Atomic-Step-Induced Screw-Dislocation-Driven Spiral Growth of SnS

AbstractAgates with spectacular micro-structural features were found in volcanic rocks at several occurrences in the Saar-Nahe region (Germany). These agates include spirals of several tens up to several hundreds of μm in size within zones lacking the characteristic structural agate banding. A combined mineralogical study by polarising microscopy, scanning electron microscopy, cathodoluminescence microscopy and spectroscopy, and electron backscatter diffraction provided evidence that the spirals consist of well-ordered trigonal α-quartz, whereas the surrounding matrix is composed of strongly disordered or amorphous SiO2 phases. The quartz micro-crystals show a systematic rotation of the crystal orientation perpendicular to the direction of the spiral loops indicating helical growth.It is assumed that the spiral growth is initiated by dislocations with a screw component. The lacking symmetry of the strongly disordered or amorphous matrix initiated a curved development by a screw dislocation in a system far from equilibrium. The atoms/molecules are packed into spiral layers, which is energetically favoured in comparison with the incorporation into plane crystal faces. Such self-organisation growth and polymerisation initiated by a screw dislocation can produce variable spiral morphologies sometimes resembling living forms.

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Effect of Sulfur Evaporation Rate on Screw Dislocation Driven Growth of MoS2with High Atomic Step Density

Crystal Growth & Design ◽

10.1021/acs.cgd.6b01367 ◽

2016 ◽

Vol 16 (12) ◽

pp. 7145-7154 ◽

Cited By ~ 22

Author(s):

Pawan Kumar ◽

B. Viswanath

Keyword(s):

Screw Dislocation ◽

Evaporation Rate ◽

Atomic Step ◽

Step Density

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Screw-Dislocation-Driven Bidirectional Spiral Growth of Bi2Se3Nanoplates

Angewandte Chemie International Edition ◽

10.1002/anie.201403530 ◽

2014 ◽

Vol 53 (25) ◽

pp. 6425-6429 ◽

Cited By ~ 69

Author(s):

Awei Zhuang ◽

Jia-Jun Li ◽

You-Cheng Wang ◽

Xin Wen ◽

Yue Lin ◽

...

Keyword(s):

Screw Dislocation ◽

Spiral Growth

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Reduction of Threading Screw Dislocation Utilizing Defect Conversion during Solution Growth of 4H-SiC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.740-742.189 ◽

2013 ◽

Vol 740-742 ◽

pp. 189-192 ◽

Cited By ~ 17

Author(s):

S. Harada ◽

Yuji Yamamoto ◽

Kazuaki Seki ◽

Toru Ujihara

Keyword(s):

Screw Dislocation ◽

Seed Crystal ◽

Solution Growth ◽

Spiral Growth ◽

High Quality ◽

Special Shape ◽

Screw Dislocations ◽

Step Flow ◽

Polytype Transformation ◽

Step Flow Growth

Reduction of threading screw dislocation without polytype transformation from 4H-SiC was performed by the combination of step-flow growth and spiral growth. On a vicinal 4H-SiC seed crystal, threading screw dislocations are converted to Frank-type stacking faults by step-flow during solution growth. As the growth proceeds, the defects are excluded to the crystal. Thus utilizing the conversion, high quality SiC crystal growth without threading screw dislocations is expected to achieve. However, at the same time, polytype transformation is caused by the occurrence of 2D nucleation. By using the special shape of seed crystal, we successfully grew high quality 4H-SiC crystal without threading screw dislocation and polytype transformation.

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A New Defect in Polyethylene Single Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070795 ◽

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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