Structural and compositional characterization of laser ablated CeO2 thin films

Sánchez, F.; Várela, M.; Ferrater, C.; Garcı́a-Cuenca, M.V.; Aguiar, R.; Morenza, J.L.

doi:10.1016/0169-4332(93)90405-z

Cited by 18 publications

(7 citation statements)

References 10 publications

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“…However, the poor intensity of the spectra with large peak widths indicated that SiO 2 is not easily accessible at the surface due to the presence of Ce-Zr-oxide over-layers. The presence of oxidized silicon has been abundantly described in the literature, sometimes as CeO 2-x /SiO 2 [84,85] or as an amorphous silicate layer [86,87], where partial reduction of Ce 4? to Ce 3?…”

Section: Xps Analysismentioning

confidence: 99%

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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Section: Xps Analysismentioning

confidence: 99%

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

2008

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“…x /SiO 2 [89,90] or as an amorphous silicate layer [91,92], where partial reduction of Ce 4? to Ce 3?…”

Section: Xps Measurementsmentioning

confidence: 99%

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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“…This result is quite different to that observed on other semiconductor substrates such as Si and GaAs, in which a significant reactivity with Ce has been reported. 19,20 The minor chemical influence of the substrate on the film could also explain the independence of the CeO 2 properties on the substrate surface. This result suggests that the main parameter controlling the CeO 2 film orientation would be the lattice mismatch between CeO 2 and InP.…”

Section: Discussionmentioning

confidence: 99%

“…Particularly, on ͑111͒Si epitaxial ͗111͘CeO 2 has been achieved, 16,17 while the CeO 2 film properties on ͑100͒Si are determined by the surface preparation: CeO 2 grows as ͗110͘CeO 2 //͗100͘Si on bare ͑100͒Si and ͓111͔-textured on the oxidized SiO 2 /͑100͒Si surface. 18,19 Only few papers are related to the CeO 2 deposition on the direct band gap semiconductors, likely due to the lattice match and chemical reactivity which often lead to nonoptimized CeO 2 deposits, like on ͑100͒GaAs. 20 In this article, we report on the pulsed laser deposition conditions leading to PLT/CeO 2 /͑100͒InP multilayers with oriented and crystalline structures as well as on the morphology of the films obtained.…”

Section: Introductionmentioning

confidence: 99%

Integration of piezoelectric (Pb, La)TiO3 on (100)InP by using a CeO2 buffer layer

Vasco

Vázquez

Zaldo

et al. 2001

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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(Pb, La)TiO 3 /CeO 2 /(100)InP multilayers have been prepared by pulsed laser deposition (PLD) using a KrF laser. CeO2 films deposited in a low oxygen pressure (PO2=10−5 mbar) exhibit the coexistence of stoichiometric CeO2 and oxygen deficient CeO2−x phases. The latter can be best avoided by a postdeposition annealing in a higher oxygen pressure (PO2=0.1 mbar). The PLD conditions leading to largest grain size and [111] textured CeO2 are a substrate temperature Ts=575 °C and a laser fluence of 4 J/cm2. (Pb, La)TiO3 films are deposited at Ts=650 °C and PO2=0.1 mbar. The CeO2 buffer stimulates [001] (Pb, La)TiO3 texture. The films have sharp layer interfaces and uniform composition inside their respective layers.

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Structural and compositional characterization of laser ablated CeO2 thin films

Cited by 18 publications

References 10 publications

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

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

Integration of piezoelectric (Pb, La)TiO3 on (100)InP by using a CeO2 buffer layer

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