XPS study of the interface reactions between buffer layers for HTSC thin films and silicon

Behner, H.; Wecker, J.; Matthée, Th.; Samwer, K.

doi:10.1002/sia.740180909

Cited by 47 publications

(21 citation statements)

References 11 publications

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“…The unsupported Ce-Zr mixed oxides with the combination of Ce 0.75 Zr 0.25 O 2 and Ce 0.5 Zr 0.5 O 2 phases having the crystallite size of ∼10 nm exhibited 50% conversion at a temperature of 633 K [23], while the silica stabilized Ce-Zr-oxides of below 5 nm (present study) indicate a temperature of 545 K for the same conversion with slightly better product distribution, which is intriguing. The decrease of temperature corresponding to 50% conversion could be attributed to the reduced crystallite size of the Ce-Zr-oxides, which exhibit increased reactivity due to very small size.…”

Section: Resultsmentioning

confidence: 59%

“…This involves three types of mechanisms viz., concerted elimination pathway (E2), formation of carbocation (E1) and carbanion formation via two-point mechanism (E1cB) [22,23]. These mechanisms should be regarded as limiting cases, since intermediate situations can occur.…”

Section: Resultsmentioning

confidence: 99%

“…Fig. 4 displays the Ce 3d spectra of the CZ/S sample [17,22] and other inert compounds such as CeSiO 4 and ZrSiO 4 which can be identified with the Si 2p binding energy value at 101 eV [17,23]. The notation of Burroughs et al [24] as envisaged in the literature, could be used to elucidate the Ce 3d peaks as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Dehydration of 4-methylpentan-2-ol over CexZr1−xO2/SiO2 nano-composite catalyst

Reddy

Lakshmanan

Bharali

et al. 2006

Journal of Molecular Catalysis A: Chemical

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Section: Resultsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

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Dehydration of 4-methylpentan-2-ol over CexZr1−xO2/SiO2 nano-composite catalyst

Reddy

Lakshmanan

Bharali

et al. 2006

Journal of Molecular Catalysis A: Chemical

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“…occurs together with partial oxidation of Si. The formation of either CeSiO 4 or ZrSiO 4 could be identified by the Si 2p binding energy value of 101 eV and clearly these are absent [88]. The Ti 2p photoelectron spectra of the CZT samples exhibited typical XPS peaks in the range of 458.5-458.8 eV for Ti 2p 3/2 [89,90].…”

Section: Xps Analysismentioning

confidence: 97%

Highly Dispersed Ce x Zr1−x O2 Nano-Oxides Over Alumina, Silica and Titania Supports for Catalytic Applications

2008

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We have been exploring the utilization of supported ceria and ceria-zirconia nano-oxides for different catalytic applications. In this comprehensive investigation, a series of Ce x Zr 1-x O composite oxide catalysts were synthesized and subjected to thermal treatments from 773 to 1073 K to examine the influence of support on thermal stability, textural properties and catalytic activity of the ceria-zirconia solid solutions. The physicochemical characterization studies were performed using X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HREM), thermogravimetry and BET surface area methods. To evaluate the catalytic properties, oxygen storage/release capacity (OSC) and CO oxidation activity measurements were carried out. The XRD analyses revealed the formation of Ce 0.75 Zr 0.25 O 2 , Ce 0.6 Zr 0.4 O 2 , Ce 0.16 Zr 0.84 O 2 and Ce 0.5 Zr 0.5 O 2 phases depending on the nature of support and calcination temperature employed. Raman spectroscopy measurements in corroboration with XRD results suggested enrichment of zirconium in the Ce x Zr 1-x O 2 solid solutions with increasing calcination temperature thereby resulting in the formation of oxygen vacancies, lattice defects and oxygen ion displacement from the ideal cubic lattice positions. The HREM results indicated a well-dispersed cubic Ce x Zr 1-x O 2 phase of the size around 5 nm over all supports at 773 K and there was no appreciable increase in the size after treatment at 1073 K. The XPS studies revealed the presence of cerium in both Ce 4? and Ce 3? oxidation states in different proportions depending on the nature of support and the treatment temperature applied. All characterization techniques indicated absence of pure ZrO 2 and crystalline inactive phases between Ce-Al, Ce-Si and Ce-Ti oxides. Among the three supports employed, silica was found to stabilize more effectively the nanosized Ce x Zr 1-x O 2 oxides by retarding the sintering phenomenon during high temperature treatments, followed by alumina and titania. Interestingly, the alumina supported samples exhibited highest OSC and CO oxidation activity followed by titania and silica. Details of these findings are consolidated in this review.

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“…occurs together with partial oxidation of Si. The formation CeSiO 4 could be identified by the Si 2p binding energy value of 101 eV and clearly these are absent [93]. As shown in Table 3 and Fig.…”

Section: Xps Measurementsmentioning

confidence: 97%

A Rapid Microwave-Induced Solution Combustion Synthesis of Ceria-Based Mixed Oxides for Catalytic Applications

2009

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We have been exploring the utilization of a simple and fast microwave-induced solution combustion synthesis technique for the preparation of various ceriabased mixed oxides for different catalytic applications. In our comprehensive investigation, CeO 2 -SiO 2 (MWCS), CeO 2 -TiO 2 (MWCT), CeO 2 -ZrO 2 (MWCZ) and CeO 2 -Al 2 O 3 (MWCA) mixed oxides were synthesized by solution combustion synthesis method using microwave dielectric heating and employed for CO and soot oxidation applications. The intricate relationship between ceria and other supporting oxides has been explored with the help of various analytical techniques namely, X-ray diffraction (XRD), temperature programmed reduction/oxidation (TPR/TPO), temperature programmed desorption (TPD) of ammonia and CO 2 , Raman spectroscopy (RS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), BET surface area and thermogravimetry analysis (TGA) methods. XRD results revealed amorphous nature of the material in case of ceria-silica mixed oxide and formation of a specific cubic fluorite type Ce 0.5 Zr 0.5 O 2 solid solution in the case of ceria-zirconia mixed oxide. Ceria-titania and ceria-alumina mixed oxides exhibited diffraction lines only due to crystalline ceria. Zirconia-based mixed oxide exhibited a lower reduction temperature and better redox properties compared to other samples. TPD of ammonia and CO 2 results revealed superior acid-base properties for MWCS mixed oxide.TGA measurements indicated a complete combustion in all preparations. RS results suggested defective structure of mixed oxides resulting in the formation of oxygen vacancies. XPS results revealed that ceria-zirconia mixed oxide contained more Ce 3? compared to other oxides. Among all the mixed oxides, the MWCZ sample exhibited a higher oxygen storage capacity, and better CO and soot oxidation activities. All these interesting findings have been elaborated in this publication.

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XPS study of the interface reactions between buffer layers for HTSC thin films and silicon

Cited by 47 publications

References 11 publications

Dehydration of 4-methylpentan-2-ol over CexZr1−xO2/SiO2 nano-composite catalyst

Dehydration of 4-methylpentan-2-ol over CexZr1−xO2/SiO2 nano-composite catalyst

Highly Dispersed Ce x Zr1−x O2 Nano-Oxides Over Alumina, Silica and Titania Supports for Catalytic Applications

A Rapid Microwave-Induced Solution Combustion Synthesis of Ceria-Based Mixed Oxides for Catalytic Applications

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