Yttria stabilized zirconia synthesis in supercritical CO2: Understanding of particle formation mechanisms in CO2/co-solvent systems

Hertz, Audrey; Corre, Yves-Marie; Sarrade, S.; Guizard, C.; Julbe, A.; Ruiz, Jean-Christophe; Fournel, Bruno

doi:10.1016/j.jeurceramsoc.2010.01.021

Cited by 12 publications

(10 citation statements)

References 17 publications

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“…As detailed in a previous article [14] the decrease of SC-CO 2 density when temperature increases, and the associated increase of self-diffusion coefficients for nanoparticles and/or reacting species, favor reaction kinetics and crystallite growth. Crystallite growth seems to be heterogeneous at 350 °C, certainly due to multi-step precipitation during the temperature rise step in the reactor [16], yielding a wide (bimodal) particle size distribution for #P350 with maxima at ~ 15 and 35 nm.…”

Section: Morphology and Microstructurementioning

confidence: 99%

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

et al. 2020

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Nuclear facilities generate contaminated effluents containing radionuclides (such as Cs, Sr, Co…) that need to be removed for human health and environment protection reasons. Inorganic sorbents are attractive candidate materials because of their high thermochemical and radiation stability. Furthermore, their microstructural and surface properties can be adjusted to increase the radionuclide extraction efficiency. In this study, nanostructured sorbents consisting of aggregated TiO 2 nanocrystals with different surface properties and microstructures were prepared in supercritical CO 2 by varying the synthesis temperature. The Sr 2+ sorption process was characterized by measuring the surface properties and extraction capacity of the samples as a function of pH. In basic effluents, the Sr sorption capacity of these materials is directly linked to their specific surface area and sorption site density through a classic physisorption mechanism. Sr 2+ diffusion into the mesopores leads to rapid initial sorption, which is followed by a slower process driven by a proposed multistep mechanism. This mechanism involves the initial adsorption of partially hydrated Sr 2+ ions up to complete TiO 2 surface coverage, which implies slower Sr ion diffusion due to steric hindrance in small mesopores thus limiting access to additional secondary sites with lower adsorption energies.kinetics. Mesoporous powders with a high surface to volume ratio are beneficial because the active sites are easily accessible. Adsorption performance also seems to depend on the organization of the active sites and therefore on the crystalline structure of the sorbent [11]. Synthesizing nanostructured anatase TiO 2 with a high surface area and a well-defined mesoporous network would thus be a key advance for sorption-based decontamination processes.The TiO 2 sorbents investigated here were synthesized using supercritical carbon dioxide (SC-CO 2 ) as the reaction solvent, which has been shown to offer several advantages for the preparation and processing of inorganic nanostructured materials (nanopowders, thin films, impregnation of catalysts…) [12,13]. The unique diffusion properties and solvent power of SC-CO 2 allow mesoporous anatase powders with a high specific area to be prepared at low temperatures without any surfactant [14]. The density of the CO 2 is known to be a crucial parameter in controlling the particle size and morphology of metal oxides synthesized in SC-CO 2 [15]. In this study, TiO 2 particles were synthesized at a fixed pressure (~ 300 bar) and the effect of the SC-CO 2 temperature was investigated on their size, morphology, microstructure, surface properties, and the nature and density of the sorption sites. The adsorption mechanism and Sr 2+ extraction efficiency of these materials were then investigated at different pHs and correlated with their microstructure and surface properties. Finally, the Sr sorption properties of the particles (kinetics, isotherms, maximum capacity, distribution coefficient, and thermodynamic sorption constan...

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Section: Morphology and Microstructurementioning

confidence: 99%

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

et al. 2020

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“…In previous works, the authors synthesized crystalline zirconia from metal-organic precursors in SC-CO2 by applying high synthesis temperatures directly in the reactor [50][51][52][53]. Zirconia crystallisation was attained under supercritical conditions at lower temperatures compared to conventional sol-gel and thermal treatment protocols.…”

Section: Direct Synthesis Of Nanocrystalline Tio2 Anatase Powder In S...mentioning

confidence: 99%

A detailed insight into the preparation of nanocrystalline TiO2 powders in supercritical carbon dioxide

et al. 2017

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This work reports detailed investigations for the preparation of nanostructured titania powders by a solvent-free sol-gel derived process, operated in supercritical CO2 (SC-CO2) at high pressures (10 -30 MPa) and large range of temperatures (373 K -823 K).Depending on the processing temperature, the reaction between Ti(OiPr)4 and water performed in a single supercritical phase led to the formation of either amorphous (Ti(OH)4 -Titanium hydroxide) or crystalline (TiO2 -Titania or Titanium dioxide) nanostructured particles. Crystalline (anatase) mesoporous powders with high specific surface area were obtained directly in CO2 solvent under supercritical conditions at temperatures as low as 523 K. The effect of hydrodynamic key process parameters such as stirring and water injection rate on both powder morphology and aggregation degree was also investigated in details. The optimized TiO2 anatase powders exhibited attractive photocatalytic activity, with high potential for the degradation of water pollutants.

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“…This work relies on the use of a supercritical route that was developed in previous works. 31 The original route was optimized to elaborate tetragonal zirconia polycrystal (Y-TZP) with 4% mol of Y 2 O 3 . Using pentane as a co-solvent for the reactants solubilization, 50–250 nm wide particles constituted with 15–30 nm crystallites were obtained.…”

Section: Introductionmentioning

confidence: 99%

Yttria-stabilized zirconia (8YSZ) synthesis in a supercritical CO₂-assisted process: a parametric study for achieving cubic phase stability

Avédikian,

Vulliet,

David

et al. 2024

New J. Chem.

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Yttria stabilized zirconia synthesis in supercritical CO2: Understanding of particle formation mechanisms in CO2/co-solvent systems

Cited by 12 publications

References 17 publications

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

A detailed insight into the preparation of nanocrystalline TiO2 powders in supercritical carbon dioxide

Yttria-stabilized zirconia (8YSZ) synthesis in a supercritical CO₂-assisted process: a parametric study for achieving cubic phase stability

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Yttria stabilized zirconia synthesis in supercritical CO2: Understanding of particle formation mechanisms in CO2/co-solvent systems

Cited by 12 publications

References 17 publications

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

Investigation of the surface properties and microstructure of TiO2 sorbents prepared in supercritical CO2 for the treatment of Sr2+ contaminated effluents

A detailed insight into the preparation of nanocrystalline TiO2 powders in supercritical carbon dioxide

Yttria-stabilized zirconia (8YSZ) synthesis in a supercritical CO2-assisted process: a parametric study for achieving cubic phase stability

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Yttria-stabilized zirconia (8YSZ) synthesis in a supercritical CO₂-assisted process: a parametric study for achieving cubic phase stability