Synthesis and Characterization of Hydrotalcites: [Zn1−xAlx(OH)2](CO3)x/2·mH2O; x=0.25−0.66

1996 ◽  
Vol 454 ◽  
Author(s):  
M. A. Valenzuela ◽  
E. López-Salinas ◽  
B. Zapata ◽  
J. A. Montoya
Keyword(s):  
Thermal Treatment ◽  
Specific Surface ◽  
Calcination Temperature ◽  
Layered Structure ◽  
Synthesis And Characterization ◽  
Surface Areas ◽  
Constant Ph ◽  
Specific Surface Areas ◽  
Pure Phases

ABSTRACTIn this work a series of [Zn1−xAlx(OH)2](CO3)x/2·mH2O; x=0.25−0.66 were prepared at constant pH in order to study the effect of the thermal treatment on their crystalline srtucture. It was found that is possible to obtain pure Zn-Al hydrotalcite materials within a x = 0.25−0.50 range in comparison with Mg-Al hydrotalcites which yield pure phases in more restricted x ranges (0.25−0.33). All Zn-Al hydrotalcites lost their layered structure at temperatures above 473 K being less stable than their parental Mg-Al hydotalcite (623 K). Specific surface areas of these materials depended strongly on the Zn/Al ratio and calcination temperature, ranging from 280 to 20 m2/g. ZnO and ZnAl2O4 compounds were detected as the calcination products at temperatures higher than 873 K.

Preparation and characterization of titanium oxynitrides with high specific surface areas

1991 ◽  
Vol 95 (1) ◽  
pp. 145-155 ◽  
Author(s):  
Chae Ho Shin ◽  
Guy Bugli ◽  
Gerald Djega-Mariadassou
Keyword(s):  
Specific Surface ◽  
Surface Areas ◽  
Specific Surface Areas

A strategy for the synthesis of VN@C and VC@C core–shell composites with hierarchically porous structures and large specific surface areas for high performance symmetric supercapacitors

2018 ◽  
Vol 47 (24) ◽  
pp. 8052-8062 ◽  
Author(s):  
Yifu Zhang ◽  
Jiqi Zheng ◽  
Xuyang Jing ◽  
Changgong Meng
Keyword(s):  
Thermal Treatment ◽  
Electrochemical Performance ◽  
Specific Surface ◽  
High Performance ◽  
Core Shell ◽  
Porous Structures ◽  
Hierarchically Porous ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Novel Strategy

A novel strategy for the fabrication of VN@C and VC@C was developed by the thermal treatment with H2V3O8@C under N2 and Ar atmospheres. VN@C SSC device exhibited better electrochemical performance than VC@C SSC device.

scholarly journals Effect of Imposed Shear Strain on Steel Ring Surfaces during Milling in High-Speed Disintegrator

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2234 ◽  
Author(s):  
Karel Dvořák ◽  
Adéla Macháčková ◽  
Simona Ravaszová ◽  
Dominik Gazdič
Keyword(s):  
Specific Surface ◽  
High Speed ◽  
Relative Increase ◽  
Coarse Particles ◽  
Cement Sample ◽  
Surface Areas ◽  
Original Mass ◽  
Specific Surface Areas ◽  
Ground Material

This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.

scholarly journals Possibility of Using t-Plots, Obtained from Nitrogen Adsorption for the Valuation of Zeolites

1986 ◽  
Vol 3 (3) ◽  
pp. 159-166 ◽  
Author(s):  
P. Hudec ◽  
J. Novanský ◽  
S. Silhár ◽  
T. N. Trung ◽  
M. Zúbek ◽  
...  
Keyword(s):  
Specific Surface ◽  
Quantitative Estimation ◽  
Nitrogen Adsorption ◽  
Surface Areas ◽  
Bet Analysis ◽  
Zeolite Content ◽  
Synthetic Zeolites ◽  
Specific Surface Areas ◽  
Specific Volumes

Data of adsorption isotherms of nitrogen adsorption at 77 K on various samples of zeolites were measured. Besides derivation of specific surface area by BET analysis, samples were characterised by values obtained by t-plots; specific surface areas of mesopores and specific volumes of micropores are also calculated. Results show the value of the use of t-plot method for the characterization of microporosity changes in zeolites after various treatments, and also for quantitative estimation of zeolite content in natural zeolites and the crystallinity of synthetic zeolites.

The Formation and Characterization of Poly (p-phenylene benzobisoxazole) Pulps via Stirred Solutions

2015 ◽  
Vol 1120-1121 ◽  
pp. 620-623
Author(s):  
Rong Biao Liu ◽  
Xin Xin Li ◽  
Jun Qian ◽  
Zhe Wen Han
Keyword(s):  
Specific Surface ◽  
Electron Micrographs ◽  
Methanesulfonic Acid ◽  
Scanning Electron Micrographs ◽  
Short Fibers ◽  
Surface Areas ◽  
Stirring Time ◽  
Specific Surface Areas ◽  
Scanning Electron

PBO (p-phenylene benzobisoxazole) short fibers, attached fine fibrils that are called PBO pulp, may precipitate directly from stirred PBO/methanesulfonic acid (MSA) solution by the use of water coagulant in fibrous pulp form. Scanning electron micrographs show that the precipitated PBO pulps have a ribbon-like structure similar to Kevlar pulps. The thermalgravimetric analysis (TGA) show there were no appreciable mass changes until 550 °C in the air. The process yields PBO pulps with different specific surface areas (SSA) depending on the stirring speed, stirring time and the concentration of the PBO/MSA solution. High SSA PBO pulps can be produced by increasing the stirring speed, prolonging the stirring time and reducing the concentration of the PBO/MSA solution.

Synthesis and characterization of layered bismuth vanadates

1990 ◽  
Vol 5 (11) ◽  
pp. 2718-2722 ◽  
Author(s):  
K. B. R. Varma ◽  
G. N. Subbanna ◽  
T. N. Guru ◽  
C. N. R. Rao
Keyword(s):  
Curie Temperature ◽  
General Formula ◽  
Layered Structure ◽  
Synthesis And Characterization ◽  
Structure And Properties ◽  
Bismuth Vanadates

Bi2VO5.5 (Bi4O11), which is the vanadium analog of the first member of the Aurivillius family of oxides of the general formula Bi2An−1BnO3n+3, has been prepared and characterized. The vanadate has the expected layered structure and is ferroelectric with a Curie temperature of 720 K. While we have not been able to synthesize the vanadium analog of the n = 2 member of the Aurivillius family, we have examined the structure and properties of a vanadate of the composition Bi2V3O9.

scholarly journals Ultrafine porous boron nitride nanofibers synthesized via a freeze-drying and pyrolysis process and their adsorption properties

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1253-1259 ◽  
Author(s):  
Jing Lin ◽  
Lulu Xu ◽  
Yang Huang ◽  
Jie Li ◽  
Weijia Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Specific Surface ◽  
Freeze Drying ◽  
Adsorption Properties ◽  
Pyrolysis Process ◽  
Surface Areas ◽  
Aspect Ratios ◽  
Large Pore ◽  
Specific Surface Areas

Ultrafine porous boron nitride nanofibers with high aspect ratios, high specific surface areas and large pore volumes has been synthesized in large quantity via a freeze-drying and post pyrolysis process.

scholarly journals Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Gang Zhou ◽  
Han Qiu ◽  
Qi Zhang ◽  
Mao Xu ◽  
Jiayuan Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Specific Surface ◽  
Coal Dust ◽  
Single Point ◽  
Contact Angles ◽  
Critical Surface ◽  
Volume Percentage ◽  
Surface Areas ◽  
Specific Surface Areas

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Facile Method To Synthesize Mesoporous Multimetal Oxides (ATiO3, A = Sr, Ba) with Large Specific Surface Areas and Crystalline Pore walls

2010 ◽  
Vol 22 (4) ◽  
pp. 1276-1278 ◽  
Author(s):  
Xiaoxing Fan ◽  
Ying Wang ◽  
Xinyi Chen ◽  
Ling Gao ◽  
Wenjun Luo ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Areas ◽  
Specific Surface Areas
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