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Bocanegra‐Bernal, M.H.; Torre, S.D. De la

doi:10.1023/a:1021099308957

Cited by 194 publications

(59 citation statements)

References 78 publications

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“…[8][9][10] The excellent biocompatibility makes also zirconia a material of choice for orthopaedic prosthesis and dental restorative applications. [11][12][13][14] The above mentioned properties are typical of the tetragonal and cubic high-temperature phases: 1,12 this has stimulated a considerable effort in the characterization of the conditions determining zirconia phase stability and transition. 12,[15][16][17] The high-temperature phases can be stabilized at room temperature by introducing oxygen deficiencies; this is usually obtained by doping zirconia with divalent (Mg 2þ , Ca 2þ ) and trivalent (Y 3þ , Sc 3þ ) cationic species.…”

Section: Introductionmentioning

confidence: 99%

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

Borghi

Sogne

Lenardi

et al. 2016

Journal of Applied Physics

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Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing. [http://dx

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Section: Introductionmentioning

confidence: 99%

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

Borghi

Sogne

Lenardi

et al. 2016

Journal of Applied Physics

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“…Ceria plays multiple roles in various catalyst systems and it is believed that CeO 2 promotes noble metal dispersion, increases thermal stability of Al 2 O 3 support, promotes water gas shift (WGS) and steam reforming reactions, favors catalytic activity at the interfacial metal-support sites, promotes CO removal through oxidation by employing its lattice oxygen, stores and releases oxygen (OSC) under lean and rich conditions, and so on [4]. Therefore, CeO 2 containing materials have been receiving a great deal of attention in recent years due to their extensive use in very broad fields, ranging from catalysis [1][2][3][4][5][6][7] to ceramics [8], fuel cell technologies [9][10][11], gas sensors [12,13], solid state electrolytes [14], chromatographic materials [15], cosmetics, etc [16,17]. The technological applicability of CeO 2 -containing materials is expanding very rapidly.…”

Section: Introductionmentioning

confidence: 99%

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

2005

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The influence of SiO 2 , TiO 2 , and ZrO 2 on the structural and redox properties of CeO 2 were systematically investigated by various techniques namely, X-ray diffraction (XRD), Raman spectroscopy (RS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HREM), BET surface area, and thermogravimetry methods. The effect of supporting oxides on the crystal modification of ceria was also mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahigh dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO 2 -SiO 2 sample primarily consists of nanocrystalline CeO 2 on the amorphous SiO 2 surface. Both crystalline CeO 2 and TiO 2 -anatase phases were noted in the case of CeO 2 -TiO 2 sample. Formation of cubic Ce 0.75 Zr 0.25 O 2 and Ce 0.6 Zr 0.4 O 2 (at 1073 K) were observed in the case of CeO 2 -ZrO 2 sample. The cell 'a' parameter estimations revealed an expansion of the ceria lattice in the case of CeO 2 -TiO 2 , while a contraction is noted in the case of CeO 2 -ZrO 2 . The DRS studies suggest that the supporting oxides significantly influence the band gap energy of CeO 2 . Raman measurements disclose the presence of oxygen vacancies, lattice defects, and displacement of oxide ions from their normal lattice positions in the case of CeO 2 -TiO 2 and CeO 2 -ZrO 2 samples. The XPS studies revealed the presence of silica, titania, and zirconia in their highest oxidation states, Si(IV), Ti(IV), and Zr(IV) at the surface of the materials. Cerium is present in both Ce 4+ and Ce 3+ oxidation states. The HREM results reveal well-dispersed CeO 2 nanocrystals over the amorphous SiO 2 matrix in the case of CeO 2 -SiO 2 , isolated CeO 2 and TiO 2 (A) nanocrystals and some overlapping regions in the case of CeO 2 -TiO 2 , and nanosized CeO 2 and Ce-Zr oxides in the case of CeO 2 -ZrO 2 sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO 2 is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of mixed oxides is more than that of pure CeO 2 and the CeO 2 -ZrO 2 exhibits highest OSC.

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“…[1] In virtually all applications of zirconia, the key challenge is to control the crystal phase, morphology, and stoichiometry in order to tailor the specific targeted properties. The thermodynamically stable crystal phase of bulk zirconia is the monoclinic structure, which transforms into the tetragonal phase at 1175 8C.…”

mentioning

confidence: 99%

High‐Pressure, High‐Temperature Formation of Phase‐Pure Monoclinic Zirconia Nanocrystals Studied by Time‐Resolved in situ Synchrotron X‐Ray Diffraction

2009

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Zirconia is one of the most studied metal oxides due to the important mechanical, thermal, electrical and catalytic properties and the many applications they offer. [1] In virtually all applications of zirconia, the key challenge is to control the crystal phase, morphology, and stoichiometry in order to tailor the specific targeted properties. The thermodynamically stable crystal phase of bulk zirconia is the monoclinic structure, which transforms into the tetragonal phase at 1175 8C. The tetragonal phase can be stabilized by cation substitution, which introduces oxygen vacancies in the crystal structure. As early as 1965, Garvie suggested that the tetragonal phase of zirconia is also stabilized for nanoparticles below a critical size of 30 nm due to a lower surface energy when compared to the monoclinic phase.[2] Since then, a lot of research has been conducted to understand this phenomenon, and the many results were recently reviewed by Shukla and Seal.[3] Clearly, it is highly desirable to obtain a fundamental understanding of the formation of zirconia particles on the nanoscale, since this will allow us to design materials with improved functional properties relevant for various industrial and scientific applications. Here, we study the formation of nanocrystals by high-pressure, high-temperature time-resolved in situ X-ray diffraction under hydrothermal conditions. Our data provide striking new insight about the nucleation and formation of zirconia nanocrystals.In situ synchrotron powder X-ray diffraction has had a strong impact on materials science since the method became widely used in the 90's.[4] Many different experimental designs have been developed, for example for controlling atmospheres in studies of catalytic processes, but common for all studies is that they are not carried out under the high pressures and high temperatures needed to bring solvents into the supercritical regime. Studies of reactions in supercritical fluids necessitate highly specialized equipment to withstand the extreme conditions, while still allowing X-ray penetration. Our group recently reported the first in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) study of supercritical fluid reactions using a batch reactor, [5] and novel designs for in situ continuous-flow supercritical reactors have also been described.[6] Studying the formation and growth of zirconia nanoparticles by time-resolved in situ high-pressure, hightemperature X-ray diffraction allows a detailed and simultaneous determination of phase and size development. Zirconia nanoparticles are of particular interest during nucleation and growth due to the size-dependent crystal-phase stability. Lupo et al.

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Untitled

Cited by 194 publications

References 78 publications

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

High‐Pressure, High‐Temperature Formation of Phase‐Pure Monoclinic Zirconia Nanocrystals Studied by Time‐Resolved in situ Synchrotron X‐Ray Diffraction

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