The effect of TiO2addition on the preparation and phase transformation for precursor β-spodumene powders

1994 ◽  
Vol 9 (9) ◽  
pp. 2290-2297 ◽  
Author(s):  
Moo-Chin Wang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Sol Gel ◽  
Peak Position ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Amorphous Powders ◽  
Lower Temperature ◽  
Dta Curves ◽  
A Minor

Fine β-spodumene-type amorphous powders were obtained through sol-gel techniques using Si(OC2H5)4, Al (OC2H5)3, LiOCH3, and Ti(OC2H5)4as the starting metal alkoxides. Differential thermal analysis (DTA), x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron diffraction (ED) analysis were utilized to study the phase transformation behavior of the LAST gels. The viscosity of the LAST solution increased abruptly at longer time when the TiO2content was increased. As the TiO2content was increased, the peak position of β-spodumene phase formation in DTA curves was shifted to a lower temperature. For calcination of LAST gels at 800°-1200 °C, the crystallized phases are composed of the major phase of β-spodumene and a minor phase of rutile (TiO2). Unlike earlier studies, heating the dried LAST gels from 800 °C to 1200 °C did not show β-eucryptite, nor found γ-spodumene.

Phase transformation and characterization of TiO2 and ZrO2 addition in the Li2O–Al2O3-SiO2 gels

1996 ◽  
Vol 11 (10) ◽  
pp. 2611-2615 ◽  
Author(s):  
Ming-Hong Lin ◽  
Moo-Chin Wang
Keyword(s):  
Phase Transformation ◽  
Sol Gel ◽  
Peak Position ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
Ceramic Powders ◽  
Higher Temperature ◽  
Gel Technique ◽  
Dta Curves

Glass-ceramic powders with a composition of Li2O · Al2O3 · 4SiO2 (LAS) have been synthesized by the sol-gel technique using LiOCH3, Al(OC2H5)3, Si(OC2H5)4, Ti(OC2H5)4, and Zr(OC2H5)4 as starting materials and the phase transformation behavior during calcination has been investigated. Differential thermal analysis (DTA), x-ray diffraction (XRD), and scanning electron microscopy (SEM) were utilized to determine the thermal behavior of the gels. Considering the LAS gels with 6.0 wt. % TiO2 and various wt. % ZrO2 content, and peak position of the β-spodumene phase formation in DTA curves was shifted to a higher temperature when the ZrO2 content was increased. The activation energy of β-spodumene crystallization was 283.8 kcal/mol for LAS gels with 6.0 wt. % TiO2 and 2.0 wt. % ZrO2. Unlike foregoing studies for LAS gels, during calcination of the dried LASTZ gels from 800 °C to 1200 °C neither β-eucryptite nor γ-spodumene was noted to be present. The crystallized phases comprised of β-spodumenes as the major phase and rutile (TiO2) together with zirconia (ZrO2) are precipitated as minor phases.

Effect of TiO2 addition on the preparation of β-spodumene powders by sol-gel process

1999 ◽  
Vol 14 (1) ◽  
pp. 196-203 ◽  
Author(s):  
Moo-Chin Wang ◽  
Ming-Hong Lin ◽  
Hok-Shing Liu
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Sol Gel ◽  
Gelation Time ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Fine Glass ◽  
A Minor

This study has shown the possibility of achieving two primary considerations for the advanced fabrication of spodumene with a composition of Li2O · Al2O3 · 4SiO2 · nTiO2 (LAST) glass-ceramics by a sol-gel process, namely, an enormous reduction of sintering temperature from 1600 to 1200 °C together with the appearance of simple phases of β-spodumene/rutile as opposed to products via the conventional melting-crystallization process. Fine glass-ceramic powders with a composition of Li2O · Al2O3 · 4SiO2 (LAS) have been synthesized by the sol-gel process using Si(OC2H5)4, Al(OC2H5)3, LiOCH3, and Ti(OC2H5)4 as the starting materials. The process included well-controlled hydrolysis polycondensation of the raw alkoxides. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron diffraction (ED) analysis were utilized to study the effect of TiO2 addition on the preparation of β-spodumene powders by the sol-gel process. The gelation time of the LAST solution increases as the TiO2 content increases. For the low (<3) or high (>11) pH value, the gelation time was shortened. At pH = 5, regardless of the TiO2 content, the gel has the longest time of gelation. When the dried gels of the LAST system are heated from 800 to 1200 °C, the crystallized samples are composed of the major phase of β-spodumene and a minor phase of rutile (TiO2).

Synthesis of LaMnO3–Diamond Composites and Their Photocatalytic Activity in the Degradation of Weak Acid Red C-3GN

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850121 ◽  
Author(s):  
Hao Huang ◽  
Benqian Lu ◽  
Yuanyuan Liu ◽  
Xeuqian Wang ◽  
Jie Hu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Active Sites ◽  
Sol Gel ◽  
Peak Position ◽  
Weak Acid ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Excellent Photocatalytic Activity ◽  
The Fourier Transform

In this study, a series of LaMnO3–diamond composites with varied LaMnO3 mass contents supported on micro-diamond have been synthesized using a sol–gel method. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and the Fourier transform infrared spectra (FTIR). Meanwhile, the photocatalytic performances were also tested by photoluminescence (PL) spectroscopy, ultraviolet–visible diffuse reflection spectra (UV-Vis DRS) and the degradation of weak acid red C-3GN (RC-3GN). Results show that the peak position of LaMnO3 is shifted to low angle after the introduction of diamond, and perovskite particles uniformly distributed on the surface of diamond, forming a network structure, which can increase the active sites and the absorption of dye molecules. When the mass ratio of LaMnO3 and diamond is 1:2 (LMO–Dia-2), the composite shows the most excellent photocatalytic activity. This result offers a sample route to enlarge the range of the application of micro-diamond and provide a new carrier for perovskite photocatalysts.

The effect of TiO2 addition on the thermal behavior of sol-gel derived β-spodumene powders

1999 ◽  
Vol 14 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Moo-Chin Wang
Keyword(s):  
Phase Transformation ◽  
Sol Gel ◽  
Transformation Process ◽  
X Ray Diffraction ◽  
Crystallization Sequence ◽  
X Ray ◽  
Transmission Electron ◽  
Tio2 Addition ◽  
A Minor ◽  
Increasing Temperature

The effect of TiO2 addition on the crystallization and phase transformation process in Li2O · Al2O3 · 4SiO2 gels with various TiO2 contents was investigated using differential thermal analysis, x-ray diffraction, and transmission electron microscopy. The activation energy increased from 98.2 to 184.6 kcal/mol as the TiO2 content rose from 2.0 to 8.0 wt. %. The crystallization sequence and phase transformation were similar in LAS gels with various wt.% of TiO2 additions, except in the case of a 2.0 wt.% TiO2 content. During calcination from 800 to 1200 °C, crystallization of the β-spodumene phase progressed with increasing temperature, and a minor crystalline phase, rutile, also appeared.

Synthesis, Characterization, and Microwave Absorption Properties of SrFe12O19 Ferrites and FeNi3 Nanoplatelets Composites

2010 ◽  
Vol 148-149 ◽  
pp. 893-896 ◽  
Author(s):  
Ze Yang Zhang ◽  
Xiang Xuan Liu ◽  
You Peng Wu
Keyword(s):  
Electron Microscopy ◽  
Microwave Absorption ◽  
Composite Coatings ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Filling Fraction ◽  
Microwave Absorption Properties ◽  
Phase Reduction ◽  
Transmission Electron

M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were successfully prepared by the sol-gel method and solution phase reduction method, respectively. The crystalline and morphology of particles were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The composite coatings with SrFe12O19 ferrites and FeNi3 nanoplatelets in polyvinylchloride matrix were prepared. The microwave absorption properties of these coatings were investigated in 2-18GHz frequency range. The results showed that the M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were obtained and they presented irregular sheet shapes. With the increase of the coating thickness, the absorbing peak value moves to the lower frequency. The absorbing peak values of the wave increase along with the increasing of the content of FeNi3 nanoplatelets filling fraction. When 40% SrFe12O19 ferrites is doped with 20% mass fraction FeNi3 nanoplatelets to prepare composite with 1.5mm thickness, the maximum reflection loss is -24.8 dB at 7.9GHz and the -10 dB bandwidth reaches 3.2GHz.

scholarly journals Magnetic PbFe12O19-TiO2 nanocomposites and their photocatalytic performance in the removal of toxic pollutants

2018 ◽  
Vol 41 (3-4) ◽  
pp. 53-62 ◽  
Author(s):  
Behnaz Lahijani ◽  
Kambiz Hedayati ◽  
Mojtaba Goodarzi
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Sol Gel ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Photocatalytic Effect ◽  
Transmission Electron ◽  
Ultraviolet Light Irradiation

Abstract In this work, the PbFe12O19 nanoparticles were prepared by the simple and optimized precipitation method with different organic surfactants and capping agents. In the next step, the TiO2 nanoparticles were synthesized using the sol-gel method. At the final step, the PbFe12O19-TiO2 nanocomposites were prepared via the sol-gel method. The effect of the precipitating agent on the morphology and particle size of the products was investigated. The prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The results obtained by the vibrating sample magnetometer show the magnetic properties of the ferrite nanostructures. The photocatalytic effect of the PbFe12O19-TiO2 nanocomposite on the elimination of the azo dyes (acid black, acid violet and acid blue) under ultraviolet light irradiation was evaluated. The results indicate that the prepared nanocomposites have acceptable magnetic and photocatalytic performance.

Sensing Properties of CNT hybrid MOS-based Sensors

2004 ◽  
Vol 828 ◽  
Author(s):  
Wei-Jen Liou ◽  
Tsung-Yeh Yang ◽  
Kuang-Nan Lin ◽  
Ching-Hong Yang ◽  
Hong-Ming Lin
Keyword(s):  
Electron Microscopy ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
Sol Gel ◽  
Gas Sensitivity ◽  
Sensing Properties ◽  
Operation Temperature ◽  
Transmission Electron ◽  
Lower Temperature ◽  
P Type

ABSTRACTThe carbon nanotubes provide large surface that can enhance the gas adsorption properties and increase the conductivity at a lower temperature for gas sensing. The gas sensing properties of the hybrid TiO2/CNTs material are examined in this study. The sol-gel technique is used to prepare a thin layer of nano-TiO2 coated on CNTs. The structure of TiO2/CNTs hybrid materials is identified by X-ray diffraction (XRD) and Raman spectrum. The granules and surface morphology are analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical properties of the hybrid TiO2/CNTs indicate that the operation temperature can be lowered to ambient temperature and this will enhance the gas sensitivity for detecting CO gas. The n-type or p-type behavior of hybrid TiO2/CNTs can be controlled by the coating thickness of hybrid TiO2. According to the image results, the mechanisms of the n-type and p-type behavior of hybrid TiO2/CNTs system are proposed.

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

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.

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