Tetragonal zirconia powders from the zirconium n-propoxide-acetylacetone-water-isopropanol system

Guinebretière, René; Dauger, A.; André, Luc; Vesteghem, H.

doi:10.1016/s0022-3093(05)80673-8

Cited by 62 publications

(20 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By subjecting these amorphous materials to a suitable thermal treatment at relatively low temperatures, ZrO2--SiO2 glasses, fine crystalline powders, thin layers and other technological materials have been easily produced. Since the macroscopic properties of the ZrOz--SiO2 materials obtained by the sot-gel method are considerably influenced by the structural characteristics of the parent gel, a number of studies have dealt with the atomic scale structure of ZrOz--SiO2 gels (Chaumont, Craievich & Zarzycki, 1992;ltoh, 1992;Salvado & Navarro, 1990;Guinebretiere, Dauger, Lecomte & Vesteghem, 1992). However, little information exists as to the process of formation of the gels, and the coordination state and distribution of constituent Zr 4+ ions at the atomic scale.…”

Section: Introductionmentioning

confidence: 99%

Structure of ZrO₂SiO₂ Gels

Stachs¹,

Petkov²,

Gerber³

1997

J Appl Cryst

View full text Add to dashboard Cite

AbstractxZrO2(l -x)SiO2 gels have been prepared by hydrolytic polycondensation of tetraethylorthosilicate and zirconium n-propoxide in alcohol solution (x-0.1-0.5). The formation of the gels has been investigated in situ by conventional small-angle X-ray scattering. (SAXS) experiments. Primary particles of size 1-2 nm have been found in all hydrogels at the first stage of the gelation process. With further progress of the gelation, the primary particles have been found to aggregate into secondary clusters with fractal characteristics. It has also been observed that the higher the Zr concentration in the sol the faster the rate of aggregation of the primary particles. Anomalous small-angle X-ray scattering (ASAXS) and wide-angle X-ray scattering (WAXS) experiments have also been carried out on samples of ZrOz-SiO2 xerogels that have been dried only and samples that have been further heat-treated at various temperatures. The ASAXS experiments have shown that the xerogels obtained without manipulating the aggregation rate do not exhibit microinhomogeneities even when heated up to 800 K. Reverse Monte Carlo simulations based on the experimental wide-angle diffraction data have also been carried out. In line with the findings of the ASAXS experiments, the simulations have suggested that Zr and Si atomic species in the ZrOz-SiO2 xerogels investigated are homogeneously distributed at the atomic scale. The first traces of a phase segregation into Si-and Zr-rich phases, as demonstrated by the emergence of tetragonal ZrO2, were detected only after prolonged heat treatment at 1100 K.

show abstract

Section: Introductionmentioning

confidence: 99%

Structure of ZrO₂SiO₂ Gels

Stachs¹,

Petkov²,

Gerber³

1997

J Appl Cryst

View full text Add to dashboard Cite

show abstract

“…As described elsewhere (Guinebretière, Dauger, Lecomte & Vesteghem, 1992), the zirconia precursor gels were prepared in the zirconium n-propoxide, n-propanol, acetylacetone (acacH) and water system. In an air dried glove-box, the zirconium n-propoxide was diluted with n-propanol and chelated by acetylacetone.…”

Section: Methodsmentioning

confidence: 99%

“…In an air dried glove-box, the zirconium n-propoxide was diluted with n-propanol and chelated by acetylacetone. The complexing ligands are not easily hydrolysed and lead to obtain a chemical control of reactions (Guinebretière, Dauger, Lecomte & Vesteghem, 1992;Chatry, Henry & Livage, 1994) 4 ]=0.7 respectively. Gelation occurred after one month (t g =655 h) at room temperature and the gel was homogeneous, clear and transparent.…”

Section: Methodsmentioning

confidence: 99%

Dynamical scaling property of colloidal aggregation in a zirconia-based precursor sol during gelation

2000

Self Cite

View full text Add to dashboard Cite

Zirconia precursor gels, prepared in the zirconium n-propoxide, npropanol, acetylacetone and water system, are studied by small angle X-ray scattering (SAXS). The SAXS intensity pattern exhibits a pronounced maximum for a scattering vector q different from zero. The intensity maximum of the finite q-vector peak increases during gelation while its position q m moves towards smaller and smaller qvectors. The SAXS intensity distribution is well accounted for by recent direct numerical calculations of diffusion-limited cluster aggregation (DLCA). The structural aspects of cluster growth can be described by scaling assumptions. The position q m of the intensity maximum and the structure function S(q/q m ,t) are shown to scale according to S(q/q m ,t) = q m (t) -d F(q/q m ) where F(q/q m ) is a timeindependent scaling function. This scaling requires d=D f , the fractal dimension of the clusters, instead of d=3 for spinodal decomposition. The gel structure is made up of connected fractal clusters, around 50 nm in size, with an apparent fractal dimension of 1.7, resulting from the aggregation of very small primary particles about 2.5 nm in diameter.

show abstract

“…It is common to include organic chelate ligands such as acetic acid, acetylacetonate or ethylacetoacetonate to control the hydrolysis process of the Zr reactants. 40,41,42,43 Stabilized solutions can thus be formed for powder precipitation, dip-coating, spin coating, and fiber drawing fabrication methods. 44 Electrospinning of chelate-Zr precursors has also demonstrated the capability to form porous fiber mats, which can be applied in membranes, sensors, photocatalysis, photovoltaics, insulation, or as scaffolds.…”

Section: Forcespinning Of a Zirconia Shell Composition For Lmo Cathodmentioning

confidence: 99%

“…The molar ratio of acac to Zr species in this work is two, a value higher than values used in many other sol-gel fiber citations. Guinebretiere et al 43 showed that molar ratios of acac to Zr as low as 0.4 led to stable transparent solutions. A ratio of two acetylacetonate molecules to each Zr cation is used to attempt to cap the remaining alkoxide bonds.…”

mentioning

confidence: 99%

Surface engineering of electrospun fibers to optimize ion and electron transport in Li%2B battery cathodes.

Bell¹,

Missert²,

Leung³

et al. 2012

View full text Add to dashboard Cite

This report documents research into the fabrication of Lithium Manganese Oxide (Spinel) (LMO) cathode material in the form of fibrous mats, the degradation process of this material in a battery electrolyte, the formation of core-shell coated fibers and the electrochemical properties of the active cathode core fiber. In practice, LMO experiences several degradation mechanisms ranging from capacity fading, the Jahn-Teller distortion phenomenon leading to dissolution in the electrolyte phase, and the formation of surface films by degradation of the electrolyte, and/or phase transitions at the surface to form Mn 2 O 3 . Density Functional Theory (DFT) was applied to model from first principles the interactions between the electrolyte and the surface leading to Mn ion dissolution. Thermodynamic values of solvation energy were calculated and related to the applied potential on the material during electrochemical cycling. Direct in situ observation of the degradation process was conducted on fiber structures using AFM and coin cell measurements, showing the rapid formation of theorized surface films. This provides the first direct evidence of processes occurring at the interface, such as dissolution of the active material, facet development, decomposition of the electrolyte to form a surface electrolyte interface (SEI) layer, or the 4 formation of Li alcoxides/carboxylates. Methods for fabricating fiber structures of LMO were researched using two techniques; electrospinning and forcespinning. Chemical precursors were evaluated and optimized to lead to polycrystalline, hollow fibers of LMO, as well as tetragonal zirconia fiber mats. Sol-gel chemistries for the synthesis of LMO and zirconia have been implemented to generate these fiber morphologies. Core-shell methods were attempted using both techniques, proving partial success and insight into the physics of coherent core-shell fibers.The knowledge developed in this program has increased understanding of the degradation mechanisms of the active energy storage material, and aided development of a protective interface which resists these processes while permitting rapid Li + transport, good e -conductivity, a stable interface, and prevention of the formation of a solid-electrolyte interphase (SEI) layer. 5

show abstract

Tetragonal zirconia powders from the zirconium n-propoxide-acetylacetone-water-isopropanol system

Cited by 62 publications

References 6 publications

Structure of ZrO₂SiO₂ Gels

Structure of ZrO₂SiO₂ Gels

Dynamical scaling property of colloidal aggregation in a zirconia-based precursor sol during gelation

Surface engineering of electrospun fibers to optimize ion and electron transport in Li%2B battery cathodes.

Contact Info

Product

Resources

About

Tetragonal zirconia powders from the zirconium n-propoxide-acetylacetone-water-isopropanol system

Cited by 62 publications

References 6 publications

Structure of ZrO2SiO2 Gels

Structure of ZrO2SiO2 Gels

Dynamical scaling property of colloidal aggregation in a zirconia-based precursor sol during gelation

Surface engineering of electrospun fibers to optimize ion and electron transport in Li%2B battery cathodes.

Contact Info

Product

Resources

About

Structure of ZrO₂SiO₂ Gels

Structure of ZrO₂SiO₂ Gels