Raman and FTIR studies of some sol-gel based glasses in the ZnO-TiO 2-SiO2 system (original) (raw)
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Raman and ESR study of sol–gel materials from ZnO–TiO 2–B 2O 3 system
Journal of Non-crystalline Solids, 2009
The paper studies the materials from ZnO–TiO2–B2O3 ternary system, obtained by sol–gel method 1 and 2, starting from organic and inorganic precursors. The obtained samples are investigated by FTIR and Raman spectroscopy, which provide structural information, at molecular level. FTIR absorption maxima are identified and discussed according to literature data. Raman spectra are acquired by a Raman Jasco NRS-3100 spectrometer, at 532 nm wavelength and put in evidence characteristic vibration modes for all three oxide components. ESR spectra were plotted with the aid of a JES-FA 100-JEOL Japan spectrometer and titanium surrounding is investigated.
Spectrochimica Acta Part A: Molecular Spectroscopy, 1991
Infrared reflectance and Fourier transform Raman spectroscopy have been used to study silica and silicaltitania monoliths produced by the sol-gel route which had been subjected to a series of heat treatments. With increasing thermal treatment temperature, the gel-glass matrix is strengthed by bond shortening and a reduction in mean S-0-G bond angle and angular distribution for this feature. Results obtained at a range of temperatures were in good agreement to those obtained for vitreous silica. The incorporation of low levels (3% by weight) of titanium led to more disordered glasses which eontain titaniumin tetrahedral sites only. Evidence was obtained for the formation of Si-0-Ti bonds, principally during the latter stages of densification at temperatures between 615 and 1008'C.
Revue Roumaine De Chimie, 2006
The ternary zinc oxide-vanadium oxide-boron oxide system was studied in order to establish the compositional domain where glasses can be easily obtained by sol-gel method. The pH and temperature for optimal gelation is indicated. From infrared together with Fourier transformed infrared spectra it was concluded that, for some compositional domains, the boron oxide forms a mixed network together with the vanadium oxide. The thermogravimetric and differential thermal analysis revealed the temperatures for the vitreous transition and some crystalline transformation, and also the melting temperatures. The dielectric permitivity and dielectric loss were measured, and the dielectric loss factor calculated. The variation of dielectric properties to the electric field frequency and to composition is discussed. The variation curves of dielectric permitivity for 1 and 30 MHz were theoretically calculated and compared with the experimental ones, with good agreement.
Optical Materials, 2012
Glasses in ZnO-SiO 2 -B 2 O 3 ternary system with different ZnO/B 2 O 3 ratios were studied as scintillating materials. Differential thermal analysis and X-ray diffraction patterns showed that nucleation of willemite and zinc oxide was considerably facilitated with increasing the ZnO/B 2 O 3 ratio. Photoluminescence spectra showed a reduction in intensity over the UV region upon this increment prior to the formation of crystalline phases. Optical basicity as a measure of nonbridging oxygens (NBOs) is elaborated in this study as a major cause of this effect. However, near band edge emission (NBE) after crystallization implied an increase in intensity upon the increment of the ZnO/B 2 O 3 ratio which proved the key role of willemite and zinc oxide as UV emission centers.
Photoluminescent properties and Raman spectra of ZnO-based scintillating glasses
Journal of Non-crystalline Solids, 2008
Glasses in SiO 2 -ZnO-BaO system with the different ZnO/BaO ratio were studied. In some cases, BaF 2 was introduced to substitute for BaO on the equal base. Photoluminescent spectra showed that ZnO in glass matrices behaved somewhat differently from ZnO crystals. Especially, the introduction of fluorine ions led to dramatic shift of UV emission band of glasses closer to that of ZnO crystals. Raman spectral analysis provided consistent results. In particular, Raman bands in the high frequency region are sensitive to effects of different ZnO/BaO or BaF 2 /BaO ratio on structure of glasses.
Vibrational Spectroscopy, 2008
In this work we report on a vibrational spectroscopic study on the structural aspects of the binary xCaOÁ(100 À x)SiO 2 , xMgOÁ(100 À x)SiO 2 and ternary xCaOÁyMgO (100 À x À y)SiO 2 systems for various x values up to 50%. Raman and IR spectroscopies have revealed the degradation of the silica network with the addition of the oxide modifiers. The main differences in the spectra of the alkaline earth modified sol-gel glasses are located in the region 900-1200 cm À1 where vibrations of SiO 4 tetrahedra with a variable number of non-bridging oxygen atoms are located. A comparison between the structural modifications of bulk (melt-quenched) and porous glasses is also advanced revealing particular differences in the network modification of the two types of glasses. CaO is more drastic than MgO in depolymerizing silica's network and both of them cause more significant structure modifications in the sol-gel glasses. The depolymerization structural units offer the appropriate sites in the glass network that are responsible for the facilitation of Ca/Mg dissolution, which is an important step for bioactivity. Furthermore, to support the conclusions drawn from the experimental data, preliminary molecular structure simulations using semiempirical molecular orbital theory are also presented. #
Spectroscopic Studies of Silica/Titania Gel Glasses
Eurogel '91, 1992
Near and Mid infrared spectroscopy and FT-Raman spectroscopy have been used to study silica/ titania monoliths produced by the sol-gel route which have been subjected to selected heat treatments. Increasing thermal treatment temperature leads to a general strengthening of the gelglass matrix although the incorporation of low levels (3% by weight) of titanium into tetrahedral sites only, led to more disordered glasses than for silica alone. Evidence has been obtained for the formation of Si-O-Ti bonds principally during the later stages of densification at temperatures between 615 and 1000"C. The addition of titanium also leads to a reduction in surface 'free' silanol levels together with an increase in hydrogen bonded silanol levels and increasing amounts of water associated with the glass. The implication is that the incorporation of titanium onto the surface oi the gel matrix leads to tighter binding of water molecules to silanol groups.
Synthesis and Optical Properties of ZnO-TeO2 Glass System
American Journal of Applied Sciences, 2009
Problem statement: Systematic series of ZnO-TeO 2 glasses with mole fraction of 0.10-0.40 ZnO content with an interval of 0.05 were studied to obtain their physical and optical properties. Approach: All the glass samples were synthesized by rapid melting quenching method under controlled conditions, while their refractive indices (n) were measured by the EL X-02C high precision ellipsometer. The room temperature absorption of all glass samples were determined using Camspec M350 double beam UV-visible spectrophotometer. The infrared (IR) spectra of each glass samples were recorded with Thermo Nicolet Fourier Transform-Infrared (FT-IR) spectrophotometer. Their physical properties were measured and the amorphous nature was confirmed by the x-ray diffraction technique. Results: The increase of refractive index of the TeO 2 -ZnO glasses with the addition of ZnO was best explained in terms of either electron density or polarizability of the ions. The absorption edge shift to higher energy (shorter wavelength) with increasing ZnO content was observed in this glass. The optical band gap (E opt ) of zinc tellurite glass decreases with increasing of ZnO content probably due to the increment of Non-Bridging Oxygen (NBO) ion contents which eventually shifted the band edge to lower energies. Conclusion/Recommendation: The physical and optical properties of zinc tellurite glasses were found generally affected by the changes in the glass composition. FTIR spectra of zinc tellurite glass revealed broad, weak and strong absorption bands in the investigated range of wave numbers from 4000-400 cm −1 which associated with their corresponding bond modes of vibration and the glass structure. The addition of ZnO into TeO 2 glass network shifted the major band from 626 cm −1 (for pure TeO 2 glass) to the band at around 669 cm −1 .
Formation of ZnO in or on glasses by using the Sol-Gel and chemical bath deposition techniques
… on Circuits and …, 2010
In the first part of this work was produced Zinc Oxide (ZnO) into a glass matrix by using the Sol-Gel Technique at room temperature, these materials were prepared using tetraethyl orthosilicate (TEOS) as precursor, the Zn ions were added before the jellification step trough an aqueous solution of zinc acetate. These glasses were characterized by X-ray diffraction, optic absorption, FT-IR and Raman spectroscopy. The X-ray patterns showed amorphousness. The optical absorption shows a shoulder in the UV range corresponding whit ZnO confined to the vitreous matrix. The spectra by FT-IR show characteristic vibrations of Si-O-Si with interaction Zn +2 . Raman scattering let us to identify and precise the formation of the ZnO. In the second part of this work was immersed glass substrates into an aqueous chemical bath with external controlled temperature, the chemical solutions contained in the bath were a Zn Ions source (ZnSO 4 ) 0.1 M, a pH 10 Buffer solution (NH 4 Cl/NH 4 OH), Ethanolamine to complex the Zn ions, and pure water, resulting ZnO films hexagonally structured with energy band gap of 3.3 eV, growing 1000 nm during 25 minutes followed of 60 minutes to 75°C and 85°C in the same chemical reaction.
Crystallization of gel-derived and quenched glasses in the ternary oxide Al2O3–ZrO2–SiO2 system
Journal of Non-Crystalline Solids, 2002
We studied glass formation in the SiO 2-rich region of the ternary oxide system Al 2 O 3-ZrO 2-SiO 2. Gels with the composition 5-5-90 mol% have been synthesized by the sol-gel method in acid media and then treated up to 1650°C and kept for 2 and 10 h. A glass with the same composition has been obtained by quenching in water from the melt. The structural evolution of gels annealed at different temperatures up to 1650°C was followed by thermal analysis, X-ray diffraction, specific surface area, density measurements and IR spectroscopy. The materials consisted mainly of amorphous phase up to 1200°C, at which partial crystallization of cristobalite was observed. The presence of Zr and Al in the silica network at high temperatures was investigated by IR spectroscopy. The crystallization of gels at high temperatures and the crystalline phases formed are related to the preparation conditions and the thermal treatment. For samples from quenched melts zircon was the only crystalline phase detected, while in the case of the samples slowly cooled down from 1650°C, zircon, silica, zirconia and alumina or mullite were observed depending on the treatment time.