Raman spectra of gel-prepared titania-silica glasses

Knight, Diane S.; Pantano, Carlo G.; White, William Β.

doi:10.1016/0167-577x(89)90182-1

Cited by 33 publications

(19 citation statements)

References 18 publications

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“…The Raman spectrum also shows the characteristic Ti-O-Ti bands at 955 and 1100 cm -1 for the symmetric and the antisymmetric stretch, respectively (Fig. 2-top right) [71,72].…”

Section: Characterization Of Mtsmmentioning

confidence: 99%

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

et al. 2018

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An efficient approach to improve the catalytic activity of titanosilicates is introduced. The Doehlert matrix (DM) statistical model was utilized to probe the synthetic parameters of mesoporous titanosilicate microspheres (MTSM), in order to increase their catalytic activity with a minimal number of experiments. Synthesis optimization was carried out by varying two parameters simultaneously: homogenizing temperature and surfactant weight. Thirteen different MTSM samples were synthesized in two sequential 'matrices' according to Doehlert conditions and were used to catalyse the epoxidation of cyclohexene with tert-butyl hydroperoxide. The samples (and the corresponding synthesis conditions) with superior catalytic activity in terms of product yield and selectivity were identified. In addition, this approach revealed the limiting values of each synthesis parameter, beyond which the material becomes catalytically ineffective. This study demonstrates that the DM approach can be broadly used as a powerful and time-efficient tool for investigating the optimal synthesis conditions of heterogeneous catalysts. Abbreviation

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“…The Raman spectrum also shows the characteristic Ti-O-Ti bands at 955 and 1100 cm -1 for the symmetric and the antisymmetric stretch, respectively (Fig. 2-top right) [71,72].…”

Section: Characterization Of Mtsmmentioning

confidence: 99%

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

et al. 2018

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“…Due to the low MO content in the glasses, the addition of ZnO, GeO 2 , and TiO 2 should lead to the formation of ZnO 4 with Si‐O‐Zn bond formation with IR band at 940 cm −1 , GeO 4 units with Ge‐O‐Ge bonds with IR bands at 870 cm −1 and of TiO 4 units with Si‐O‐Ti bonds with IR absorption band at ~900 cm −1 . Ga is expected to enter into the network as GaO 4 tetrahedral with IR band in the region ~613–620 cm −1 (not seen here) and Al as AlO 4 units with an IR band at 900 cm −1 .…”

Section: Resultsmentioning

confidence: 84%

Ternary borosilicates as potential cladding glasses for semiconductor core optical fibers

Dmitrieva

Lopez-Iscoa

Milanese

et al. 2018

Int J of Appl Glass Sci

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Our study advances the development of new ternary silicate glasses for use as a designed cladding for semiconductor core optical fibers using molten core draw process. In order to fabricate high-quality hybrid fibers (homogeneous core shape, low amount of bubbles, low internal stress, no cracking), oxide glasses are the best choice as cladding materials. These glasses should be engineered with tailored thermal properties (coefficient of thermal expansion (CTE) and drawing temperature) so they match those of the semiconductor. Glasses in the system) with x = 0 and 10 and MO and in the system 50SiO 2 -10Na 2 O-(40 − y)B 2 O 3 -yTiO 2 with y = 0, 1.25, 2.5, and 5 were investigated. Their thermal properties were measured and discussed with regard to the glass structure analyzed using FTIR spectroscopy. Due to their rigid network, which leads to beneficial thermal properties including low CTE (~5 ppm K −1 ), the Ge-containing glass with x = 10 is a promising cladding candidate when preparing a Ge core fiber and the Ga or Zn-containing glasses when preparing an InAs core.

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“…Near 120 meV, notably, there is a small intensity that can be seen in all the binary-mix samples, but is absent in FS sample. Earlier Raman scattering studies of titania silicate glass has attributed it to the T i 4+ related vibration modes 22,23 . Here, the peak is observed in both T iO 2 and K 2 O mixed silicate glass, indicating that this peak is possibly related to the Si-O-X or Si-O-R bond vibrations in a mixed silicate system, as similarly speculated in an earlier study on sodium titania silicate system 24 .…”

Section: Resultsmentioning

confidence: 99%

Low-temperature vibrational dynamics of fused silica and binary silicate glasses

et al. 2018

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Inelastic neutron scattering was used to study the vibrational dynamics of fused silica and its mixed binary glasses that were doped with either T iO2 or K2O. The energy transfer were measured from zero to 180 meV where the so-called Boson peaks (BP) at low energy and molecular vibrations at high energy are included. Although most of the vibrational spectra at the high energy resemble those reported in earlier literatures, a defect mode like peak is observed for the doped binary systems near 120 meV. At very low temperature, the BP intensity increases rapidly with temperature and then, at higher temperature, the peak intensity decreases. As a result, a maximum is observed in the temperature dependence of the BP intensity. This maximum was shown in all four samples but the pure SiO2 sample shows the highest intensity peak and the lowest temperature for peak position. Broadband energy spectra reveal a shift of intensity from BP to the more localized modes at higher energy. Temperature evolution of BP and its relationship with heat conduction and thermal expansion are discussed.

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Raman spectra of gel-prepared titania-silica glasses

Cited by 33 publications

References 18 publications

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

Ternary borosilicates as potential cladding glasses for semiconductor core optical fibers

Low-temperature vibrational dynamics of fused silica and binary silicate glasses

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