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Hay, J. N.; Raval, Hema M.

doi:10.1023/a:1008615708489

Cited by 57 publications

(22 citation statements)

References 9 publications

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“…One such method is the non-hydrolytic sol gel (NHSG) process, which was shown to provide an elegant route to mixed metal oxides [60,61,62,63,64]. It was previously demonstrated that this chemistry can be applied to the synthesis of A 2 M 3 O 12 compounds.…”

Section: Introductionmentioning

confidence: 99%

Low Temperature Synthesis and Characterization of AlScMo3O12

et al. 2015

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Recent interest in low and negative thermal expansion materials has led to significant research on compounds that exhibit this property, much of which has targeted the A2M3O12 family (A = trivalent cation, M = Mo, W). The expansion and phase transition behavior in this family can be tuned through the choice of the metals incorporated into the structure. An undesired phase transition to a monoclinic structure with large positive expansion can be suppressed in some solid solutions by substituting the A-site by a mixture of two cations. One such material, AlScMo3O12, was successfully synthesized using non-hydrolytic sol-gel chemistry. Depending on the reaction conditions, phase separation into Al2Mo3O12 and Sc2Mo3O12 or single-phase AlScMo3O12 could be obtained. Optimized conditions for the reproducible synthesis of stoichiometric, homogeneous AlScMo3O12 were established. High resolution synchrotron diffraction experiments were carried out to confirm whether samples were homogeneous and to estimate the Al:Sc ratio through Rietveld refinement and Vegard’s law. Single-phase samples were found to adopt the orthorhombic Sc2W3O12 structure at 100 to 460 K. In contrast to all previously-reported A2M3O12 compositions, AlScMo3O12 exhibited positive thermal expansion along all unit cell axes instead of contraction along one or two axes, with expansion coefficients (200–460 K) of αa = 1.7 × 10−6 K−1, αb = 6.2 × 10−6 K−1, αc = 2.9 × 10−6 K−1 and αV = 10.8 × 10−6 K−1, respectively.

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Section: Introductionmentioning

confidence: 99%

Low Temperature Synthesis and Characterization of AlScMo3O12

et al. 2015

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“…Heterogenization of the metallocenes was performed together with the SiO 2 synthesis, which was carried out according to a nonhydrolytic sol-gel route based on the studies of Hay and Haval [19] and Bourget et al [20] However, modifications were done in order to avoid metallocene deactivation. Scheme 1 shows the synthetic route used in this study.…”

Section: Catalysts Synthesismentioning

confidence: 99%

Direct production of ultra-high molecular weight polyethylene with oriented crystalline microstructures

Fisch

Silveira

Cardozo

et al. 2013

Journal of Molecular Catalysis A: Chemical

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“…[17,18] However, modifications were done due to thermal liability of the metallocenes, for instance. Scheme 1 shows the routes evaluated in this study.…”

Section: Metallocene Encapsulationmentioning

confidence: 99%

Immobilization of Zirconocene into Silica Prepared by Non‐Hydrolytic Sol‐Gel Method

Fisch

Petry

Pozebon

et al. 2006

Macromolecular Symposia

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Summary: Concomitant immobilization of zirconocene (Cp 2 ZrCl 2 ) into a silica matrix was performed during the SiO 2 synthesis through non-hydrolytic sol-gel method. Two different routes, varying the SiCl 4 :Si(OEt) 4 ratio were evaluated in terms of zirconocene content and catalyst activity in ethylene polymerization, using methylaluminoxane (MAO) as cocatalyst. The catalysts were characterized by Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy and X-ray dispersive spectroscopy. The zirconocene content laid between 0.60 and 1.02 wt.% Zr/SiO 2 , depending upon the components ratio employed in the sol-gel synthesis. Catalyst grains presented of irregular shape (20-100 mm size) and zirconocene distribution was not uniform. Both routes led to supported catalysts active in ethylene polymerization. Catalyst activity was intermediate between that exhibited by the homogeneous and the grafted zirconocene on silica. Resulting polyethylenes presented narrow molecular weight distribution and molecular weight slightly higher than that observed in the case of polymer produced with the homogeneous system.

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Cited by 57 publications

References 9 publications

Low Temperature Synthesis and Characterization of AlScMo3O12

Low Temperature Synthesis and Characterization of AlScMo3O12

Direct production of ultra-high molecular weight polyethylene with oriented crystalline microstructures

Immobilization of Zirconocene into Silica Prepared by Non‐Hydrolytic Sol‐Gel Method

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