Formation of silicate structures in Cu-containing silica xerogels

2000 ◽  
Vol 15 (12) ◽  
pp. 2875-2880 ◽  
Author(s):  
F. Ruiz ◽  
J. R. Martínez ◽  
J. González-Hernández
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Infrared Absorption ◽  
Sol Gel ◽  
Heat Treatments ◽  
Thermal Treatments ◽  
Chemical Formula ◽  
Silica Xerogels ◽  
Weight Composition ◽  
Oxide Particles

Using infrared absorption and Raman spectroscopy, the structure of SiO2 sol-gel samples containing copper were analyzed as a function of air heat treatments. The weight composition of the samples was 70(SiO2)–30(CuO) and the thermal treatments were carried out in air at various temperatures in the range of 100–600 °C. It was found that the Cu might be incorporated into the SiO2 matrix at least in two ways: forming oxide particles and forming metasilicatelike structures. The copper metasilicate found had the chemical formula, Cu6 [Si6O18] · 6H2O, which is known as dioptase with a thermal stability at temperatures up to 600 °C.

Structural Changes of TiO2 as a Result of Irradiation by E-Beam and X-Rays

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Perica Paunović ◽  
Anita Grozdanov ◽  
Petre Makreski ◽  
Gennaro Gentile
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Photocatalytic Activity ◽  
Thermal Treatment ◽  
Structural Changes ◽  
Sol Gel ◽  
X Rays ◽  
Beam Irradiation ◽  
X Ray ◽  
The Subject

Abstract The subject of this research was to monitor and evaluate the effect of X-rays and e-beam irradiation on the structure of nanoscaled TiO2 and its properties. The samples of nanoscaled TiO2 were synthesized using the sol–gel method and subsequently exposed to thermal treatment to obtain the anatase crystalline structure. X-ray powder diffraction (XRPD) and Raman spectroscopy revealed the following changes in the structure as a result of the e-beam and X-ray irradiation: a decrease in the size of the crystallite of TiO2, an increase of the distance between the crystalline planes and the lattice parameters as well as the achievement of a certain degree of amorphization. As a consequence of the structural changes, thermal stability decreased. Also, a shift of the light absorption toward the visible end of the spectrum was detected and the energy of the band gap was reduced, indicating a better photocatalytic activity, i.e., the photocatalytic action can be shifted to the region of the visible light.

scholarly journals Surface Enhanced Infrared Absorption Studies of SiO2–TiO2–Ag Nanofibers: Effect of Silver Electrodeposition Time on the Amplification of Signals

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 563
Author(s):  
Blanca Selenis Cabello-Ribota ◽  
Rurik Farías ◽  
Simón Yobanny Reyes-López
Keyword(s):  
Raman Spectroscopy ◽  
Infrared Spectroscopy ◽  
New Media ◽  
Infrared Absorption ◽  
Indium Tin Oxide ◽  
Amplification Factor ◽  
Sol Gel ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Surface Enhanced

Surface Enhanced on Infrared Absorption (SEIRAS) and Raman Spectroscopy (SERS) are nondestructive analytic techniques used to detect low concentrations and recognize the fingerprints of molecules. The recognition of the absorption from samples by conventional infrared spectroscopy (IR) via Attenuated Total Reflection (ATR) is difficult for molecules with a low signal strength. However, developed structures with SERS and SEIRAS effect present problems such as high cost, low stability, and low compatibility. Research into new media to obtain greater amplification is largely based on the creation of nanoscale structures with symmetrical arrangements and reproducible distances, resulting in aggregates of nanoparticles that help generate hot spots which are active for amplification. The sol-gel and electrospinning method for the obtention of ceramics provides an alternative means by which to produce said substrates. Fibers of nanometric scale provide an increase of surface area which allows more contact to occur with analytes. Consequently, in this study, a silica-titania-silver nanostructured support that amplifies signal intensity for Raman and infrared spectroscopy was developed. The silica-titania support was developed by sol-gel and electrospinning techniques, and the as spun fibers were treated at 800 °C. Then, the ceramic fibrous membrane was placed on conductive indium tin oxide plastic to be doped with silver using an electroplating technique, varying the silver nitrate concentration (5, 10 and 20 mM), as well as electrodeposition times (1, 2, 5 and 10 min), with a constant voltage (1 V). Twelve different supports were obtained that showed amplification. The enhancement of infrared signals from pyridine and crystal violet molecules adsorbed on silica-titania-silver (SiO2–TiO2–Ag) nanofibers was studied in situ by Attenuated Total Reflection-Fourier Transformed Infrared Spectroscopy (ATR-FTIR). The highest amplification was obtained by the support doped at 10 min in a 10 mM concentration, with an amplification factor of 2.74 in the band localized at 3301 cm−1. In Raman spectroscopy, the highest amplification factor was 27.03, on the support doped for 5 min at a concentration of 5 mM.

scholarly journals Synthesis and photocatalytic properties of Sn–TiO2 nanomaterials

2020 ◽  
Vol 10 (01n02) ◽  
pp. 2060018
Author(s):  
E. M. Bayan ◽  
T. G. Lupeiko ◽  
L. E. Pustovaya ◽  
M. G. Volkova
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Sol Gel ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Light Activation ◽  
X Ray ◽  
Tio2 Nanomaterials ◽  
Visible Light Activation ◽  
Thermal Stability Of

Sn-doped TiO2 nanomaterials were synthesized by sol–gel method. It was shown the phase compositions and phase transitions change with the introduction of different tin amounts (0.5–20[Formula: see text]mol.%). X-ray powder diffraction was used to study the effect of different tin amounts on the anatase–rutile phase transition. It was found that the introduction of ions increases the thermal stability of anatase modifications. The material’s photocatalytic activity was studied in reaction with a model pollutant (methylene blue) photodegradation under UV and visible light activation. The best photocatalytic properties were shown for material, which contains 5[Formula: see text]mol.% of Sn.

Thermal stability and plasmonic photothermal conversion of surface-modified solar nanofluids: Comparing prolonged and cyclic thermal treatments

2021 ◽  
Vol 244 ◽  
pp. 114463
Author(s):  
Omar Z. Sharaf ◽  
Nahla Rizk ◽  
Catherine J. Munro ◽  
Chakra P. Joshi ◽  
Waqas Waheed ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Treatments ◽  
Photothermal Conversion ◽  
Surface Modified

Cobalt-Doped Silica Organic-Inorganic Materials by Sol-Gel Method: Preparation and Thermal Stability Calcined under N2 Atmosphere

2021 ◽  
Vol 219 (1) ◽  
pp. 247-259
Author(s):  
Jing Yang ◽  
Yuzhi Ai ◽  
Wangqing Fan ◽  
Ruihua Mu ◽  
Xi Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Sol Gel ◽  
Inorganic Materials ◽  
Gel Method ◽  
Sol Gel Method ◽  
N2 Atmosphere

Eu3+/Tb3+ Co-Doped Cerium Oxide Transparent Nanocomposite for Color-Tunable Emission

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850119
Author(s):  
Xiaoyan Li ◽  
Yunlong Yu ◽  
Xiangfeng Guan ◽  
Peihui Luo ◽  
Linqin Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Homogeneous Precipitation ◽  
Transmission Electron ◽  
Color Tunable ◽  
Co Doped ◽  
Tunable Emission

Eu[Formula: see text]/Tb[Formula: see text] co-doped nanocomposite containing CeO2 nanocrystals was successfully prepared by an in situ sol–gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of CeO2 nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of CeO2 content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

Preparation of ultrafine RuO2IrO2TiO2 oxide particles by a sol—gel process

1994 ◽  
Vol 39 (13) ◽  
pp. 1993-1997 ◽  
Author(s):  
Yoshio Takasu ◽  
Satoshi Onoue ◽  
Kohichi Kameyama ◽  
Yasushi Murakami ◽  
Kiyochika Yahikozawa
Keyword(s):  
Sol Gel ◽  
Sol Gel Process ◽  
Oxide Particles

Thermal stability of europium(III) chelate encapsulated by sol–gel glass

2009 ◽  
Vol 480 (2) ◽  
pp. 908-911 ◽  
Author(s):  
E. Kin ◽  
T. Fukuda ◽  
S. Yamauchi ◽  
Z. Honda ◽  
H. Ohara ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Sol Gel ◽  
Thermal Stability Of
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