Four Directional Twinning Deformation of an Anisotropic Molecular Single Crystal Based on Three Different Modes of Mechanical Twinning

2021 ◽  
Author(s):  
Toshiyuki Sasaki ◽  
Shunichi Sakamoto ◽  
Satoshi Takamizawa
Keyword(s):  
Single Crystal ◽  
Mechanical Twinning

scholarly journals Crystallographic Structure of Polycrystalline Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 607-620 ◽  
Author(s):  
M. Matsuda ◽  
G. Wakahama
Keyword(s):  
Single Crystal ◽  
Great Majority ◽  
Mechanical Twinning ◽  
Boundary Structure ◽  
Crystallographic Structure ◽  
Oxygen Oxygen ◽  
Strong Shear ◽  
Polycrystalline Ice ◽  
Spatial Lattice ◽  
Glacier Ice

AbstractFor several types of polycrystalline ice of different origins, the spatial lattice orientation of each crystal was determined by measurements of both the a- and c-axis orientations. Analyses of the orientations of adjoining crystals showed that a great majority of adjoining crystals may be in a twinning relation. With special reference to the multi-maximum c-axis preferred-orientation fabric (the so-called “diamond pattern”), which is expected to occupy the largest part of a glacier ice mass, the crystal boundary structure was estimated. The preferred c-axis orientations of this fabric were explained as being the result of coincident oxygen-oxygen lines (hydrogen-bond lines) between adjoining crystals being concentrated in the orientations where seven oxygen-oxygen lines of one single crystal of ice are distributed. From the above result, it was concluded that the multi-maximum fabric is of the polycrystalline structure closest to the structure of a single crystal of ice among all the fabrics found in large ice masses.It is found that the occurrence, in glaciers and ice sheets, of a multi-maximum fabric has a bias to the parts which have undergone a strong shear deformation for a long time. It is thus suggested that plastic deformation of ice with this fabric may be attributed to mechanical twinning due to a strong shear stress.

Mechanical twinning in stoichiometric lithium niobate single crystal

1997 ◽  
Vol 180 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Bong Mo Park ◽  
Kenji Kitamura ◽  
Kazuya Terabe ◽  
Yasunori Furukawa ◽  
Yangyang Ji ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Single Crystal ◽  
Mechanical Twinning ◽  
Lithium Niobate Single Crystal

Crystallographic Structure of Polycrystalline Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 607-620 ◽  
Author(s):  
M. Matsuda ◽  
G. Wakahama
Keyword(s):  
Single Crystal ◽  
Great Majority ◽  
Mechanical Twinning ◽  
Boundary Structure ◽  
Crystallographic Structure ◽  
Oxygen Oxygen ◽  
Strong Shear ◽  
Polycrystalline Ice ◽  
Spatial Lattice ◽  
Glacier Ice

Abstract For several types of polycrystalline ice of different origins, the spatial lattice orientation of each crystal was determined by measurements of both the a- and c-axis orientations. Analyses of the orientations of adjoining crystals showed that a great majority of adjoining crystals may be in a twinning relation. With special reference to the multi-maximum c-axis preferred-orientation fabric (the so-called “diamond pattern”), which is expected to occupy the largest part of a glacier ice mass, the crystal boundary structure was estimated. The preferred c-axis orientations of this fabric were explained as being the result of coincident oxygen-oxygen lines (hydrogen-bond lines) between adjoining crystals being concentrated in the orientations where seven oxygen-oxygen lines of one single crystal of ice are distributed. From the above result, it was concluded that the multi-maximum fabric is of the polycrystalline structure closest to the structure of a single crystal of ice among all the fabrics found in large ice masses. It is found that the occurrence, in glaciers and ice sheets, of a multi-maximum fabric has a bias to the parts which have undergone a strong shear deformation for a long time. It is thus suggested that plastic deformation of ice with this fabric may be attributed to mechanical twinning due to a strong shear stress.

Structure Refinement Induced by Deformation Twinning in 77K Tensile Cu-8%at.Al Single Crystals

2011 ◽  
Vol 674 ◽  
pp. 61-69
Author(s):  
Małgorzata Perek-Nowak ◽  
Marek S. Szczerba
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Liquid Nitrogen ◽  
Structure Refinement ◽  
Deformation Twinning ◽  
Mechanical Twinning ◽  
Matrix Interface ◽  
Mode 2 ◽  
Interface Mode

In the paper the concept of structure refinement due to mechanical twinning is discussed. It is postulated that the process of structure refinement may occur when dominant crystal shear proceeds across twin-matrix interface (Mode 2). Contrary, if the crystal shear proceeds parallel to the interface (Mode 1) no condition for structure refinement is satisfied. The conditions of the structure refinement and no structure refinement are shown taking example of tensile Cu-8%at. Al single crystals of two orientations [1 4 5] and [1 1 2] tested in liquid nitrogen. The tensile characteristics are therefore divided into stages associated with the Mode 1 and Mode 2, which correspond to the fact whether refinement of single crystal structure is present or not, as it is proved by the EBSD analysis. The performed analysis showed that structure refinement consists of formation of regions of new orientations, where the most common feature is the II order twinning (the case [1 4 5]) supported by other regions of specific orientations necessary to accommodate mainly the transfer of crystal twin shear across the twin-matrix interface. Moreover, if the II order twinning plays the dominating function (the case [1 1 2]) higher order twins are to bring into operation to assure further ductility of a deformed sample.

Mechanical twinning in Ni-based single crystal superalloys during multiaxial creep at 1050 °C

2018 ◽  
Vol 722 ◽  
pp. 76-87 ◽  
Author(s):  
Jean-Briac le Graverend ◽  
Florence Pettinari-Sturmel ◽  
Jonathan Cormier ◽  
Muriel Hantcherli ◽  
Patrick Villechaise ◽  
...  
Keyword(s):  
Single Crystal ◽  
Mechanical Twinning ◽  
Multiaxial Creep

A Preparation of High Resolution Standards for Electron Microscopy. Part II

1971 ◽  
Vol 29 ◽  
pp. 160-161
Author(s):  
Akira Tanaka ◽  
David F. Harling
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Carbon Black ◽  
Single Crystal ◽  
Dark Field ◽  
Graphitized Carbon Black ◽  
Graphitized Carbon ◽  
Dark Field Imaging ◽  
Crystal Films ◽  
Micro Holes

In the previous paper, the author reported on a technique for preparing vapor-deposited single crystal films as high resolution standards for electron microscopy. The present paper is intended to describe the preparation of several high resolution standards for dark field microscopy and also to mention some results obtained from these studies. Three preparations were used initially: 1.) Graphitized carbon black, 2.) Epitaxially grown particles of different metals prepared by vapor deposition, and 3.) Particles grown epitaxially on the edge of micro-holes formed in a gold single crystal film.The authors successfully obtained dark field micrographs demonstrating the 3.4Å lattice spacing of graphitized carbon black and the Au single crystal (111) lattice of 2.35Å. The latter spacing is especially suitable for dark field imaging because of its preparation, as in 3.), above. After the deposited film of Au (001) orientation is prepared at 400°C the substrate temperature is raised, resulting in the formation of many square micro-holes caused by partial evaporation of the Au film.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Dislocations, Ordering and Antiferromagnetic Domains in MnO

1970 ◽  
Vol 28 ◽  
pp. 522-523
Author(s):  
D. J. Barber ◽  
R. G. Evans
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Optical Microscopy ◽  
Defect Chemistry ◽  
Magnetic Structures ◽  
Optically Transparent ◽  
Magnetic Features ◽  
Antiferromagnetic Domains

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.

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