Stable nanocrystalline zirconia sols prepared by a novel method: Alcohol thermal synthesis

2000 ◽  
Vol 15 (2) ◽  
pp. 402-406 ◽  
Author(s):  
Junping Zhao ◽  
Wenhao Fan ◽  
Dong Wu ◽  
Yuhan Sun
Keyword(s):  
Hydrothermal Synthesis ◽  
Chemical Bonding ◽  
Sol Gel ◽  
Cubic Phase ◽  
Thermal Synthesis ◽  
Surface Areas ◽  
Sol Gel Process ◽  
Primary Particles ◽  
Novel Method ◽  
Nanocrystalline Zirconia

Nanocrystalline zirconia sols with a metastable cubic phase were synthesized from diglycol-modified zirconium n-propoxide via a novel method, alcohol thermal synthesis. The chemical bonding of diglycol with zirconium was found to be important in obtaining stable nanocrystalline zirconia sols. Sols produced in this way were translucent with the primary particles of 4-nm crystallites, and the corresponding gel was shown to be mesoporous with a pore size from 2.5 to 3.8 nm and Brunauer—Emmett—Teller surface areas between 130 and 266 m2 g−1. This indicates that alcohol thermal synthesis shares the advantages of both the sol-gel process and hydrothermal synthesis.

Preparation of Porous Silica by Microemulsion Coupling with Sol-Gel Method

2010 ◽  
Vol 113-116 ◽  
pp. 2266-2270
Author(s):  
Jing Li ◽  
Wei Xue ◽  
Yong Zhao ◽  
Zhi Miao Wang
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Tetraethyl Orthosilicate ◽  
Large Specific Surface Area ◽  
Silicon Source ◽  
Effect Of Solvent ◽  
Texture Properties ◽  
Sol Gel Process ◽  
Novel Method ◽  
Hcl Concentration

A novel method of microemulsion coupling with sol–gel process was used for preparation of porous silica using tetraethyl orthosilicate as silicon source. Effect of solvent and catalyst on the surface texture properties was investigated respectively. The results showed that porous silica with large specific surface area (738.65 m2/g) and high pore volume (2.01 cm3/g) was obtained. However, the mesopores in silica were arranged in disorder and showed great ununiformity in shape and arrangement. To obtain porous silica with desired texture properties, an appropriate dosage of ethanol and higher HCl concentration were needed.

Zirconium oxide nanoparticles coated on sepiolite by sol–gel process — Their application as a solvent-free catalyst for condensation reactions

2011 ◽  
Vol 89 (3) ◽  
pp. 280-288 ◽  
Author(s):  
Sadok Letaief ◽  
Yun Liu ◽  
Christian Detellier
Keyword(s):  
Clay Mineral ◽  
Zirconium Oxide ◽  
Condensation Reaction ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Solvent Free ◽  
Cubic Phase ◽  
Magic Angle ◽  
Solvent Free Conditions ◽  
Sol Gel Process

An inorganic nanocomposite made of zirconia nanoparticles coated on the external surfaces of the fibrous clay mineral sepiolite was prepared by using the sol–gel process under soft conditions using zirconium(IV) propoxide in 1-propanol as the precursor. The resulting materials were characterized by X-ray diffraction (XRD), thermal gravimetric analyses (TGA) and differential thermal analyses (DTA), microporosimetry, 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR), and high-resolution transmission electron microscopy (HR-TEM). The organic material from the precursor was fully removed after calcination at 450 °C, concurrently with the crystallization of the cubic phase of zirconium oxide. The coordinated water molecules of sepiolite were fully removed and its symmetrical layered structure was folded after calcination at 650 °C, as observed by XRD and 29Si cross-polarization (CP) / MAS NMR. The arrangement of the nanoparticles of zirconium oxide on the sepiolite external surfaces maintains a fibrous morphology for the nanocomposite. This material was applied as a catalyst for the Knoevenagel condensation reaction of benzaldehyde and malononitrile under solvent-free conditions. Strongly improved yields of reaction, attributed to larger catalytically active surfaces, were obtained compared with either the sepiolite clay mineral or the zirconium oxide tested individually.

A General Nonhydrolytic Sol‐Gel Route to Oxides

1994 ◽  
Vol 346 ◽  
Author(s):  
Sylvie Acosta ◽  
Pascal Arnal ◽  
Robert J.P. Corriu ◽  
Dominique Leclercq ◽  
P. Hubert Mutin ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
High Surface ◽  
Sol Gel ◽  
Metal Center ◽  
Binary Oxides ◽  
Surface Areas ◽  
Sol Gel Process ◽  
Silica Alumina ◽  
The One ◽  
Oxygen Donors

ABSTRACTA nonhydrolytic sol‐gel route based on the condensation between chlorides and oxygen donors such as ethers and alkoxides is presented. Four examples, silica, alumina, titania and binary oxides in the Al/Si system show that this is a general route. The mechanism of this condensation is completely different from the one of classical sol‐gel process, since it implies nucleophilic substitution at the carbon center instead of the metal center. As a consequence, the differences in reactivity between different metals are reduced. In addition, the structure of the precursors may be retained in the gel. Thus, the nonhydrolytic sol‐gel process is very efficient for the preparation of homogeneous bicomponent oxides. Futhermore, nonhydrated gels are formed, which allowed us to prepare amorphous aluminas with high surface areas.

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.

scholarly journals Thermal resilience of ensilicated lysozyme via calorimetric and in vivo analysis

RSC Advances ◽  
2020 ◽  
Vol 10 (50) ◽  
pp. 29789-29796
Author(s):  
A. Doekhie ◽  
M. N. Slade ◽  
L. Cliff ◽  
L. Weaver ◽  
R. Castaing ◽  
...  
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Silica Shell ◽  
Room Temperature Storage ◽  
Sol Gel Process ◽  
In Vivo Analysis ◽  
Novel Method ◽  
Temperature Storage

Ensilication is a novel method of protein thermal stabilisation using silica. It uses a modified sol–gel process which tailor fits a protective silica shell around the protein to enable room temperature storage of biopharmaceuticals.

Phase structure and thermal evolution in coatings and powders obtained by the sol-gel process: Part I. ZrO2−11.3 mol% Y2O3

1997 ◽  
Vol 12 (2) ◽  
pp. 493-500 ◽  
Author(s):  
P. C. Rivas ◽  
M. C. Caracoche ◽  
J. A. Martínez ◽  
A. M. Rodríguez ◽  
R. Caruso ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Thermal Evolution ◽  
Sol Gel ◽  
Correlation Spectroscopy ◽  
Cubic Phase ◽  
Perturbed Angular Correlation Spectroscopy ◽  
Heating And Cooling ◽  
Sol Gel Process ◽  
Fast Movement ◽  
Zirconia Powders

Yttria-stabilized cubic zirconia powders and coatings produced by the sol-gel method have been investigated by Perturbed Angular Correlation Spectroscopy (PAC). Results indicate that the metastable cubic phase is retained during heating and cooling cycles. The hyperfine interaction that describes this cubic phase, once crystallized, exhibits two components in a constant ratio of 4 : 1. The components represent different vacancy configurations. For the fast movement of oxygen vacancies starting at 750 °C, which is reflected by the damping of the hyperfine pattern, an activation energy of 0.96 eV was determined.

Preparation of t-ZrO2 by a sol–gel process with carbon as a phase transformation promoter

RSC Advances ◽  
2015 ◽  
Vol 5 (43) ◽  
pp. 34451-34455 ◽  
Author(s):  
Yu Liu ◽  
Weidong Chi ◽  
Hui Liu ◽  
Yueyang Su ◽  
Liang Zhao
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Amorphous Carbon ◽  
Sol Gel ◽  
Cubic Phase ◽  
Sol Gel Process

Cubic phase ZrO2 can be synthesized with amorphous carbon as a phase transition promoter.

Surface chemical bonding states and ferroelectricity of Ce-doped BiFeO3 thin films prepared by sol–gel process

2008 ◽  
Vol 48 (3) ◽  
pp. 261-266 ◽  
Author(s):  
Zuci Quan ◽  
Hao Hu ◽  
Sheng Xu ◽  
Wei Liu ◽  
Guojia Fang ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Bonding ◽  
Sol Gel ◽  
Surface Chemical ◽  
Bifeo3 Thin Films ◽  
Sol Gel Process

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.

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