Chemical Structure and Crystal Size in Polymer Single Crystals

1969 ◽  
Vol 2 (1) ◽  
pp. 98-103 ◽  
Author(s):  
H. K. Livingston
Keyword(s):  
Single Crystals ◽  
Chemical Structure ◽  
Crystal Size

Silicate ionic liquid synthesis of zeolite merlinoite: Crystal size control from crystalline nanoaggregates to micron-sized single-crystals

2014 ◽  
Vol 198 ◽  
pp. 35-44 ◽  
Author(s):  
Mohamed Haouas ◽  
Louwanda Lakiss ◽  
Charlotte Martineau ◽  
Jaafar El Fallah ◽  
Valentin Valtchev ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Single Crystals ◽  
Crystal Size ◽  
Size Control

Preparation and Characterization of Wurtzitic Gan Single Crystals in Nano and Micro Scale

1996 ◽  
Vol 423 ◽  
Author(s):  
San Yu ◽  
Hongdong Li ◽  
Haibin Yang ◽  
Dongmei Li ◽  
Haiping Sun ◽  
...  
Keyword(s):  
Single Crystals ◽  
Crystal Size ◽  
Arc Discharge ◽  
Short Wave ◽  
Wurtzite Structure ◽  
Light Emitters ◽  
X Ray ◽  
Lattice Constants ◽  
Micro Scale ◽  
Transmission Electron

AbstractGallium nitride and its alloys are the most promising materials for short wave light emitters. If high quality GaN single crystals can be prepared, the GaN base light emitters should be fabricated directly on the lattice-matched GaN substrate.In this work, GaN crystals in nano and micro scale with definite faces have been prepared by dc arc discharge using gallium and N2+NH3 as starting materials. Transmission electron microscope, selected area diffraction, x-ray microanalysis of energy dispersive spectroscopy, and x-ray diffraction investigation of the as grown GaN crystals show that the well faceted crystals are single crystalline GaN in wurtzite structure having lattice constants a0=3.18Å and c0=5.18Å. The crystal size of stoichoimetric GaN in wurtzite structure depends on the partial pressure of nitrogen in the plasma. The maximum crystal size in this work is about several micrometers.

Influence of chemical structure on enzymatic degradation of single crystals of PCL-b-PEO amphiphilic block copolymer

Polymer ◽  
2010 ◽  
Vol 51 (11) ◽  
pp. 2426-2434 ◽  
Author(s):  
Ni Jiang ◽  
Shidong Jiang ◽  
Yi Hou ◽  
Shouke Yan ◽  
Guangzhao Zhang ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Single Crystals ◽  
Chemical Structure ◽  
Enzymatic Degradation ◽  
Amphiphilic Block Copolymer

Ionic additive strategy to control nucleation and generate larger single crystals of 3D covalent organic frameworks

2021 ◽  
Author(s):  
Xiaohan Wang ◽  
Riku Enomoto ◽  
Yoichi Murakami
Keyword(s):  
Single Crystals ◽  
Crystal Size ◽  
Covalent Organic Frameworks ◽  
Ionic Additive

To generate large single crystals of 3D covalent organic frameworks, the active use of ionic additives, which can greatly impact crystal size, is proposed. The crystal size ranking was found...

The burning and explosion of single crystals

1957 ◽  
Vol 238 (1214) ◽  
pp. 325-333 ◽  
Keyword(s):  
Single Crystals ◽  
High Speed ◽  
Crystal Size ◽  
Initial Temperature ◽  
Silver Azide ◽  
Break Up

A study has been made of the combustion and explosion of single crystals of a number of compounds. These include the styphnates, fulminates and azides. A high-speed ciné microscope developed by Courtney-Pratt has been used. This enables magnified pictures of events lasting several milliseconds to be recorded. Crystals which have faults break up during combustion, and particles fly off at high speed. When the crystals are relatively free from faults the combustion may be followed along the length of the crystal and burning speeds may be measured. A variation in speed with crystal size and initial temperature has been observed, and this is discussed in relation to thermal losses during burning. The combustion of cyanuric triazide under water has also been recorded. The behaviour of the compounds such as silver and thallous azide which can melt is different from that of crystals which explode without melting. The effect of crystal size on the development of combustion and explosion is discussed with particular reference to silver azide.

scholarly journals Effects of crystal size on methanol to hydrocarbon conversion over single crystals of ZSM-5 studied by synchrotron infrared microspectroscopy

2020 ◽  
Vol 22 (34) ◽  
pp. 18849-18859
Author(s):  
Ivalina B. Minova ◽  
Santhosh K. Matam ◽  
Alex Greenaway ◽  
C. Richard A. Catlow ◽  
Mark D. Frogley ◽  
...  
Keyword(s):  
Induction Period ◽  
Single Crystals ◽  
Crystal Size ◽  
Hydrocarbon Conversion ◽  
Infrared Microspectroscopy ◽  
Hydrocarbon Pool ◽  
Methanol To Hydrocarbon ◽  
Increasing Temperature

The induction period for alkene formation from methanol in single crystals of HZSM-5 decreases with decreasing crystal size and increasing temperature and hydrocarbon pool species are formed almost instantaneously at higher temperatures.

Synthesis of [Ca2(Co1-xCux)2O4] yCoO2 Single Crystals and Their Intrinsic Properties

2002 ◽  
Vol 755 ◽  
Author(s):  
M. Suzuki ◽  
S. Horii ◽  
M. Sano ◽  
K. Fujie ◽  
K. Otzschi ◽  
...  
Keyword(s):  
Single Crystals ◽  
Crystal Size ◽  
Present System ◽  
Intrinsic Properties ◽  
Flux Method ◽  
Solid Solution Range ◽  
High Seebeck Coefficient ◽  
Irreversible Magnetization ◽  
Magnetization Behavior ◽  
Anisotropic Magnetization

ABSTRACTThin plate-like [Ca2(Co1-xCux)2O4] y CoO2 single crystals were successfully grown by the flux method using SrCl2 solvent. The largest crystal size was approximately 3 × 3 × 0.01 mm3. The copper concentrations, x, in the crystals were found to be depending on each crystal, suggesting a certain solid-solution range of copper in the present system. The obtained crystal showed low resistivity (∼4.3mQcm) and high Seebeck coefficient (∼160μVK-1) at 300K. The crystal showed anisotropic magnetization with larger magnetization under H ∥ c. Irreversible magnetization behavior below ∼90K was also found under H ∥ c.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

Inelastic Electron-Matter Interactions

1978 ◽  
Vol 36 (3) ◽  
pp. 259-267
Author(s):  
J. Silcox
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Chemical Structure ◽  
Inelastic Electron ◽  
Primary Concern ◽  
Unique Probe ◽  
Introductory Paper ◽  
Elastic Processes ◽  
Experimental Level ◽  
Inelastic Processes

In this introductory paper, my primary concern will be in identifying and outlining the various types of inelastic processes resulting from the interaction of electrons with matter. Elastic processes are understood reasonably well at the present experimental level and can be regarded as giving information on spatial arrangements. We need not consider them here. Inelastic processes do contain information of considerable value which reflect the electronic and chemical structure of the sample. In combination with the spatial resolution of the electron microscope, a unique probe of materials is finally emerging (Hillier 1943, Watanabe 1955, Castaing and Henri 1962, Crewe 1966, Wittry, Ferrier and Cosslett 1969, Isaacson and Johnson 1975, Egerton, Rossouw and Whelan 1976, Kokubo and Iwatsuki 1976, Colliex, Cosslett, Leapman and Trebbia 1977). We first review some scattering terminology by way of background and to identify some of the more interesting and significant features of energy loss electrons and then go on to discuss examples of studies of the type of phenomena encountered. Finally we will comment on some of the experimental factors encountered.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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