Nanocrystalline SnO2 Particles and Twofold-coordinated Sn Defect Centers in Sol-gel-derived SnO2–SiO2 Glasses

2002 ◽  
Vol 17 (6) ◽  
pp. 1305-1311 ◽  
Author(s):  
Tomokatsu Hayakawa ◽  
Takehiro Enomoto ◽  
Masayuki Nogami
Keyword(s):  
Quantum Confinement ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Stannic Oxide ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Absorption Edge Shift ◽  
Electron Hole Pair

Semiconductive nanocrystals of stannic oxide (SnO2) were precipitated in silica (SiO2) glasses synthesized via a sol-gel route. Kayanuma's equation, which describes the quantum confinement of an electron–hole pair in a semiconductive particle, well explained the absorption-edge shift due to the SnO2 nanocrystals in the optical absorption spectra. The adequate anneal of the SnO2–SiO2 glass ceramics in H2 gas led to the decomposition of the SnO2 nanocrystals and concurrently the production of twofold-coordinated tin atoms (Sn20 ) that provided a violet photoluminescence. The thermal behavior was studied with the x-ray diffraction measurement and photoluminescence and photoluminescence excitation spectroscopy.

scholarly journals Physical analysis of TiO2 and bentonite nanocomposite as adsorbent materials

2021 ◽  
Vol 60 (1) ◽  
pp. 912-920
Author(s):  
Nurdin Bukit ◽  
Eva Marlina Ginting ◽  
Erna Frida ◽  
Bunga Fisikanta Bukit
Keyword(s):  
Sol Gel ◽  
Synthesis Method ◽  
Infrared Analysis ◽  
Physical Analysis ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Sol Gel Process ◽  
Electron Hole Pair ◽  
Adsorbent Materials

Abstract The research analyzed the physical properties of TiO2 and bentonite nanocomposite as adsorbent materials. The TiO2 synthesis method was carried out through a sol–gel process. Meanwhile the synthesis of bentonite was carried out by the ball mill, coprecipitation and addition of cetyltrimethylammonium bromide (CTAB) surfactant. X-ray diffraction nanocomposite characterization showed that the particle size was 17.13 nm. Fourier transform infrared analysis showed the required absorption peak in photocatalysis because the OH group can react with holes and prevent electron–hole pair recombination. The morphology of the nanocomposite showed the occurrence of TiO2 pillarization in bentonite. The results of the X-ray fluorescence nanocomposite showed that the content of TiO2 and SiO2 was 65.22 and 17.4%, respectively.

Few-Layered MoS2 Nanostructures for Highly Efficient Visible Light Photocatalysis

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650114 ◽  
Author(s):  
Dan Li ◽  
Jianwei Li ◽  
Caiqin Han ◽  
Xinsheng Zhao ◽  
Haipeng Chu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Electrochemical Impedance Spectra ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Hole Pair

Few-layered MoS2 nanostructures were successfully synthesized by a simple hydrothermal method without the addition of any catalysts or surfactants. Their morphology, structure and photocatalytic activity were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electrochemical impedance spectra and UV-Vis absorption spectroscopy, respectively. These results show that the MoS2 nanostructures synthesized at 180[Formula: see text]C exhibit an optimal visible light photocatalytic activity (99%) in the degradation of Rhodamine B owing to the relatively easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination.

Effects of Glass Elements on the Structural Evolution ofin situGrown Ferroelectric Perovskite Crystals in Sol-gel Derived Glass-ceramics

1997 ◽  
Vol 12 (4) ◽  
pp. 1131-1140 ◽  
Author(s):  
Kui Yao ◽  
Weiguang Zhu ◽  
Liangying Zhang ◽  
Xi Yao
Keyword(s):  
Crystallization Process ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Structural Evolution ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
Process Change ◽  
X Ray ◽  
Ferroelectric Perovskite

Several ABO3perovskite ferroelectric crystals, PbTiO3, Pb(Zr, Ti)O3, and BaTiO3have beenin situgrown from amorphous gels with glass elements, and the structural evolution has been systematically investigated using x-ray diffraction (XRD), infrared spectra (IR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and dielectric measurements. It is found that in the Si-contained glass-ceramic systems, Si and B glass elements are incorporated into the crystalline structures, resulting in the variation of the crystallization process, change of lattice constant, and dielectric properties. Some metastable phases expressed by a general formula AxByGzOw(A = Pb and Ba; B = Zr and Ti; G for glass elements, especially for Si) have been observed and discussed.

Gel-derived amorphous cesium-aluminosilicate powders useful for formation of pollucite glass-ceramics

1991 ◽  
Vol 6 (2) ◽  
pp. 217-219 ◽  
Author(s):  
Mari A. Hogan ◽  
Subhash H. Risbud
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Amorphous Powder ◽  
Glass Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Powders ◽  
Gel Processing ◽  
Scanning Electron

Amorphous powders in the Cs2O–Al2O3−SiO2 system were prepared by sol-gel processing. Gels made from TEOS, Al-chelate, and Cs-acetate were dried and calcined to obtain molecularly mixed powders of analyzed compositions in the range useful for conversion to pollucite (CsAlSi2O6) glass-ceramics. X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), and scanning electron microscopy (SEM) were used to characterize the powders. A typical amorphous powder of analyzed chemical composition (in wt.%) = 28.05Cs2O, 37.77SiO2, and 37.96Al2O3 was found to have a glass transition temperature of 945 °C and a glass crystallization temperature of 1026 °C. Preliminary experimental results of densification and crystallization of the amorphous powders show pollucite/mullite phases to be present.

MgO-Al2O3-SiO2 Glass-Ceramic Prepared by Sol-Gel Method

2010 ◽  
Vol 92 ◽  
pp. 131-137 ◽  
Author(s):  
Qiu Hua Yuan ◽  
Pei Xin Zhang ◽  
Li Gao ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Crystallization Behavior ◽  
Glass Powder ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Green Body ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Sio2 Glass ◽  
X Ray

The crystallization behavior of MgO-Al2O3-SiO2 glass-ceramics by sol-gel technology was investigated by using x-ray diffraction (XRD), differential thermal analysis (DTA), Scanning electron microscopy (SEM). The results showed that: (1)α-cordierite phase was precipitated when the green body was calcined at 1050°C, and α-cordierite of high purity and stability could be formed at 1100°C; (2) Adding an appropriate amount of low melting point glass powder into the green body may provide liquid-phase environment during the sintering process, which will help enhance the tightness density of glass-ceramic, and thus improve its flexural strength.

Characterization of Fe2O3-CaO-SiO2 Glass Ceramics Prepared by Sol-Gel

2014 ◽  
Vol 624 ◽  
pp. 114-118 ◽  
Author(s):  
Yao Yao Wang ◽  
Bin Li ◽  
Yong Ya Wang
Keyword(s):  
Sol Gel ◽  
Glass Ceramics ◽  
Optimum Process ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
Crystallization Activation Energy ◽  
Treatment Technology ◽  
X Ray ◽  
Heat Treatment Technology

Ferromagnetic glass ceramics with magnetism and biological activity could be used for magnetic induction hyperthermia. In this study Fe2O3-CaO-SiO2glass-ceramics were prepared by sol-gel method. The sample was characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). The results showed that the major phases of the sample are wollastonite and magnetite and the crystallization activation energy of sample is 189.3KJ/mol, which would provide a theoretical basis for the establishment of the optimum process conditions of heat treatment technology.

Synthesis and Processing of the Sol-Gel Derived β-Quartz Lithium Aluminum Silicates

1986 ◽  
Vol 73 ◽  
Author(s):  
J. Covino ◽  
F. G. A. De Laat ◽  
R. A. Welsbie
Keyword(s):  
Particle Size ◽  
Glass Ceramic ◽  
Diffuse Reflectance ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Aluminum Silicate ◽  
Lithium Aluminum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis And Processing

ABSTRACTLithium Aluminum Silicate (LAS) glass-ceramic compositions with and without phosphorous have been synthesized by Sol-Gel techniques. Resulting LAStype powders are herein designated as NZ and NZP. X-Ray analysis, thermogravimetric analysis (TGA), particle size measurements, and thermal dilatometric shrinkage measurements have been performed on these samples. The NZ and NZP powders in calcined form, as well as commercially-available LAS glass-ceramic produce x-ray diffraction pattern very similar to the pattern of Virgilite LixAlxSi3−xO6 (x=0.5–1.0). There is little difference between powders with and without phosphorous in the diffuse reflectance spectra (DRS). Preliminary results show that the material can be easily processed into glass ceramics.

Preparation, Dielectric and Magnetic Properties of Barium-Ferrite-Containing Microcrystalline Glass Ceramic by Citrate Sol-Gel Process

2007 ◽  
Vol 280-283 ◽  
pp. 457-460 ◽  
Author(s):  
Hai Jun Zhang ◽  
Xiao Lin Jia ◽  
Xi Yao ◽  
Liang Ying Zhang
Keyword(s):  
Dielectric Constant ◽  
Barium Ferrite ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Complex Dielectric Constant ◽  
Complex Permeability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Process ◽  
Scanning Electron

Four kinds of barium-ferrite-containing microcrystalline glass ceramics, such as BaFe12O19/SiO2, BaFe12O19/SiO2-B2O3, BaFe12O19/SiO2-B2O3-K2O and BaFe12O19/SiO2-Al2O3-K2O were prepared by citrate sol-gel process, in which inceptive formation temperatures varied from 850°C to 1100°C. The complex dielectric constant and complex permeability of those glass ceramics were measured at 0.1-5.0GHz, and the frequency dependence of complex dielectric constant and permeability was studied. The microcrystalline glass ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM).

scholarly journals Synthesis and Characterization of Ag-Modified V2O5Photocatalytic Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Dora Alicia Solis-Casados ◽  
Luis Escobar-Alarcon ◽  
Antonia Infantes-Molina ◽  
Tatyana Klimova ◽  
Lizbeth Serrato-Garcia ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Silver Content ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Simulated Solar Light ◽  
Malachite Green Dye ◽  
Electron Hole Pair ◽  
O Phase

V2O5powders modified with different theoretical silver contents (1, 5, 10, 15, and 20 wt% as Ag2O) were obtained with acicular morphologies observed by scanning electron microscopy (SEM). Shcherbinaite crystalline phase is transformed into the Ag0.33V2O5crystalline one with the incorporation and increase in silver content as was suggested by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With further increase in silver contents the Ag2O phase appears. Catalysts were active in photocatalytic degradation of malachite green dye under simulated solar light, which is one of the most remarkable facts of this work. It was found that V2O5-20Ag was the most active catalytic formulation and its activity was attributed to the mixture of coupled semiconductors that promotes the slight decrease in the rate of the electron-hole pair recombination.

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