Crystal structure of pure ZrO2 nanopowders

Lamas, Diego G.; Rosso, Aldana; Anzorena, M. Suarez; Fernández, A.; Bellino, Martín G.; Cabezas, Marcelo D.; Reca, N.E. Walsöe de; Craievich, A. F.

doi:10.1016/j.scriptamat.2006.05.035

Cited by 73 publications

(61 citation statements)

References 18 publications

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“…Recently, Lamas et al [20] pointed out that the tetragonal phase identity of ZrO 2 nanocrystallites can be verifi ed by observing the splitting of the (400) line of the fl uorite-like ZrO 2 structure into (004) and (400) lines of the tetragonal phase with more than one degree of separation in their XRD studies. Moreover, the intensity of the (112) Bragg peak should disappear for the cubic phase, but not for the tetragonal phase ZrO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Thermal stability of nanostructurally stabilized zirconium oxide

Namavar¹,

Wang

Cheung

et al. 2007

Nanotechnology

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Nanostructurally stabilized zirconium oxide (NSZ) hard transparent films were produced without chemical stabilizers by the ion beam assisted deposition technique (IBAD). A transmission electron microscopy study of the samples produced below 150 °C revealed that these films are composed of zirconium oxide (ZrO2) nanocrystallites of diameters 7.5 ± 2.3 nm. X-ray and selected-area electron diffraction studies suggested that the as-deposited films are consistent with cubic phase ZrO2. Rutherford backscattering spectroscopy (RBS) indicated the formation of stoichiometric ZrO2. The phase identity of these optically transparent NSZ films was in agreement with cubic ZrO2, as indicated by the matching elastic modulus values from the calculated results for pure cubic zirconium oxide and results of nanoindentation measurements. Upon annealing in air for 1 h, these NSZ films were found to retain most of their room temperature deposited cubic phase x-ray diffraction signature up to 850 °C. Size effect and vacancy stabilization mechanisms and the IBAD technique are discussed to explain the present results.

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Section: Resultsmentioning

confidence: 99%

“…Tetragonal phase of ZrO 2 powder has also been reported in the nanocrystalline phase with larger particle sizes [18][19][20]. Thermal stability studies of metastable tetragonal phase ZrO 2 synthesized via the sol-gel method report that these materials revert to monoclinic phase upon heating above 300 °C [21] or even above 400 °C [22].…”

Section: Introductionmentioning

confidence: 96%

Thermal stability of nanostructurally stabilized zirconium oxide

Namavar¹,

Wang

Cheung

et al. 2007

Nanotechnology

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“…To date, most research has focused on radiation processes (primarily heavy ion irradiation) in either partially-or fully stabilized zirconia as single crystals or with micron-sized grains, or on nanograined ZrO 2 that are either embedded in a foreign matrix or as free-standing particles [15][16][17]. The work presented here examines the effect of heavy ion irradiation on NSZ with a view to understanding the defect production, saturation and evolution of oxygen vacancies, and how this impacts the unit cell structure.…”

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confidence: 99%

Lattice distortions and oxygen vacancies produced in Au+-irradiated nanocrystalline cubic zirconia

et al. 2011

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“…For the 700 ºC annealed sample a weak peak corresponding to the main line of the monoclinic ZrO 2 structure can be observed at 2θ ≈ 28º, its intensity decreasing after the annealing at 900 ºC. Although it has been argued that a critical crystallite size exists for reversion to the stable monoclinic phase [2], useful information on the grain size could not be extracted from the present XRD data. The PALS lifetime spectra were decomposed into three exponential decays, each positron state being characterized by a positron lifetime τ i  , of intensity I i .…”

mentioning

confidence: 72%

“…Three equilibrium polymorphs are known for pure zirconia: monoclinic (up to 1200 ºC), tetragonal (up to 2400 ºC) and cubic (up to melting point) [1,2]. One of the main objectives in zirconia ceramics research is the stabilization of the tetragonal phase at RT, often achieved by the addition of a trivalent oxide as Y 2 O 3 is.…”

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confidence: 99%

Positron characterization of metastable phases in yttria stabilized zirconia

Damonte

Caracóche²,

Lamas

2007

Phys. Status Solidi (c)

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The thermal evolution of positron annihilation parameters in nanosized 10 mol % Y 2 O 3 doped ZrO 2 powders is presented. Three positron lifetimes have been determined up to 900 ºC annealing temperature. The two major ones have been interpreted, one as a mean between positron annihilation in the bulk and in vacancy-like open volume defects and the other, as due to annihilation in higher sized volume defects. The intensity ratio between the two defect structures depends on temperature and could be reflecting the thermal t"-to cubic metastable transformation known to occur in the studied system.1 Introduction Zirconia-based ceramic systems have been widely studied due to their excellent mechanical and electrical properties. Three equilibrium polymorphs are known for pure zirconia: monoclinic (up to 1200 ºC), tetragonal (up to 2400 ºC) and cubic (up to melting point) [1,2]. One of the main objectives in zirconia ceramics research is the stabilization of the tetragonal phase at RT, often achieved by the addition of a trivalent oxide as Y 2 O 3 is. As this situation provokes a certain amount of oxygen vacancies in the ZrO 2 host lattice for charge balance, the characterization and identification of the generated defects becomes most relevant since the electrical properties of yttria doped zirconias (YSZ) depend on the defect structure. Positron annihilation spectroscopy has proved to be an excellent tool for defect identification [3,4]. In particular, it was applied to the study of generated defects in ZrO 2 oxides upon doping with different trivalent oxides [5][6][7]. In the present work we present PALS results obtained on a 10 mol % Y 2 O 3 -stabilized ZrO 2 system (10YSZ) whose hyperfine interaction had been already determined [1]. The nanocrystalline powder synthesized by a nitrate-citrate gel-combustion process and stabilized in the metastable t"-form of the tetragonal phase, was characterized at the nanoscopic level using mainly the Perturbed Angular Correlations technique. Oxygen vacancy movement is revealed as a slow diffusion process involving a very small activation energy. As the powder was heated, a t"-to-cubic transformation occurred around 600 °C. Here, the evolution of the positron annihilation parameters with annealing temperature is analyzed in order to determine the existing different defect structures and correlate them with the phase evolution observed by PAC.

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Crystal structure of pure ZrO2 nanopowders

Cited by 73 publications

References 18 publications

Thermal stability of nanostructurally stabilized zirconium oxide

Thermal stability of nanostructurally stabilized zirconium oxide

Lattice distortions and oxygen vacancies produced in Au+-irradiated nanocrystalline cubic zirconia

Positron characterization of metastable phases in yttria stabilized zirconia

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