Preparation And Characterization Of Ultra-Small Sized Metal And Semiconductor Particles In Sol-Gel Materials

1994 ◽  
Vol 346 ◽  
Author(s):  
Kyung Moon Choi ◽  
Kenneth J. Shea
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Sol Gel ◽  
High Vacuum ◽  
Particle Sizes ◽  
Transition Metal Clusters ◽  
Surface Areas ◽  
Sol Gel Process ◽  
Bridged Silsesquioxanes

ABSTRACTPoly(l,4-phenylene)-bridged and poly(1,6-hexylene)-bridged silsesquioxanes (PPS and HPS) were prepared by the sol-gel process. The surface areas and pore diameters of these porous xerogels were obtained by BET and BJH methods, respectively. These porous materials were used as a confinement matrix for the growth of small-sized semiconductor and transition metal clusters. Quantum-sized CdS particles in PPS (approximately 58+12 Â) and HPS (91+16 Â) matrices were prepared by first soaking the xerogel in a CdCl2 solution. Following a washing with water, a Na2S solution was then added. EDAX and electron diffraction techniques were used to identify the CdS particles. The particle sizes of CdS in PPS and HPS were determined by both UV measurements and from TEM images. Small-sized Cr clusters were prepared in dried xerogels by an internal doping method. Mixed Cr/CdS phases were also prepared by internal loading of a chromium metal precursor. Following deposition of CdS the xerogel was heated at 120 °C under high vacuum, resulting in formation of intimately mixed phases of Cr metal and CdS. Changes in morphology, in particular the surface area and pore size distribution were noted. A decrease in surface area and an increase in pore size were observed as a result of Cr metal deposition.

Preparation and characterization of high-surface-area titanium dioxide by sol-gel process

2006 ◽  
Vol 13 (3-4) ◽  
pp. 251-258 ◽  
Author(s):  
Chaochin Su ◽  
Kuei-Fen Lin ◽  
Ya-Hui Lin ◽  
Bor-Hou You
Keyword(s):  
Titanium Dioxide ◽  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Sol Gel Process

Preparation and characterization of alumina membranes and alumina–titania composite membranes

1999 ◽  
Vol 14 (9) ◽  
pp. 3599-3603 ◽  
Author(s):  
Li Shi ◽  
Ning-Bew Wong
Keyword(s):  
Thermal Analysis ◽  
Particle Size ◽  
Differential Thermal Analysis ◽  
Sol Gel ◽  
Composite Membranes ◽  
Particle Sizes ◽  
Pore Sizes ◽  
Surface Areas ◽  
Alumina Membranes

Supported and unsupported γ-alumina membranes and alumina–titania composite membranes were prepared using the sol-gel method. In the course of preparation, effects of acid concentration, type of acid, alkoxide, and binder on the particle size of the sols and pore size of the membranes were investigated by thermogravimetry and differential thermal analysis, N2 physisorption, and light scattering. It was observed that the particle sizes of all the sols had only a small affect on the pore sizes of the membranes. Qualities of the membranes were improved by addition of polyvinyl alcohol as binder to the boehmite precursor. This resulted in less critical but more controllable drying and calcining procedures. Composite membranes with different pore sizes from 3.2 to 4.8 nm and surface areas retained above 100 m2/g could be regulated by different alumina-to-titania ratios.

Preparation and Characterization of Bi-Doped LaAlO3 via Sol-Gel Process

2012 ◽  
Vol 624 ◽  
pp. 30-33 ◽  
Author(s):  
Gui Fang Sun ◽  
Xi Wei Qi ◽  
Teng Zhang ◽  
Xiao Yan Zhang ◽  
Huan Huan Chen
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Infrared Absorption Spectrum ◽  
Sol Gel ◽  
Sem Analysis ◽  
Second Phase ◽  
Doping Content ◽  
Sol Gel Process ◽  
Bi Doping

A series of Bi-doped BixLa1-xAlO3 (x=0.0, 0.1, 0.2, 0.3, 0.4) powders have been prepared by sol-gel method at 800°C. The influences of Bi doping content on phase, morphology, particle size, surface area, infrared absorption spectrum are discussed. XRD results show that there is no second phase in powders when x≤0.3, however, there exist impure phases when x≥0.4. The SEM analysis indicates the particle size of powder is 50-150nm. The specific surface area is 5-13 m2/g.

scholarly journals Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1787
Author(s):  
Simon Carstens ◽  
Ralf Meyer ◽  
Dirk Enke
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Surface Areas ◽  
Alumina Membranes ◽  
Sol Gel Process ◽  
Specific Surface Areas ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16–24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

The Monolithic Silica Aerogel Derived from MTMS/TEOS

2013 ◽  
Vol 364 ◽  
pp. 631-634
Author(s):  
Yu Xi Yu ◽  
Yong Chen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Synthesis And Characterization ◽  
Sol Gel Process

The experimental results on the synthesis and characterization of tetraethoxysilane (TEOS)/ methyltrimethoxysilane (MTMS)-based silica aerogels using two step sol-gel process via supercritical drying, are described. The obtained TEOS/MTMS-based aerogel showed properties of 0.1g/cm3 density, 95.5% porosity and 1070 m2/g specific surface area.

Characterization of TiO2 Film Prepared by Sol-Gel Method Using Ti(OC4H9)4

2011 ◽  
Vol 298 ◽  
pp. 249-252 ◽  
Author(s):  
Li Li Yang ◽  
Jia Wei Bai ◽  
Wen Jie Zhang
Keyword(s):  
Pore Size ◽  
Tio2 Film ◽  
Average Pore Size ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Source Surface ◽  
Average Pore ◽  
Tio2 Particles ◽  
Sol Gel Process

TiO2 film was dip-coated on glass substrate by a sol-gel process. Ti(OC4H9)4 was used as the titanium source. Surface morphology, crystallite phase, UV-Vis transmittance spectrum and pore size distribution of TiO2 powder prepared under the same conditions of the film were investigated. Surface of TiO2 film is fairly smooth with very slight roughness. No obvious hole or pore is found on the surface of the film. The strongest diffraction peak situated at 2θ=25.3o is the characteristic of anatase TiO2. The absorption edge of the TiO2 film is around 350 nm, while the transmittance fluctuates between 50% and 90%. The average pore size of the TiO2 particles calculated by BJH method is 23 nm. The total pore volume and specific surface area are 0.16 ml/g and 27 m2/g, respectively.

Mesoporous crystalline SnO2 of large surface area

2003 ◽  
Vol 18 (12) ◽  
pp. 2890-2894 ◽  
Author(s):  
Chien-Yueh Tung ◽  
Nae-Lih Wu ◽  
I.A. Rusakova
Keyword(s):  
Heat Treatment ◽  
Surface Area ◽  
Pore Volume ◽  
Cetyltrimethylammonium Bromide ◽  
Sol Gel ◽  
Large Surface Area ◽  
Combined Process ◽  
Thermal Crystallization ◽  
Surface Areas ◽  
Sol Gel Process

Mesoporous crystalline SnO2 was synthesized by using templating process with cetyltrimethylammonium bromide as the template, combined with a pretreatment process of hexamethyldisilazane vapor prior to thermal crystallization. The combined process resulted in crystalline SnO2 exhibiting large pore volumes and surface areas that cannot be achieved by either of the processes alone, or by the conventional sol-gel process. Fully crystallized SnO2 powder with a pore volume of approximately 0.2 cc/g, a surface area of 220 m2/g, and mesopores mainly of 5 nm in diameter were obtained after heat treatment at 500°C.

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