Preparation and Characterization of Sodium Hexatitanate Whiskers

2012 ◽  
Vol 602-604 ◽  
pp. 1339-1343
Author(s):  
Xiao Yu Zhang ◽  
Yu Jun Zhang ◽  
Hong Yu Gong ◽  
Yun Na Song
Keyword(s):  
Aspect Ratio ◽  
Heating Temperature ◽  
Average Diameter ◽  
Potassium Fluoride ◽  
Growth Behavior ◽  
Molar Ratio ◽  
Morphological Observation ◽  
Industrial Grade

Sodium hexatitanate (Na2O•6TiO2) whiskers with an average diameter and aspect ratio of 1-3 µm and 10-20 respectively were synthesized by calcinating mixtures of industrial grade sodium carbonate (Na2CO3), anatase TiO2 and potassium fluoride (KF). The growth of sodium hexatitanate whiskers was obtainable in a range of TiO2/Na2CO3 molar ratio from 4 to 6, heating temperature from 940 °C to 1000 °C and content of KF from 5 wt.% to 7 wt.% with different morphologies and aspect ratio of the products. The role of KF on the growth behavior of Na2O•6TiO2 whiskers was demonstrated by structural and morphological observation.

scholarly journals In Situ Growth Behavior of SiC Whiskers with High Aspect Ratio in the Synthesis of ZrB2-SiC Composite Powders

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3502 ◽  
Author(s):  
Xiaoqing Lian ◽  
Xiaohu Hua ◽  
Xiaogang Wang ◽  
Lirong Deng
Keyword(s):  
Electron Microscopy ◽  
Aspect Ratio ◽  
Molten Salt ◽  
Heating Temperature ◽  
Growth Behavior ◽  
Molar Ratio ◽  
Composite Powders ◽  
X Ray ◽  
Sic Whiskers

Aiming to provide key materials in order to improve the fracture toughness of ZrB2 ceramics, ZrB2-SiC composite powders with in situ grown SiC whiskers were successfully synthesized via a simple molten-salt-assisted ferrous-catalyzed carbothermal reduction method. Thermodynamic calculations on the ZrO2-SiO2-B2O3-C-Fe system were carried out. The effects of heating temperature and ferrous catalyst amount on the growth behavior of SiC whiskers in ZrB2-SiC composite powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results showed that the aspect ratio of SiC whiskers and the relative content of ZrB2 particles increased with increasing heating temperature (1523–1723 K) and a molar ratio of Fe to ZrSiO4 from 0:1 to 0.2:1. Phase-pure ZrB2-SiC composite powders were obtained at 1723 K when the molar ratio of raw materials was 0.2:0.5:1:1.5:8.4 (Fe:NaCl:ZrSiO4:B2O3:C). Single crystalline β-SiC whiskers with a mean diameter of 0.15 μm and an aspect ratio of 70–120 were homogeneously distributed in the final composite powders. A molten-salt-assisted iron-catalyzed vapor–solid mechanism was promoted for the growth mechanism of in situ grown SiC whiskers.

Preparation and characterization of poly(styrenemethacrylic acid)/MCM-41 core/shell nanocomposite microspheres

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Yansheng Zhao ◽  
Xingji Ma ◽  
Yongmei Liu ◽  
Guangwei Yuan ◽  
Meijuan Guo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Cetyltrimethylammonium Bromide ◽  
Average Diameter ◽  
Molar Ratio ◽  
Core Shell ◽  
Acidic Media ◽  
Assembly Method ◽  
20 Nm ◽  
Mcm 41

AbstractIn acidic media, poly(styrene-methacrylic acid)/MCM-41 [P(St- MAA)/MCM-41] core/shell microspheres were synthesized using monodisperse P(St-MAA) particles contained in soap-free emulsion and cetyltrimethylammonium bromide as co-templates by adsorption self-assembly method. The effects of P(St- MAA) composition on shell structure of the core/shell microspheres were investigated. The morphology and composition of P(St-MAA)/MCM-41 microspheres were characterized by TEM, XRD and FTIR. The results show that the ordering degree of MCM-41 shells increased as the molar ratio of MAA to St increased. When n(MAA)/n(St) is 0.2, the average diameter and the shell thickness of nanocomposite microspheres are about 170 nm and 20 nm, respectively.

The Role of Crystal Control Agent in the Formation of Needlelike Calcium Carbonate Nano Particles

2011 ◽  
Vol 236-238 ◽  
pp. 2150-2159
Author(s):  
Yu Qian Ye ◽  
Xue Mei Chen
Keyword(s):  
Calcium Carbonate ◽  
Aspect Ratio ◽  
Crucial Role ◽  
Average Diameter ◽  
Morphological Characterization ◽  
Control Agent ◽  
Nano Particles ◽  
Precipitated Calcium Carbonate ◽  
Nanometer Particles

In this work, needlelike precipitated calcium carbonate (PCC) nanometer particles were synthesized by industrial carbonation route using EDTA as crystal control agent. The morphological characterization shows that the as-synthesized needlelike PCC particles have an average diameter of 52 nm and an aspect ratio of around 14:1. The results indicate that EDTA plays a crucial role in the formation of needlelike PCC nanometer particles. A possible mechanism for the formation of needlelike PCC particles assisted by the crystal control agent EDTA is also proposed.

Synthesis and Characterization of YCrxAl1-xO3 Particles by a Reverse Micelle Processing

2017 ◽  
Vol 47 ◽  
pp. 54-59 ◽  
Author(s):  
Dae Han Lee ◽  
Ji Young Ock ◽  
Jeong Hoon Son ◽  
Dong Sik Bae
Keyword(s):  
Reverse Micelle ◽  
Heating Temperature ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Inorganic Pigment ◽  
X Ray ◽  
Heat Treated ◽  
Average Size

YCrxAl1-xO3 nanoparticles were synthesized by a reverse micelle processing for inorganic pigment. Y(NO3)2·6H2O, Cr (NO3)2·6H2O and Al (NO3)3·9H2O are used for precursors in order to synthesis YCrxAl1-xO3 nanoparticles. The aqueous solution consists of mixing the molar ratio of Y/Cr/Al at 1:x:1-x and heat treated at 900~1300°C for 2h. The average size and distribution of synthesized YCrxAl1-xO3 powders was in the range of 10-20nm and narrow, respectively. The average size of the synthesized YCrxAl1-xO3 powders increased with increasing water to surfactant molar ratio and heating temperature. The crystallinity of synthesized YCrxAl1-xO3 powder increased with increasing heating temperature. The synthesized YCrxAl1-xO3 powders were characterized by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM) and color spectrophotometer. The properties of the synthesized powders were affected by such variables as molar ratio, heating temperature etc.

Synthesis and Characterization of Flower-Like Hematite Nanostructures

2011 ◽  
Vol 287-290 ◽  
pp. 169-172
Author(s):  
Hong Wang ◽  
Xi Yang He ◽  
Ying Wang
Keyword(s):  
Electron Microscopy ◽  
Average Length ◽  
Critical Role ◽  
Average Diameter ◽  
Synthesis And Characterization ◽  
Hydrothermal Route ◽  
X Ray ◽  
Scanning Electron

The flower-like α-Fe2O3superstructures were fabricated by a novel hydrothermal route and sequential annealing at 600 °C for 1 h using FeCl3×6H2O as the starting precursor. The structures and morphologies of the synthesized flower-like superstructures have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM). It is revealed that the flower-like α-Fe2O3nanostructures consist of nanorods with the average diameter of about 70 nm and an average length of about 200nm growing from the centers. The critical role of urea in the hydrothermal synthesis of the flower-like nanostructures is discussed.

Synthesis and Characterization of Polyaniline Microspheres Doped with Ferrocene Sulfonic Acid

2007 ◽  
Vol 121-123 ◽  
pp. 215-218
Author(s):  
Dan Ming Chao ◽  
J.Y. Chen ◽  
Xiao Feng Lu ◽  
Wan Jin Zhang
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Sulfonic Acid ◽  
Average Diameter ◽  
Ammonium Persulfate ◽  
Molar Ratio ◽  
Assembly Method ◽  
Transmission Electron ◽  
Backbone Structure

With an average diameter of 300-500 nm, conducting microspheres of polyaniline (PANI) were synthesized successfully by a self-assembly method in the presence of ferrocene sulfonic acid (FcSO3H) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) proved that the microspheres of PANI- FcSO3H synthesized by a self-assembly process were hollow ones. And the backbone structure of obtained PANI- FcSO3H was characterized by FTIR spectrum. The effect of synthetic conditions, such as the molar ratio of FcSO3H to aniline (An) and the reaction temperature, on the morphology and size was also investigated.

scholarly journals One-Step Synthesis of Silver Nanowires with Ultra-Long Length and Thin Diameter to Make Flexible Transparent Conductive Films

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 401 ◽  
Author(s):  
Yuxiu Li ◽  
Ximin Yuan ◽  
Hongwei Yang ◽  
Yunxiu Chao ◽  
Shuailong Guo ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Sheet Resistance ◽  
Silver Nanowires ◽  
Average Length ◽  
Synthesis Method ◽  
Average Diameter ◽  
Hydroxyethyl Cellulose ◽  
Molar Ratio ◽  
Conductive Film ◽  
One Step

High aspect ratio silver nanowires (AgNWs) with ultra-long length and thin diameter were synthesized through bromine ion (Br−)-assisted one-step synthesis method. The bromine ions were used as pivotal passivating agent. When the molar ratio of Br−/Cl− was 1:4, the average diameter of AgNWs was as low as ~40 nm, the average length was as high as ~120 μm, and the aspect ratio reached 2500. Networks of AgNWs were fabricated using as-prepared high-quality AgNWs as conducting material and hydroxyethyl cellulose (HEC) as the adhesive polymer. As a result, a low sheet resistance down to ~3.5 Ω sq−1 was achieved with a concomitant transmittance of 88.20% and a haze of 4.12%. The ultra-low sheet resistance of conductive film was attributed to the long and thin AgNWs being able to form a more effective network. The adhesion of the AgNWs to the substrate was 0/5B (ISO/ASTM). The insights given in this paper provide the key guidelines for bromine ion-assisted synthesis of long and thin AgNWs, and further designing low-resistance AgNW-based conductive film for optoelectronic devices.

Aspect Ratio Evaluation of Carbon Nanotubes Grown on Calcium Carbonate Substrate for Different Temperatures and Precursor Flow Times

2009 ◽  
Vol 4 ◽  
pp. 127-133 ◽  
Author(s):  
K.N. Pati ◽  
Chetan S. Solanki
Keyword(s):  
Carbon Nanotubes ◽  
Calcium Carbonate ◽  
Aspect Ratio ◽  
Average Diameter ◽  
Maximum Diameter ◽  
Analysis Software ◽  
Iron Cobalt ◽  
Average Aspect Ratio ◽  
Different Temperatures

Carbon Nanotubes (CNTs) are excellent material with a variety of physical, electrical, and mechanical properties. The average aspect ratio is evaluated for samples synthesized at different temperature and time of precursor flow. The experiments were conducted on calcium carbonate (CaCO3) substrate with iron-cobalt (Fe-Co) as a catalyst. Acetylene (C2H2) was used as a precursor gas and argon (Ar) as a carrier gas. The experiments were performed at temperatures ranging from 600 0C to 900 0C in step of 100 0C with time of precursor flow varying from 15 minutes to 75 minutes in the step of 15 minutes. The partial pressure of C2H2 and Ar kept constant during synthesis of CNT. The mass flow rate of C2H2 and Ar were 2 liters/hour and 60 liters/hour respectively during synthesis of CNT. The characterization of CNT was done with SEM, EDX, and TEM microscopes. Average aspect ratio of CNT is estimated using image analysis software. Most of nanotubes grown present an average diameter of 40 nm. The minimum and maximum diameter found are12.5 nm and 106 nm respectively. It is observed that average aspect ratio ranges from 25 to 58.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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