Morphology Control of Cryptomelane Type MnO2Nanowires by Soft Chemistry. Growth Mechanisms in Aqueous Medium

2007 ◽  
Vol 19 (22) ◽  
pp. 5410-5417 ◽  
Author(s):  
David Portehault ◽  
Sophie Cassaignon ◽  
Emmanuel Baudrin ◽  
Jean-Pierre Jolivet
Keyword(s):  
Aqueous Medium ◽  
Morphology Control ◽  
Growth Mechanisms ◽  
Soft Chemistry

Synthesis of nanometric TiO2 in aqueous solution by soft chemistry: obtaining of anatase, brookite and rutile with controlled shapes

2004 ◽  
Vol 822 ◽  
Author(s):  
Magali Koelsch ◽  
Sophie Cassaignon ◽  
Jean-Pierre Jolivet
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Medium ◽  
Crystalline Structure ◽  
Soft Chemistry ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Nanometric Particles ◽  
Size And Morphology ◽  
Hcl Medium

AbstractNanometric particles of titania, exhibiting anatase, brookite or rutile polymorphs, were synthesized by thermohydrolysis of TiCl4 in aqueous medium. The adjustement of physico-chemical parameters (acidity, ionic strength, anions, temperature) allows to tune the crystalline structure, the size and the morphology of the particles. Brookite results from the precipitation of titanium in HCl, HBr or HNO3 whereas anatase is formed in H2SO4 medium. Adding salts in HCl medium leads to ionic strength or complexation effect. Varying the temperature of thermohydrolysis implies modification on yield, size and morphology of the particles.

Mono and Tri-cationic Imidazolium Salts: Use as Stabilizers for Silver Nanoparticles and Anticancer Study

2021 ◽  
Vol 6 (3) ◽  
pp. 167-174
Author(s):  
R. Rohini ◽  
N. Naresh Reddy ◽  
A. Sanjeev ◽  
S. Bhaskar ◽  
P. Muralidhar Reddy
Keyword(s):  
Silver Nanoparticles ◽  
Aqueous Medium ◽  
Chemical Reduction ◽  
Reaction Medium ◽  
Morphology Control ◽  
Medium Effect ◽  
Imidazolium Salts ◽  
Size And Morphology ◽  
Size And Morphology Control

In present strudy, the synthesis and characterization of monocationic 1,3-tetradecylimidazolium; [(C14)2Im]Br and tricationic benzene centered tris-tetradecyl/hexadecyl imidazolium bromide salts; i.e. [(C14)3C6H3Im]Br3 and [(C16)3C6H3ImBr]Br3 is reported. The stabilizer role of imidazolium salts to prepare silver nanoparticles (AgNPs) via chemical reduction method was investigated. To understand the reaction medium effect on the size and morphology control of AgNPs, monophasic (aqueous medium) and biphasic (DCM/H2O) approaches were applied. The morphology control was noticed for AgNPs protected with [(C14)3C6H3Im]Br3 (show sphere like morphology) and [(C14)2Im]Br (show dendritic structures) via biphasic approach. A clear variation in the size and morphology of AgNPs was noticed by varying the type of stabilizers and reaction medium. It was also observed that AgNPs were formed and stabilized only in aqueous medium in both approaches, thus it is assumed that AgNPs surfaces were protected by imidazolium salts with bilayer fashion. Anticancer activity of imidazolium salts was performed by MTT assay against HeLa cancer cell lines. The result shows that cytotoxic activity of tricationic [(C14)3C6H3Im]Br3 was more potent than that of monocationic [(C14)2Im]Br. The outcome suggests that there is an urgent need to develop new polycationic imidazolium salts for various chemical and medicinal applications.

Morphology control of nickel oxalate by soft chemistry and conversion to nickel oxide for application in photocatalysis

RSC Advances ◽  
2013 ◽  
Vol 3 (17) ◽  
pp. 6106 ◽  
Author(s):  
Soumyadipta Rakshit ◽  
Sayantani Chall ◽  
Soumya Sundar Mati ◽  
Anirban Roychowdhury ◽  
S.P. Moulik ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Morphology Control ◽  
Soft Chemistry ◽  
Nickel Oxalate

Growth mechanisms, morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium

2009 ◽  
Vol 159 (5-6) ◽  
pp. 406-414 ◽  
Author(s):  
Emanuela Tamburri ◽  
Silvia Orlanducci ◽  
Francesco Toschi ◽  
Maria Letizia Terranova ◽  
Daniele Passeri
Keyword(s):  
Aqueous Medium ◽  
Growth Mechanisms

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

Crystal structure images of large gold clusters and growing crystals by HRTEM

1984 ◽  
Vol 42 ◽  
pp. 428-429
Author(s):  
L.R. Wallenberg ◽  
J.-O. Bovin ◽  
G. Schmid
Keyword(s):  
Crystal Structure ◽  
Nucleation And Growth ◽  
Close Packing ◽  
Gold Clusters ◽  
Molecular Weight Determination ◽  
Growth Mechanisms ◽  
Starting Point ◽  
Different Types ◽  
Nucleation And Growth Mechanisms ◽  
Points Of View

Metallic clusters are interesting from various points of view, e.g. as a mean of spreading expensive catalysts on a support, or following heterogeneous and homogeneous catalytic events. It is also possible to study nucleation and growth mechanisms for crystals with the cluster as known starting point.Gold-clusters containing 55 atoms were manufactured by reducing (C6H5)3PAuCl with B2H6 in benzene. The chemical composition was found to be Au9.2[P(C6H5)3]2Cl. Molecular-weight determination by means of an ultracentrifuge gave the formula Au55[P(C6H5)3]Cl6 A model was proposed from Mössbauer spectra by Schmid et al. with cubic close-packing of the 55 gold atoms in a cubeoctahedron as shown in Fig 1. The cluster is almost completely isolated from the surroundings by the twelve triphenylphosphane groups situated in each corner, and the chlorine atoms on the centre of the 3x3 square surfaces. This gives four groups of gold atoms, depending on the different types of surrounding.

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

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