scholarly journals Synthesis and characterization of novel porous La2Zr2O7 ceramic with ultralow thermal conductivity and excellent photocatalytic property

2021 ◽  
Author(s):  
Baosehng Xu ◽  
Debao LIU ◽  
Liyan GENG ◽  
Feifei ZHOU ◽  
Lijie QU ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Phase ◽  
Dye Degradation ◽  
Sol Gel ◽  
Structural Evolution ◽  
Photocatalytic Property ◽  
Mesoporous Structure ◽  
Calcination Process ◽  
Surface Areas

Abstract A novel porous La2Zr2O7 ceramic prepared by combining a sol-gel template method and high-temperature calcination process. The structural evolution and crystallisation behaviour of the samples were systematically characterized using SEM, XRD, TEM and Raman spectroscopy. The results indicated that the as-prepared porous La2Zr2O7 ceramic had a typical nanoparticles assembling and mesoporous structure with single-phase pyrochlore crystal structure. Meanwhile, the as-prepared porous La2Zr2O7 ceramic presented an ultralow room temperature thermal conductivity of 0.07 W/(m·K), high specific surface areas of 325.17 m2/g and a relatively high compressive strength of 11.95 MPa. What’s more, the as-prepared porous La2Zr2O7 ceramic possessed ideal photocatalytic activity owing to the unique 3-D porous structure, high crystallinity and large surface area. These reported studies are proposing some new insight to improve porous rare-earth zirconates ceramic for thermal insulation and dye degradation applications.

Fabrication and Characterization of Sol-Gel Derived PZT/WO3 Ceramics

2008 ◽  
Vol 55-57 ◽  
pp. 369-372 ◽  
Author(s):  
T. Sreesattabud ◽  
Anucha Watcharapasorn ◽  
Sukanda Jiansirisomboon
Keyword(s):  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Rhombohedral Phase ◽  
Lead Zirconate ◽  
X Ray Diffraction ◽  
Calcination Process ◽  
Materials Used ◽  
Phase Characterization ◽  
Gel Processing

Lead zirconate titanate/tungsten oxide (PZT/WO3) ceramics were prepared from the powders synthesized by a modified triol sol-gel processing method. In this study, the starting materials used for synthesis of PZT-sol were zirconium (IV) propoxide, titanium (IV) isopropxide, lead (II) acetate trihydrate and 1,1,1,- tris (hydroxymethyl) ethane. To prepare PZT/xWO3 powders (where x = 0, 0.5, 1 and 3 wt%), nano-sized WO3 was ultrasonically dispersed and mixed with the PZT sol, dried and calcined at 600°C for 4 h. X-ray diffraction results indicated that fully crystallized powders were obtained. Phase characterization suggested that at high WO3 concentration, the reaction between PZT and WO3 occurred during the calcination process. To prepare PZT/xWO3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the content of WO3 significantly affected tetragonal-to-rhombohedral phase transition. Microstructure of thermally etched samples showed that increasing the content of WO3 decreased grain size of the ceramics.

Low-temperature processing and characterization of single-phase PZT powders by sol-gel method

2007 ◽  
Vol 42 (23) ◽  
pp. 9801-9806 ◽  
Author(s):  
Radhouane Bel Hadj Tahar ◽  
Noureddine Bel Hadj Tahar ◽  
Abdelhamid Ben Salah
Keyword(s):  
Low Temperature ◽  
Single Phase ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Low Temperature Processing

scholarly journals Hydrocracking of Polyethylene to Jet Fuel Range Hydrocarbons over Bifunctional Catalysts Containing Pt- and Al-Modified MCM-48

Reactions ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 195-209
Author(s):  
Yanyong Liu
Keyword(s):  
Mesoporous Silica ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Jet Fuel ◽  
Magic Angle Spinning ◽  
High Yield ◽  
Magic Angle ◽  
Surface Areas ◽  
Angle Spinning ◽  
Post Modification

A low-density polyethylene was hydrocracked to liquid hydrocarbons in autoclave reactors over catalysts containing Pt- and Al-modified MCM-48. Two kinds of Al-modified MCM-48 were synthesized for the reaction: Al-MCM-48 was synthesized using a sol–gel method by mixing Al(iso-OC3H7)3 with Si(OC2H5)4 and surfactant in a basic aqueous solution before hydrothermal synthesis, and Al/MCM-48 was synthesized using a post-modification method by grafting Al3+ ions on the surface of calcined Al/MCM-48. X-ray diffraction (XRD) patterns indicated that both Al-MCM-48 and Al/MCM-48 had a cubic mesoporous structure. The Brunauer–Emmett–Teller (BET) surface areas of Al-MCM-48 and Al/MCM-48 were larger than 1000 m2/g. 27Al Magic Angle Spinning-NMR (MAS NMR) indicated that Al3+ in Al-MCM-48 was located inside the framework of mesoporous silica, but Al3+ in Al/MCM-48 was located outside the framework of mesoporous silica. The results of ammonia temperature-programmed desorption (NH3-TPD) showed that the acidic strength of various samples was in the order of H-Y > Al/MCM-48 > Al-MCM-48 > MCM-48. After 4 MPa H2 was charged in the autoclave at room temperature, 1 wt % Pt/Al/MCM-48 catalyst showed a high yield of C9−C15 jet fuel range hydrocarbons of 85.9% in the hydrocracking of polyethylene at 573 K for 4 h. Compared with the reaction results of Pt/Al/MCM-48, the yield of light hydrocarbons (C1−C8) increased over Pt/H-Y, and the yield of heavy hydrocarbons (C16−C21) increased over Pt/Al-MCM-48 in the hydrocracking of polyethylene. The yield of C9−C15 jet fuel range hydrocarbons over the used catalyst did not decrease compared to the fresh catalyst in the hydrocracking of polyethylene to jet fuel range hydrocarbons over Pt/Al/MCM-48.

scholarly journals A Structural Comparison of Ordered and Non-Ordered Ion Doped Silicate Bioactive Glasses

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 992
Author(s):  
Seray Schmitz ◽  
Ana M. Beltrán ◽  
Mark Cresswell ◽  
Aldo R. Boccaccini
Keyword(s):  
Metal Ion ◽  
Sol Gel ◽  
Glass Network ◽  
Textural Properties ◽  
Mesoporous Structure ◽  
Structure Directing Agent ◽  
Surface Areas ◽  
Pluronic P123 ◽  
Gel Glasses ◽  
The One

One of the key benefits of sol-gel-derived glasses is the presence of a mesoporous structure and the resulting increase in surface area. This enhancement in textural properties has a significant effect on the physicochemical properties of the materials. In this context the aim of this study was to investigate how sol-gel synthesis parameters can influence the textural and structural properties of mesoporous silicate glasses. We report the synthesis and characterization of metal ion doped sol-gel derived glasses with different dopants in the presence or absence of a surfactant (Pluronic P123) used as structure-directing templating agent. Characterization was done by several methods. Using a structure directing agent led to larger surface areas and highly ordered mesoporous structures. The chemical structure of the non-ordered glasses was modified to a larger extent than the one of the ordered glasses due to increased incorporation of dopant ions into the glass network. The results will help to further understand how the properties of sol-gel glasses can be controlled by incorporation of metal dopants, in conjunction with control over the textural properties, and will be important to optimize the properties of sol-gel glasses for specific applications, e.g., drug delivery, bone regeneration, wound healing, and antibacterial materials.

Synthesis and Characterization of Mesoporous Silica Nanoparticles Embedded Gadolinium Oxide

2011 ◽  
Vol 306-307 ◽  
pp. 1275-1279 ◽  
Author(s):  
Ning Qi Luo ◽  
Zhan Yun Huang ◽  
Ping Luo ◽  
Yuan Zhi Shao ◽  
Di Hu Chen
Keyword(s):  
Mesoporous Silica ◽  
Self Assembly ◽  
Mesoporous Silica Nanoparticles ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Gadolinium Oxide ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
The Mean

We first synthesized gadolinium oxide (Gd2O3) by a modified “polyol” strategy and then embedded it into mesoporous silica by a simple self-assembly sol-gel reaction. Scanning electron microscope (SEM) results show that the samples have good sphericity and good dispersibility. The structure of mesoporous silica was characterized by transmission electron microscopy (TEM) and small-angle X-ray diffraction (SAXRD). Results show that the mesoporous structure has not been destroyed after gadolinium oxide imbedding. The ratio of gadolinium and silica was determined by the mean of energy dispersive spectroscopy (EDS).

A Calcination Technology for Ultrafine La3NbO7 Powder Prepared by Sol-Gel Process

2011 ◽  
Vol 412 ◽  
pp. 271-274
Author(s):  
Ying Li ◽  
Qiang Xu ◽  
Ling Dai
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Average Particle Size ◽  
Complex Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Acid Complex ◽  
Calcination Process ◽  
Sol Gel Process

In order to prepare ultrafine La3NbO7 powder, a potential material for thermal barrier coatings, the calcination process of La3NbO7 was studied in this paper.The precursor of La3NbO7 was synthesized by using a citric acid complex method. A calcination process had been systematically investigated. The reaction temperature was determined by differential scanning calorimetry (DSC). The phase composition of powders was characterized by X-ray diffraction (XRD), and the morphology was obtained by scanning electron microscope (SEM). The results revealed that the single-phase La3NbO7 powder could be successfully prepared while the calcination temperature exceeded 800°C and a better morphology could be maintained at 800°C for 4 hours. Considering all above, an optimum calcination scheme was adopted at 800°C for 4 hours. The as-prepared La3NbO7 powders had a grain size of about 50nm and an average particle size of about 300nm.

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 Evaluation of the photocatalytic ability of a sol-gel-derived MgO-ZrO2 oxide material

2017 ◽  
Vol 15 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Filip Ciesielczyk ◽  
Weronika Szczekocka ◽  
Katarzyna Siwińska-Stefańska ◽  
Adam Piasecki ◽  
Dominik Paukszta ◽  
...  
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Oxide Material ◽  
Particle Sizes ◽  
Characteristic Functional ◽  
Photocatalytic Ability ◽  
Calcination Process ◽  
Organic Precursors

AbstractThis paper deals with the synthesis and characterization of a novel group of potential photocatalysts, based on sol-gel-derived MgO-ZrO2 oxide material. The material was synthesized in a typical sol-gel system using organic precursors of magnesia and zirconia, ammonia as a promoter of hydrolysis and methanol as a solvent. All materials were thoroughly analyzed, including morphology and particle sizes, chemical composition, identification of characteristic functional groups, porous structure parameters and crystalline structure. The proposed methodology of synthesis resulted in obtaining pure MgO-ZrO2 oxide material with micrometric-sized particles and a relatively high surface area. The samples underwent an additional calcination process which led to the crystalline phase of zirconia being formed. The key element of the study was the evaluation of the effectiveness of decomposition of C.I. Basic Blue 9 dye. It was shown that the calcined materials exhibit both satisfactory adsorption and photocatalytic activity with respect to the decomposition of a selected model organic impurity. Total dye removal varied in the range of 50-70%, and was strongly dependent on process parameters such as quantity of photocatalyst, time of irradiation, and the addition of promoters.

scholarly journals Fabrication and Characterization of CoFe2O4/CoFe2/SiO2 Nanocomposite Particles

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Tran Thi Viet Nga
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Sol Gel ◽  
Calcination Time ◽  
Nanocomposite Particles ◽  
X Ray ◽  
Fabrication And Characterization ◽  
Xrd Patterns ◽  
20 Nm

The CoFe2O4/CoFe2/SiO2 nanocomposite particles were synthesized using a sol- gel method and calcination in hydrogen. The magnetic properties and structure of nanocomposite particles calcinated at 600 oC and 900 oC in range of calcination time from 1 h to 4 h were investigated. The phase composition, surface morphology and magnetic properties of the nanocomposites were investigated using X-ray powder diffraction, scanning electron microscopy and vibrating sample magnetometer. The XRD patterns indicate the existence of both CoFe2O4 and CoFe2 phases in the nanocomposite after reducing at 600 oC for 2 h and 3 h. The single phase CoFe2 was obtained after reducing at 900 oC. The average particles size was evenly distributed in the range of 20 nm to 120 nm. The magnetization increases significantly with increasing of reduction temperature.

scholarly journals Synthesis and Characterization of a Highly Ordered Mesoporous Bio-glass

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Bui Xuan Vuong ◽  
Ngo Thi My Thanh
Keyword(s):  
Body Fluid ◽  
Glass Powder ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
In Vitro Experiment ◽  
Pluronic P123 ◽  
Ordered Mesoporous ◽  
Synthetic Biomaterial

A highly ordered mesoporous bio-glass has been successfully prepared by the sol-gel method, in which copolymer pluronic P123 was used as a structure-creating template. The obtained material has the mesoporous structure with the high value of specific surface area (395.6 m2 /g) and the 2D hexagonal pore architecture with the pore sizes from 5.5 to 7 nm. The ‘‘in vitro’’ experiment was effectuated by soaking the bio-glass powder in the simulated body fluid (SBF). The obtained results confirmed the bioactivity of the synthetic biomaterial through the quick formation of a hydroxyapatite layer after 1 day of immersion. Keywords: Bio-glass, pore size, mesoporous, bioactivity, ‘‘in vitro’’.  

Sign in / Sign up

Export Citation Format

Share Document