Raman and infrared spectra on silica gel evolving toward glass

Bertoluzza, A.; Fagnano, C.; Morelli, Massimo; Gottardi, V.; Guglielmi, Massimo

doi:10.1016/0022-3093(82)90250-2

Cited by 608 publications

(340 citation statements)

References 35 publications

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“…[15,48] Upon calcination, the band ascribed to the Si-O-Si asymmetric stretching is shifted to a lower wavenumber, 1066 cm -1 . [18,49,50] A further band at 450 cm -1 was also detected, which has been ascribed by other authors to the vibrations of the Si-O-Si network. [8] All vibrations typical of the organic components of the matrix could be detected in the as-prepared samples.…”

Section: Resultssupporting

confidence: 65%

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Armelao

Bertagnolli

Bleiner

et al. 2007

Adv Funct Materials

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ZrO2 and HfO2 nanoparticles are homogeneously dispersed in SiO2 matrices (supported film and bulk powders) by copolymerization of two oxozirconium and oxohafnium clusters (M4O2(OMc)12, M = Zr, Hf; OMc = OC(O)–C(CH3)CH2) with (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH2C(CH3)C(O)O)–(CH2)3Si(OCH3)3). After calcination (at a temperature ≥800 °C), a silica matrix with homogeneously distributed MO2 nanocrystallites is obtained. This route yields a spatially homogeneous dispersion of the metal precursors inside the silica matrix, which is maintained during calcination. The composition of the films and the powders is studied before and after calcination by using Fourier transform infrared (FTIR) analysis, X‐ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS). The local environment of the metal atoms in one of the calcined samples is investigated by using X‐ray Absorption Fine Structure (XAFS) spectroscopy. Through X‐ray diffraction (XRD) the crystallization of Hf and Zr oxides is seen at temperatures higher than those expected for the pure oxides, and transmission electron microscopy (TEM) shows the presence of well‐distributed and isolated crystalline oxide nanoparticles (5–10 nm).

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Section: Resultssupporting

confidence: 65%

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Armelao

Bertagnolli

Bleiner

et al. 2007

Adv Funct Materials

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“…They can be assigned to the asymmetric stretching [41,42], symmetric stretching [42,43] and its bending rocking mode vibration of the Si-O-Si network [42,[44][45][46], respectively.…”

Section: Ft-ir Spectramentioning

confidence: 99%

Pore ordering in mesoporous matrices induced by different directing agents

et al. 2014

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Mesoporous silica particles of MCM-41 type were synthesized by sol-gel method from tetraethyl orthosilicate (TEOS) in 2-methoxyethanol and deionized water mixture in base conditions at room temperature. Ammonia or sodium hydroxides were used as catalysts and cetyl-trimethylammonium bromide (CTAB) and n-dodecyl-trimethylammonium bromide (DTAB) as structure directing agents. The porosities and the ordered structure have been analyzed using transmission and scanning electron microscopy, small angle neutron and Xray diffraction, nitrogen adsorption, thermal analysis and FTIR spectroscopy. The samples consist of spherical particles of sub-micrometer size, with radially arranged pores. The comparison of the effect of the different surfactants and catalysts shows that by varying the surfactant type and their proportion, the pore sizes can be controlled. As compared to the commonly used ammonia catalyst, the use of NaOH as catalyst results in a much smaller porosity of the as-prepared materials. These materials are not resisting to the heat treatment at 700 ºC used for the template removal, and the ordered porous structure is completely lost.

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“…The SiO 2 forces AlO 6 in boehmite to AlO 4 polyhedron. 23) The peak at 730760 cm ¹1 is characteristic of AlO 4 polyhedron, and one at 620630 cm ¹1 is characteristic of AlO 6 polyhedron.…”

Section: Ftir Analysismentioning

confidence: 98%

Preparation and characterization of monolithic Al2O3–SiO2 aerogel

Chen

Sui²,

Zhou³

et al. 2016

J. Ceram. Soc. Japan

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Al 2 O 3 SiO 2 aerogel was prepared through mixed solgel process and ethanol supercritical drying technology using aluminum chloride hexahydrate (AlCl 3 ·6H 2 O) and tetraethoxysilane (TEOS) as precursors. Under the condition of the propylene oxide used as gelation initiators, during the process, a kind of Al 2 O 3 SiO 2 aerogel with porous and large specific surface area were achieved in our experiments. Structures and properties of Al 2 O 3 SiO 2 aerogel are investigated by means of X-ray Diffraction, Nitrogen adsorption/desorption analysis, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscope, and Thermogravimetry-Differential Thermal analysis. The results showed that the Al 2 O 3 SiO 2 aerogel with the mole ratio of Al/Si = 3/1 possessed better heat-insulation performance and high-temperature stability. And it possessed a porous network structure made up of leaf shape particles. At the same time, Al 2 O 3 SiO 2 aerogel showed a low density of 0.071 g/cm 3 at room temperature, specific surface areas of 708 m 2 /g at 600°C, as well as 255 m 2 /g at 1200°C. The Al 2 O 3 SiO 2 aerogel is the polycrystalline boehmite (£-AlOOH) phase at room temperature. As the temperature growing, it transferred to £-Al 2 O 3 at 600°C, and mullite phase at 1200°C.

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Raman and infrared spectra on silica gel evolving toward glass

Cited by 608 publications

References 35 publications

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Pore ordering in mesoporous matrices induced by different directing agents

Preparation and characterization of monolithic Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> aerogel

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Raman and infrared spectra on silica gel evolving toward glass

Cited by 608 publications

References 35 publications

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO2–HfO2–SiO2 Ternary Oxide System

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO2–HfO2–SiO2 Ternary Oxide System

Pore ordering in mesoporous matrices induced by different directing agents

Preparation and characterization of monolithic Al<sub>2</sub>O<sub>3</sub>&ndash;SiO<sub>2</sub> aerogel

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Product

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Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO₂–HfO₂–SiO₂ Ternary Oxide System

Preparation and characterization of monolithic Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> aerogel