Preparation of Superconducting YBa2Cu3O7−x Compounds By Water Extraction Variant Of Sol-Gel Process

1990 ◽  
Vol 180 ◽  
Author(s):  
A. Deptula ◽  
W. Lada ◽  
T. Olczak ◽  
T. zoltowski ◽  
A. Di Bartolomeo
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Ammonium Hydroxide ◽  
Water Extraction ◽  
Spherical Particles ◽  
Acidic Solutions ◽  
Sol Gel Process

ABSTRACTThe starting sols were prepared by addition of ammonium hydroxide to acidic solutions of Y-Ba-Cu acetates or by dissolving solid Ba9CO9 or CuCO9.CuCOH)2H2O in acetates of the remaining components. The sols were then gelled to spherical particles with diameter below 50μm by extracting water with 2-ethyl-l-hexanol or to shard by evaporation of water. After thermal treatment of both powders amorphous and then crystalline YBa2Cu,9O7−x were obtained. Formation of these compounds is strongly improved by aging the gel at 200°C. Green and sintered pellets exhibit excellent superconductivity properties.

Preparation of BSCCO Precursors by Water Extraction Variant of Sol-Gel Process

1992 ◽  
Vol 271 ◽  
Author(s):  
A. Deptula ◽  
W. Lada ◽  
T. Olczak ◽  
A. Di Bartolomeo
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Water Extraction ◽  
Sol Gel Process ◽  
Emulsion Drops ◽  
Preparation Step

ABSTRACTThe starling acetate sols of molar compositions of Bi:Pb:Sr:Ca:Cu=I-2:O:2:l: 2, 11–2:0:2:2:3 and 111–1.6:0.4:2:2:3 were prepared by NH4OH addition at various rates, followed by evaporation. Sols were gelled by further evaporation to shard or to microspheres (diameter below 100 μm) by water extraction from the sol emulsion drops formed in 2-ethyl-l-hexanol. The gels were converted to BSCCO phases by thermal treatment. The processes were characterized by XRD and IR examinations. The influence of the sol preparation step connected with formation of polynuclear cations on the following stages of the process was examined.

Spherical particles from tetraorthosilicate (TEOS) sol–gel process with dimethyldiethoxysilane (DDS) and diphenyldiethoxysilane (DPDS) addition

2008 ◽  
Vol 354 (45-46) ◽  
pp. 5047-5052 ◽  
Author(s):  
Fang Wang ◽  
Jianhong Liu ◽  
Hui Yang ◽  
Zhongkuan Luo ◽  
Weizhong Lv ◽  
...  
Keyword(s):  
Sol Gel ◽  
Spherical Particles ◽  
Sol Gel Process

Some Comments on the Production of Medium Sized Spherical Particles by Anion and Water Extraction Variant of Sol-Gel Process

1994 ◽  
Vol 372 ◽  
Author(s):  
A. Deptula ◽  
W. Łstoke;ada ◽  
T. Olczak ◽  
A. Chmielewski
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Extraction Process ◽  
Spherical Particles ◽  
Drastic Reduction ◽  
Sol Gel Process ◽  
Emulsion Drops ◽  
Clustering Effect ◽  
Non Destructive

AbstractMedium sized spherical particles (with diameters below 100 μm) of ceramic materials (Al203 and Al203 +8%TiO2) were produced in the following steps: (1) preparation of concentrated hydroxide sols of cations by extraction of anions using Primene JMT, (2) formation of sol emulsion in 2-ethylhexanol-1 containing various amounts of surfactants (EH), (3) gelation of emulsion drops by extraction of water with partially dehydrated EH, (4) non-destructive thermal treatment. Principal properties of the sol depend on the temperature of the extraction process. For preparation of lowanionic sols a two step extraction process, separated by digestion of the aqueous phase at boiling point, was necessary. It was found that the parameters of emulsion formation as well as the properties of the sols significantly influence the particle size distribution. It was concluded that lowering of the sol- EH interracial tension by the surfactant does not influence the process. On the contrary the “anti-clustering” effect of surfactants is essential for preparation of perfect spherical powders. The thermal decomposition of gels to oxides is determinant for densities, specific surface area and carbon content. Medium sized spherical powders are free flowing. The compactibility and sinterability of those powders are poor. However drastic reduction of particle size by milling (connected with their transformation to irregular shape) significantly improves the sinterability.

Improvement in Mechanical Property of SiO2 Films Prepared by Sol-Gel

2013 ◽  
Vol 744 ◽  
pp. 269-272 ◽  
Author(s):  
Pei Tao Guo
Keyword(s):  
Mechanical Property ◽  
Thermal Treatment ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Sol Gel ◽  
Dimethyl Formamide ◽  
Good Mechanical Property ◽  
Chemical Additives ◽  
Sol Gel Process ◽  
Silica Sols

Silica films prepared by the base catalyzed sol–gel process show poor mechanical property. In this study, silica anti-reflective films with good mechanical property have been prepared by the catalyzed sol–gel process with dimethyl formamide added as drying control chemical additives. The silica sol was first dip deposited onto substrate to form films on both sides of the substrate and then subjected to thermal treatment. After thermal treatment, the film was achieved due to the formation of porous structure in the resultant film as a result of decomposing tetraethylorthosilicate and dimethyl formamide. Nano-indenter measurement shows that the Young’s modulus and hardness of base catalyzed films are 10-20GPa and 0.25-0.55GPa, respectively. But the films added with dimethyl formamide are much better than those films derived from base-catalyzed silica sols, the Young’s modulus and hardness are 32-39GPa and 1.22-1.47GPa, respectively. The good mechanical properties make such films potential in both military and civil applications.

Study of Pseudoboehmite Synthesis by Sol-Gel Process

2006 ◽  
Vol 45 ◽  
pp. 260-265 ◽  
Author(s):  
Antônio Hortêncio Munhoz Jr. ◽  
Leila Figueiredo de Miranda ◽  
G.N. Uehara
Keyword(s):  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Sol Gel Synthesis

A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.

Sol-Gel Syntheses and Characterization of BaTi4O9 and BaTiO3-Powders

1988 ◽  
Vol 121 ◽  
Author(s):  
Pradeep P. Phule ◽  
Subhash H. Rkbud
Keyword(s):  
High Purity ◽  
Sol Gel ◽  
Spherical Particles ◽  
Barium Acetate ◽  
Amorphous Precursor ◽  
Sol Gel Process ◽  
Alkoxide Precursor ◽  
Precursor Powders ◽  
Hydrolysis Of

ABSTRACTSol-gel processes for the synthesis of high purity, ultrafine BaTi4O9 and BaTiO3 powders are described. Hydrolysis of an alkoxide precursor derived from barium metal and titanium (IV) isopropoxide resulted in formation of powders consisting of ultrafine (0.2 to 1.0 μm) spherical particles. These amorphous precursor powders were converted to crystalline BaTi4O9 powders (particle size 2–3 μm) by heat treatment at 1100 C. The sol-gel process for the synthesis of BaTiOj powders utilized chemical polymerization between moisture insensitive and relatively inexpensive barium acetate and titanium (IV) isopropoxide in the presence of acetic acid. The gel to ceramic conversion was achieved by firing the gels at 1000 °C to obtain high purity, stoichiometric BaTiO3 powders. The powders were sintered to obtain relatively dense (90 % relative density) ceramic bodies.

Effects of thermal treatment on the structure and luminescent properties of Eu 3+ doped SiO 2 –PMMA hybrid nanocomposites prepared by a sol–gel process

2016 ◽  
Vol 170 ◽  
pp. 588-593 ◽  
Author(s):  
Filipe Augusto de Jesus ◽  
Simei Tarse Sobrinho Santos ◽  
José Maurício Almeida Caiut ◽  
Victor Hugo Vitorino Sarmento
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Hybrid Nanocomposites ◽  
Sol Gel Process

Sintering of ZrO2 ‐ CeO2 Spherical Powders Prepared by a Water Extraction Variant of the Sol‐Gel Process

1993 ◽  
Vol 140 (8) ◽  
pp. 2294-2297 ◽  
Author(s):  
A. Deptula ◽  
M. Carewska ◽  
T. Olczak ◽  
W. Lada ◽  
F. Croce
Keyword(s):  
Sol Gel ◽  
Water Extraction ◽  
Sol Gel Process

Hollow Mullite Ceramic Microspheres by Water Extraction of Emulsified Aqueous Droplets

1994 ◽  
Vol 346 ◽  
Author(s):  
Guoxu Liu ◽  
David L. Wilcox
Keyword(s):  
Sol Gel ◽  
Model Material ◽  
Water Extraction ◽  
Microelectronic Packaging ◽  
Droplet Dispersion ◽  
Mullite Ceramic ◽  
Sol Gel Process ◽  
Potential Applications ◽  
Important Processing ◽  
Aqueous Droplet

ABSTRACTThis paper describes a novel colloidal route for the preparation of hollow mullite ceramic microspheres with sizes in the range of 10 μm. An emulsion technique was combined with a water extraction sol-gel process, to form an aqueous droplet dispersion and gel the resulting droplets by extracting water with a dehydrating liquid. The liquid-filled gelled microcapsules were then dried and fired to form hollow ceramic microspheres. Important processing variables controlling the microspherc morphology were determined and a formation mechanism was proposed. Due to its potential applications in microelectronic packaging, mullite was selected as the model material for the present work, but the synthesis technique may be used for making other single or multiphase ceramic compositions

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