Phase equilibrium diagram of the system ceria-yttria for temperatures between 900 and 1700� C

Longo, Vittorio; Podda, L.

doi:10.1007/bf00552228

Cited by 14 publications

(15 citation statements)

References 1 publication

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“…6 This is in close agreement with phase equlibria in this system recently reported by us. 6 This is in close agreement with phase equlibria in this system recently reported by us.…”

Section: Introductionsupporting

confidence: 92%

Combustion synthesis of nanocrystalline yttria-doped ceria

Chavan

Tyagi

2004

J. Mater. Res.

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Nanocrystalline yttria-doped ceria powder, with the composition Ce 0.55 Y 0.45 O 1.775 , was synthesized by a combustion technique using citric acid as the fuel and the corresponding metal nitrates as oxidants. This process involves mild conditions as the external temperature required to initiate the combustion is only approximately 250°C. The product was characterized by x-ray diffraction (XRD) to ascertain the phase purity. The crystallite size of these calcined samples, as seen by transmission electron microscopy, was found to be in the range 6 nm to 50 nm. The surface area of the fine powder, as obtained from the Brunauer-Emmett-Teller technique, was about 140 m 2 /g. The agglomeration behavior as a function of temperature and the lattice thermal expansion studies were carried out using high-temperature XRD. This nanocrystalline powder resulted in nearly theoretical bulk density at a relatively lower temperature, which is attributed to the superior powder properties. The sintered microstructure, as studied by scanning electron microscopy, revealed the presence of fine grains.

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“…6 This is in close agreement with phase equlibria in this system recently reported by us. 6 This is in close agreement with phase equlibria in this system recently reported by us.…”

Section: Introductionsupporting

confidence: 92%

Combustion synthesis of nanocrystalline yttria-doped ceria

Chavan

Tyagi

2004

J. Mater. Res.

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“…However, Longo and Podda reported the existence of a two phase region [30]. Djurovic et al summarized several phase diagrams of the CeO 2 -Y 2 O 3 system reported so far [31].…”

Section: Resultsmentioning

confidence: 99%

Resistive Oxygen Sensor Using Ceria-Zirconia Sensor Material and Ceria-Yttria Temperature Compensating Material for Lean-Burn Engine

Izu

Nishizaki

Shin

et al. 2009

Sensors

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Temperature compensating materials were investigated for a resistive oxygen sensor using Ce0.9Zr0.1O2 as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y concentration in CeO2-Y2O3 was optimized. The resistance of Ce0.5Y0.5O2-δ was independent of the air-to-fuel ratio (oxygen partial pressure), so that it was confirmed to function as a temperature compensating material. Sensor elements comprised of Ce0.9Zr0.1O2 and Ce0.5Y0.5O2-δ were fabricated and the output was determined to be approximately independent of the temperature in the wide range from 773 to 1,073 K.

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“…The pure ceria and YDC particles show the same crystallographic structure of cerium oxide phase. Due to the low concentration of yttrium dopants (15 at%) (comparing to the solubility limit of 35 at% for yttrium), 10 the phase of yttria does not form in the YDC particles.…”

Section: Characterizationmentioning

confidence: 99%

“…However, in the YDC electrolytes the experimental optimum yttrium concentration (8-16 at%) 4 5 9 is * Author to whom correspondence should be addressed. much lower than the solubility limit of yttrium (35 at%) 10 in ceria. A possible reason is that above the optimum yttrium concentration, clustering of yttrium cations form domains to trap migrating oxygen ions, which decreases ion conductivity.…”

Section: Introductionmentioning

confidence: 96%

Manipulation of Dopant Distribution in Yttrium-Doped Ceria Particles

Shih¹,

Yu²,

Wu³

2012

j nanosci nanotechnol

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Yttrium is one of the most widely used dopants (e.g., in yttrium-doped ceria (YDC) and yttria-stabilized zirconia) for improving performance of solid electrolytes utilized in solid oxide fuel cells. Oxygen ion conductivity is known to be a function of yttrium concentration in the electrolytes and thus it is important to further understand the factors that influence such concentration distribution. In this study, we examine the change in the distribution of yttrium concentration after annealing in YDC particles. The geometry and morphology of YDC particles, synthesized by spray pyrolysis, were characterized using transmission electron microscopy, and the distribution of yttrium was investigated by X-ray energy-dispersive spectroscopy (XEDS) considering electron interaction volume and geometry of the particle in the XEDS profile analysis. In addition, relative concentrations of Ce(lll) ions, which are thought to be proportional to the concentrations of the oxygen vacancies in the YDC particles, were examined using X-ray photoelectron spectroscopy to correlate with yttrium concentration distributions. It was found that in the as-prepared hollow spherical particles the concentration of yttrium increases linearly from the inner surface towards the outer surface. After annealing the distribution of yttrium becomes non-linear and the dopant is found to migrate to the inner and outer surfaces of the particle. The decrease of the concentration of Ce(lll) ions upon annealing followed by the formation of the dopant concentration gradient is likely due to the increase of the size of the crystallites in the particles.

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Phase equilibrium diagram of the system ceria-yttria for temperatures between 900 and 1700� C

Cited by 14 publications

References 1 publication

Combustion synthesis of nanocrystalline yttria-doped ceria

Combustion synthesis of nanocrystalline yttria-doped ceria

Resistive Oxygen Sensor Using Ceria-Zirconia Sensor Material and Ceria-Yttria Temperature Compensating Material for Lean-Burn Engine

Manipulation of Dopant Distribution in Yttrium-Doped Ceria Particles

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