Anisotropic Growth of Otavite on Calcite: Implications for Heteroepitaxial Growth Mechanisms

2017 ◽  
Vol 18 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Shawn L. Riechers ◽  
Sebastien N. Kerisit
Keyword(s):  
Anisotropic Growth ◽  
Growth Mechanisms ◽  
Heteroepitaxial Growth

Study of Initial Stages of Heteroepitaxy Using Graded Thickness Samples

1987 ◽  
Vol 102 ◽  
Author(s):  
D. K. Biegelsen ◽  
F. A. Ponce ◽  
B. S. Krusor ◽  
J. C. Tramontana ◽  
R. D. Yingling
Keyword(s):  
Clean Surface ◽  
Growth Mechanisms ◽  
Heteroepitaxial Growth ◽  
Continuous Evolution ◽  
Gaas On Si ◽  
Sample Deposition ◽  
Graded Thickness ◽  
Nucleation Growth

ABSTRACTIn this paper we introduce the technique of graded thickness sample deposition to study the heteroepitaxial growth mechanisms of GaAs on Si. We can observe the continuous evolution from the initial clean surface, through nucleation, growth and coalescence of the deposited material.

Anisotropic Growth of Cubic PbTe Nanoparticles to Nanosheets: Controlled Synthesis and Growth Mechanisms

2010 ◽  
Vol 10 (8) ◽  
pp. 3727-3731 ◽  
Author(s):  
T. J. Zhu ◽  
X. Chen ◽  
X. Y. Meng ◽  
X. B. Zhao ◽  
J. He
Keyword(s):  
Controlled Synthesis ◽  
Anisotropic Growth ◽  
Growth Mechanisms

Element-specific anisotropic growth of shaped platinum alloy nanocrystals

Science ◽  
2014 ◽  
Vol 346 (6216) ◽  
pp. 1502-1506 ◽  
Author(s):  
Lin Gan ◽  
Chunhua Cui ◽  
Marc Heggen ◽  
Fabio Dionigi ◽  
Stefan Rudi ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Chemical Degradation ◽  
Anisotropic Growth ◽  
Growth Mechanisms ◽  
Platinum Alloy ◽  
Alloy Nanocrystals ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Compositional Patterns ◽  
Alloy Catalysts

Morphological shape in chemistry and biology owes its existence to anisotropic growth and is closely coupled to distinct functionality. Although much is known about the principal growth mechanisms of monometallic shaped nanocrystals, the anisotropic growth of shaped alloy nanocrystals is still poorly understood. Using aberration-corrected scanning transmission electron microscopy, we reveal an element-specific anisotropic growth mechanism of platinum (Pt) bimetallic nano-octahedra where compositional anisotropy couples to geometric anisotropy. A Pt-rich phase evolves into precursor nanohexapods, followed by a slower step-induced deposition of an M-rich (M = Ni, Co, etc.) phase at the concave hexapod surface forming the octahedral facets. Our finding explains earlier reports on unusual compositional segregations and chemical degradation pathways of bimetallic polyhedral catalysts and may aid rational synthesis of shaped alloy catalysts with desired compositional patterns and properties.

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.

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

1989 ◽  
Vol 47 ◽  
pp. 592-593
Author(s):  
J.B. Posthill ◽  
R.P. Burns ◽  
R.A. Rudder ◽  
Y.H. Lee ◽  
R.J. Markunas ◽  
...  
Keyword(s):  
Thin Films ◽  
Wide Band ◽  
Deposition Process ◽  
Heteroepitaxial Growth ◽  
Electron Microscopic ◽  
Wide Band Gap ◽  
Lattice Matching ◽  
Different Types ◽  
Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Financial Systems and economic Development in the Russian Regions: A Comparative Analysis

2015 ◽  
pp. 94-108 ◽  
Author(s):  
K. Krinichansky
Keyword(s):  
Economic Development ◽  
Comparative Analysis ◽  
Financial Development ◽  
Public Debt ◽  
Fixed Capital ◽  
Russian Regions ◽  
Growth Mechanisms ◽  
Financial Systems ◽  
Debt Market ◽  
Regions Of Russia

The paper identifies and assesses the closeness of the connection between incremental indicators of the financial development in the regions of Russia with the incremental regional GDP and the investment in fixed capital. It is shown that the positioning of the region as an independent participant of public debt market matters: the regional GDP and investment in fixed capital grow more rapidly in the regions which are regularly borrowing on the sub-federal bonds market. The paper also demonstrates that the poorly developed financial system in some regions have caused the imperfection of the growth mechanisms since the economy is not able to use the financial system’s functions.

Chemical and Electrochemical Heteroepitaxial Growth of Chalcogenide Semiconductors from Solutions

1996 ◽  
Vol 451 ◽  
Author(s):  
D. Lincot ◽  
M. J. Furlong ◽  
M. Froment ◽  
R. Cortes ◽  
M. C. Bernard
Keyword(s):  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
Basic Principles ◽  
Lattice Match ◽  
X Ray ◽  
Chalcogenide Semiconductors ◽  
Influence Of Temperature On ◽  
Deposition Processes ◽  
A Site ◽  
Site Selective

ABSTRACTChalcogenide semiconductors have been deposited epitaxially from aqueous solutions either chemically or electrochemically at growth rates of up to 0.7 μmhr−1. After recalling the basic principles of these deposition processes, results are presented concerning chemically deposited CdS on InP, GaP and CuInSe2 substrates, electrodeposited CdTe on InP, and CdSAnP heterostructures. Characterisation of these structures by RHEED, TEM, HRTEM, and glazing angle X ray diffraction allows to analyse the effects of substrate orientation, polarity, lattice match plus the influence of temperature on epitaxial growth. These results are discussed in terms of self organisation and a site selective growth mechanisms due to the free enegy of formation of each compound.

Morphologies and Growth Mechanisms of the Eutectic Particles in As-Cast Al-Mg-Sc Alloy

2017 ◽  
Vol 54 (4) ◽  
pp. 241-255
Author(s):  
D. Pan ◽  
S. Zhou ◽  
Z. Zhang ◽  
M. Li ◽  
H. Li ◽  
...  
Keyword(s):  
Growth Mechanisms ◽  
Eutectic Particles
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