Highly Mixed ZrO2/SiO2 Hybrid Aerogel Deriving from Freely Tangled Weakly Branched Primary Clusters Enables Improved Thermal Stability and Excellent Thermal Insulating Performance.

2019 ◽  
Author(s):  
Benxue Liu ◽  
Min Gao
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Sol Gel ◽  
Single Component ◽  
Thermal Stabilities ◽  
Crystallization Behaviors ◽  
Thermal Insulating ◽  
Enhanced Properties ◽  
Hybrid Aerogels ◽  
Hybrid Aerogel

In compared with single component aerogel, hybrid aerogel with multi-components possessing enhanced properties, especially high thermal stabilities which are our concerns in this paper, are the promised materials in various applications. However, how the mixing between variable components within hybrid aerogel affects their properties still not very clear and needs more research efforts. In the present research, we chose a ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogel as represent to study their mixing and the resulted thermal stabilities. We designed a series of ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogels with variable ZrO<sub>2</sub>/SiO<sub>2</sub> ratio deriving from tailored sol-gel parameters, and then studied their shrinkages, nanopore collapses and crystallization behaviors upon heat-treatment.

scholarly journals Highly Mixed ZrO2/SiO2 Hybrid Aerogel Deriving from Freely Tangled Weakly Branched Primary Clusters Enables Improved Thermal Stability and Excellent Thermal Insulating Performance.

2019 ◽  
Author(s):  
Benxue Liu ◽  
Min Gao
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Sol Gel ◽  
Single Component ◽  
Thermal Stabilities ◽  
Crystallization Behaviors ◽  
Thermal Insulating ◽  
Enhanced Properties ◽  
Hybrid Aerogels ◽  
Hybrid Aerogel

In compared with single component aerogel, hybrid aerogel with multi-components possessing enhanced properties, especially high thermal stabilities which are our concerns in this paper, are the promised materials in various applications. However, how the mixing between variable components within hybrid aerogel affects their properties still not very clear and needs more research efforts. In the present research, we chose a ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogel as represent to study their mixing and the resulted thermal stabilities. We designed a series of ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogels with variable ZrO<sub>2</sub>/SiO<sub>2</sub> ratio deriving from tailored sol-gel parameters, and then studied their shrinkages, nanopore collapses and crystallization behaviors upon heat-treatment.

Sol-gel Synthesis of Porous Crystalline TiO2–P2O5 Oxide with Thermal Stability

2003 ◽  
Vol 18 (12) ◽  
pp. 2743-2746 ◽  
Author(s):  
Donglin Li ◽  
Haoshen Zhou ◽  
Mitsuhiro Hibino ◽  
Itaru Honma
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Solid State ◽  
Block Copolymer ◽  
Specific Surface ◽  
Mixed Oxide ◽  
Glass Phase ◽  
Sol Gel ◽  
Anatase Structure ◽  
Sol Gel Synthesis

Porous TiO2–P2O5 oxide was synthesized by the sol-gel method in the presence of tri-block copolymer (EO)20(PO)70(EO)20 (Pluronic123) in queous solution. The TiO2 nanocrystals with anatase structure precipitated in the as-synthesized TiO2–P2O5 materials at 80°C, considerably lower than that for traditional heat treatment in the solid state, which maintained a stable size of 3.6–4 nm upon calcinations below 500°C. It is believed that P2O5 glass phase prevents the coarsening of TiO2 nanocrystals below 500°C. The mixed oxide exhibited a specific surface area of 170–200 m2/g after calcining in the temperature range of 300–500°C.

Preparation and Characterization of RF/SiO2 Hybrid Aerogel by Sol-Gel Method

2006 ◽  
Vol 11-12 ◽  
pp. 619-622 ◽  
Author(s):  
Xiao Hong Chen ◽  
Shuang Xi Yang ◽  
Huai He Song
Keyword(s):  
Raw Materials ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Ethanol Solution ◽  
Raw Material ◽  
Step Method ◽  
Wide Range ◽  
Hybrid Aerogels ◽  
Adsorption Desorption ◽  
Hybrid Aerogel

A novel organic and inorganic hybrid aerogel of RF/SiO2 is synthesized by one-step method of sol-gel polycondensation reaction using resorcinol-formaldehyde and tetramethoxysilane (TMOS) in ethanol solution, followed by supercritical drying with petroleum ether. The influence of the ratio of raw material on the structure and properties of samples was studied by high resolution electron microscope (HREM), nitrogen adsorption-desorption and infrared ray technology (IR). The results showed that the network structures of RF/SiO2 hybrid aerogels were constituted by an intercross framework of RF and SiO2. The hybrid aerogels can be tuned in bulk density from 0.098 g/cm3 to 0.062 g/cm3 according to the ratio of raw materials. The data of nitrogen adsorption-desorption showed that BET specific surface area was changed from 254 cm2/g to 545 cm2/g, and the pore size of aerogels was in the wide range of 2-10 nm. The investigation of IR spectrum analysis exhibited that there were no chemical bonds formed between SiO2 and RF aerogel.

scholarly journals Synthesis and Properties of Silica and Alginate Hybrid Aerogel Particles with Embedded Carbon Nanotubes (CNTs) for Selective Sorption

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 52 ◽  
Author(s):  
Natalia Menshutina ◽  
Pavel Tsygankov ◽  
Sviatoslav Ivanov
Keyword(s):  
Structural Characteristics ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Alginate Beads ◽  
Adsorption Selectivity ◽  
Volume Increase ◽  
Oil Emulsion ◽  
Hybrid Aerogels ◽  
Argon Adsorption ◽  
Hybrid Aerogel

The manuscript describes methods for producing hybrid silica microparticles and hybrid alginate beads with carbon nanotube (CNT) contents up to 4.5 and 30 wt.%, respectively. Silica hybrid aerogel microparticles with embedded nanotubes were obtained using a two-stage sol–gel method with a gelling process in an oil-emulsion. Alginate hybrid aerogels with embedded nanotubes were obtained using cross-linking reactions. The following methods were used to measure the structural characteristics of obtained materials: nitrogen adsorption porosimetry, scanning electron microscopy (SEM), and others. It is shown that specific surface area and pore volume increase with the increase of CNT content in silica aerogel microparticles. Obtained aerogels were tested as adsorbents for argon–oxygen separation. The alginate hybrid aerogel with 30 wt.% CNT content has the best argon adsorption selectivity.

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

scholarly journals Synthesis and photocatalytic properties of Sn–TiO2 nanomaterials

2020 ◽  
Vol 10 (01n02) ◽  
pp. 2060018
Author(s):  
E. M. Bayan ◽  
T. G. Lupeiko ◽  
L. E. Pustovaya ◽  
M. G. Volkova
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Sol Gel ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Light Activation ◽  
X Ray ◽  
Tio2 Nanomaterials ◽  
Visible Light Activation ◽  
Thermal Stability Of

Sn-doped TiO2 nanomaterials were synthesized by sol–gel method. It was shown the phase compositions and phase transitions change with the introduction of different tin amounts (0.5–20[Formula: see text]mol.%). X-ray powder diffraction was used to study the effect of different tin amounts on the anatase–rutile phase transition. It was found that the introduction of ions increases the thermal stability of anatase modifications. The material’s photocatalytic activity was studied in reaction with a model pollutant (methylene blue) photodegradation under UV and visible light activation. The best photocatalytic properties were shown for material, which contains 5[Formula: see text]mol.% of Sn.

Thermal stability of phase-separated nanograin structure during heat treatment

2021 ◽  
Vol 875 ◽  
pp. 160055
Author(s):  
Hua Guo ◽  
Fawei Tang ◽  
Yong Liu ◽  
Zhi Zhao ◽  
Hao Lu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Thermal Stability Of

LiNiO2 Thin Films Fabricated by Diffusion of Li on Ni Tapes

2007 ◽  
Vol 336-338 ◽  
pp. 505-508
Author(s):  
Cheol Jin Kim ◽  
In Sup Ahn ◽  
Kwon Koo Cho ◽  
Sung Gap Lee ◽  
Jun Ki Chung
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Grain Size ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Cold Isostatic Pressing ◽  
Tube Furnace ◽  
Treatment Conditions ◽  
Average Grain Size ◽  
Cold Rolling And Annealing

LiNiO2 thin films for the application of cathode of the rechargeable battery were fabricated by Li ion diffusion on the surface oxidized NiO layer. Bi-axially textured Ni-tapes with 50 ~ 80 μm thickness were fabricated using cold rolling and annealing of Ni-rod prepared by cold isostatic pressing of Ni powder. Surface oxidation of Ni-tapes were conducted using tube furnace or line-focused infrared heater at 700 °C for 150 sec in flowing oxygen atmosphere, resulted in NiO layer with thickness of 400 and 800 μm, respectively. After Li was deposited on the NiO layer by thermal evaporation, LiNiO2 was formed by Li diffusion through the NiO layer during subsequent heat treatment using IR heater with various heat treatment conditions. IR-heating resulted in the smoother surface and finer grain size of NiO and LiNiO2 layer compared to the tube-furnace heating. The average grain size of LiNiO2 layer was 0.5~1 μm, which is much smaller than that of sol-gel processed LiNiO2. The reacted LiNiO2 region showed homogeneous composition throughout the thickness and did not show any noticeable defects frequently found in the solid state reacted LiNiO2, but crack and delamination between the reacted LiNiO2 and Ni occurred as the reaction time increased above 4hrs.

Thermal Stabilities and the Thermal Degradation Kinetics Study of the Flame Retardant Epoxy Resins

2014 ◽  
Vol 1053 ◽  
pp. 263-267 ◽  
Author(s):  
Xiu Juan Tian
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Thermal Stabilities ◽  
Degradation Kinetic ◽  
Modified Epoxy

Thermal stability and thermal degradation kinetics of epoxy resins with 2-(Diphenylphosphinyl)-1, 4-benzenediol were investegated by thermogravimetric analysis (TGA) at different heating rates of 5 K/min, 10 K/min, 20 K/min and 40 K/min. The thermal degradation kinetic mechanism and models of the modified epoxy resins were determined by Coast Redfern method.The results showed that epoxy resins modified with the flame retardant had more thermal stability than pure epoxy resin. The solid-state decomposition mechanism of epoxy resin and the modified epoxy resin corresponded to the controlled decelerating ځ˽̈́˰̵̳͂͆ͅ˼˰̴̱̾˰̸̵̈́˰̵̸̳̱̹̽̾̓̽˰̶̳̹̾̈́̿̾̓ͅ˰̶˸ځ˹˰̵̵͇͂˰̃˸́˽ځ˹2/3. The introduction of phosphorus-containing flame retardant reduced thermal degradation rate of epoxy resins in the primary stage, and promote the formation of carbon layer.

Binding of 3-phosphoglycerate leads to both activation and stabilisation of ADP-glucose pyrophosphorylase from apple leaves

2005 ◽  
Vol 32 (9) ◽  
pp. 839
Author(s):  
Rui Zhou ◽  
Lailiang Cheng
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Enzyme Activity ◽  
Inorganic Phosphate ◽  
Thermal Inactivation ◽  
Specific Activity ◽  
Apple Leaves ◽  
Apparent Homogeneity ◽  
Adp Glucose Pyrophosphorylase ◽  
High Concentrations

Apple leaf ADP-glucose pyrophosphorylase was purified 1436-fold to apparent homogeneity with a specific activity of 58.9 units mg–1. The enzyme was activated by 3-phosphoglycerate (PGA) and inhibited by inorganic phosphate (Pi) in the ADPG synthesis direction. In the pyrophosphorolytic direction, however, high concentrations of PGA (> 2.5 mm) inhibited the enzyme activity. The enzyme was resistant to thermal inactivation with a T0.5 (temperature at which 50% of the enzyme activity is lost after 5 min incubation) of 52°C. Incubation with 2 mm PGA or 2 mm Pi increased T0.5 to 68°C. Incubation with 2 mm dithiothreitol (DTT) decreased T0.5 to 42°C, whereas inclusion of 2 mm PGA in the DTT incubation maintained T0.5 at 52°C. DTT-induced decrease in thermal stability was accompanied by monomerisation of the small subunits. Presence of PGA in the DTT incubation did not alter the monomerisation of the small subunits of the enzyme induced by DTT. These findings indicate that binding of PGA renders apple leaf AGPase with a conformation that is not only more efficient in catalysis but also more stable to heat treatment. The physiological significance of the protective effect of PGA on thermal inactivation of AGPase is discussed.

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