spectrum is difficult because the binding energies of Cr(VI) and oxyfluoride of Cr(III) are very close. 12,[40][41][42][43][44][45][46] A low signal intensity at a binding energy of 579.8 eV can be observed so the presence of hexavalent chromium in the craters cannot be ruled out. It is possible to calculate the maximum quantity of Cr(VI) present at different depths of the layer (in each crater), and therefore calculate the maximum quantity of Cr(VI), which could be present in the TCP layer after PACS post-treatment.…”

Section: 33mentioning

confidence: 99%

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Ely

Światowska

Seyeux

et al. 2017

J. Electrochem. Soc.

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The effects of post-treatment applied on Trivalent Chromium Protection (TCP) coatings deposited on aluminum alloy 2024-T3 was studied by electrochemical and surface analytical techniques: X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The aim of the post-treatment was to improve the corrosion resistance of the TCP coating. To understand the influence of the post-treatment, using a bath containing H 2 O 2 and a lanthanum salt as an inhibitor, our approach was to study the effect of these two components separately. It was found that the improved corrosion protection provided by the post-treated TCP was related to a synergetic effect of the two components. XPS and ToF-SIMS analyses showed that (i) the thickness of the TCP coating is not modified by the post-treatment, (ii) lanthanum is present on the surface and in the bulk of the TCP and (iii) is found in very small amount only on the extreme surface. The total concentration of Cr(VI) (oxide/hydroxide) was estimated to be below 0.1 wt% in the post-treated TCP layer. It was concluded that lanthanum plays a significant role in improving the coating density and homogeneity and has a beneficial effect on the TCP coating cracking as observed by Scanning Electron Aluminum alloys are used for aerospace applications for their low weight and good mechanical properties.1-3 To improve the corrosion properties of aluminum alloys and to provide good paint adhesion, the first layer of coating applied on the aluminum alloy surface used to be a chromate conversion coating (CCC).4-6 However, hexavalent chromium used in the CCC coatings is highly toxic, 4,7 its use is very much restricted in Europe 8 and the United States 9 and will be forbidden by 2024 by the European Community with respect to the Registration, Evaluation, Authorization and Restriction of Chemicals (REACh).8 Therefore, new conversion coatings have been developed, and one of the most promising solutions is the Trivalent Chromium Protection coating called also as the Trivalent Chrome Process (TCP).10-14 TCP conversion coatings are formed by immersion in a solution containing Zr 4+ , Cr 3+ and F − ions, at a pH between 3.8 and 4.0. As it has already been widely discussed, the coating formation mechanism occurs by multiple chemical steps. 10,11,13,[15][16][17] The initial step involves dissolution of the aluminum oxide layer by fluorides. The removal of the oxide layer exposes the metal surface where cathodic reactions take place. Oxygen reduction reaction, and possibly hydrogen discharge, which counterbalance aluminum oxidation, consume protons and causes a pH increase at the interface between the metallic substrate and the solution, as measured by Li et al. 15 The high pH favors the precipitation of ions present in the solution, forming a hydrated layer of zirconium and chromium oxide. The thickness of the TCP layer is usually of the order of 100 nm, depending on the nature of the aluminum alloy, the concentration of the solution and the immersion time.11,12,18 ...

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“…Indeed, it has been calculated that 65 multiplet peaks exist in XPS 2p spectra of Cr(III) species [23]. However, experimentally, these multiplets appear as bundles of peaks (typically five for the 2p 3/2 peak), which must be fit with varying FWHM values and peak heights to allow for electron coupling, as well as variances in the lifetime broadening [24]. In the prior work [7], SEM images of increased bundle size were suggested as being an indicator of interconnects, i.e., Cr(SWCNT) 2 .…”

Section: Reaction Of Group 6 Complexes With Raw Swcntsmentioning

confidence: 99%

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

Wright

Barron

2017

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Abstract:The reaction of Group 6 metals with SWCNT has the potential to bridge the resistive SWCNT . . . SWCNT junctions by the formation of "Cr(SWCNT) 2 " complexes analogous to Cr(C 6 H 6 ) 2 . This study reports that the formation of such species is very sensitive to oxidation by a residual iron oxide catalyst used for the growth of the SWCNTs and adsorbed/bound oxygen functionality. The reaction of raw HiPco SWCNTs with M(CO) 6 and (C 7 H 8 )M(CO) 3 (M = Cr, W) or (C 6 H 6 )Cr(CO) 3 results in the formation of the Group 6 metal oxides. Annealing and acid treating the HiPco SWCNTs to reduce the catalyst content allows for the observation of zero valent metals by XPS, while the use of very high purity SWCNTs and graphene allows for the addition of primarily zero valent Group 6 metals, including the bis-hexahapto metal complex.

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Analysis of highly resolved x‐ray photoelectron Cr 2p spectra obtained with a Cr₂O₃ powder sample prepared with adhesive tape

Cited by 95 publications

References 19 publications

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

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Analysis of highly resolved x‐ray photoelectron Cr 2p spectra obtained with a Cr2O3 powder sample prepared with adhesive tape

Cited by 95 publications

References 19 publications

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

Thermoelectric performance enhancement of (BiS)1.2(TiS2)2 misfit layer sulfide by chromium doping

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Catalyst Residue and Oxygen Species Inhibition of the Formation of Hexahapto-Metal Complexes of Group 6 Metals on Single-Walled Carbon Nanotubes

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Analysis of highly resolved x‐ray photoelectron Cr 2p spectra obtained with a Cr₂O₃ powder sample prepared with adhesive tape