Twinning and crystal slip in black monoclinic ZnP2

1986 ◽  
Vol 1 (1) ◽  
pp. 187-192 ◽  
Author(s):  
Michael E. Fleet ◽  
Joseph C. White
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Slip Plane ◽  
Cell Parameter ◽  
Twin Plane ◽  
Stacking Fault ◽  
Orthorhombic Unit Cell ◽  
Partial Dislocations ◽  
Parameter Ratio ◽  
Monoclinic Cell

Monoclinic βZnP2 (black ZnP2) single crystals, synthesized in the presence of excess P, contain regions of polysynthetic lamellar-twinned structure, with dislocations and stacking fault-like features. The twin law is a* twin axis, (100) composition plane: (100) is also the slip plane. The twin composition plane migrates across (100) lattice fringes. In the revised βZnP2 crystal structure, Zn(1) and P(4) positions are related across a (100) twin composition plane at x = 0.84 by two twin operations, with axes through is also a possible slip plane, with three partial dislocations, ½[001], ½[001], and ½[001]. A third possible twin operation relates Zn(2) and P(1) positions across a (100) twin plane at x = 0.5, with twin axis through All twin and slip operations result in very little distortion in nearest- and nextnearest-neighbor coordination geometries. Twin and stacking fault mistakes may be facilitated by approach of the monoclinic cell parameter ratio c[α sin(β — π/2)] to 4 (which yields a pseudo-orthorhombic unit cell) and by Zn1-xP2 nonstoichiometry.

scholarly journals Twinning in Czochralski-Grown 36°-RY LiTaO3 Single Crystals

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1009
Author(s):  
Yutaka Ohno ◽  
Yuta Kubouchi ◽  
Hideto Yoshida ◽  
Toshio Kochiya ◽  
Tomio Kajigaya
Keyword(s):  
Single Crystals ◽  
Slip Plane ◽  
Edge Dislocation ◽  
Lithium Tantalate ◽  
Initiation Site ◽  
The Other ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Dislocation Arrays ◽  
Extension Direction

The origin of twinning during the Czochralski (CZ) growth of 36°-RY lithium tantalate (LiTaO3) single crystals is examined, and it is shown that lineages composed of dislocation arrays act as an initiation site for twinning. Two types of lineages expand roughly along three different {12¯10} planes and two different {11¯00} planes. The former lineages and some latter lineages are composed of two types of mixed-dislocations with different Burgers vectors, while the other lineages are composed of only one type of edge-dislocation. All the dislocations have the Burgers vector of ⟨12¯10⟩ type with the compression side at the +Z side. Twin lamellae on {101¯2} are generated at a lineage during the CZ growth. We have hypothesized that dislocations in the lineage with b = 1/3⟨12¯10⟩ change their extension direction along a slip plane of {101¯2}, and they dissociate into pairs of partial dislocations with b = 1/6⟨22¯01⟩and 1/6⟨02¯21¯⟩ forming twin lamellae on {101¯2}.

The role of structural imperfections in the photodimerization of 9-cyanoanthracene

1971 ◽  
Vol 324 (1559) ◽  
pp. 459-468 ◽  
Keyword(s):  
Fluorescence Microscopy ◽  
Excitation Energy ◽  
Slip Plane ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Structural Imperfections ◽  
Active Slip

Crystalline 9-cyanoanthracene undergoes photodimerization to give the trans dimer which is unexpected on the basis of the topochemical preformation theory. The possibility that the reaction occurs at defects is investigated; and the nature of the structural imperfections are described, as are also the types of product nuclei and their modes of growth. Interference-contrast and fluorescence microscopy have been employed for the examination of cleaved and partially dimerized faces of the monomer. It is shown that there is an active slip plane (221), and consideration of feasible dislocation reactions, particularly those involving unit strength dislocations which have a component of the Burgers vector in [100], reveals that, within stacking-fault regions (bounded by partial dislocations), the monomer molecules are in trans registry. It is suggested that molecules in such stacking faults act as traps for the excitation energy, and that reaction occurs at these sites.

Syntheses, Single-crystal Structure and Vibrational Spectra of Ca15(CBN)6(C2)2H2

2011 ◽  
Vol 66 (11) ◽  
pp. 1092-1096
Author(s):  
Olaf Reckeweg ◽  
Armin Schulz ◽  
Francis J. DiSalvoa
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Title Compound ◽  
Cell Parameter ◽  
Single Crystal Structure ◽  
Boron Powder ◽  
Space Group ◽  
Ir And Raman

Single crystals of Ca15(CBN)6(C2)2H2 were obtained either by the reaction of stoichiometric amounts of graphite, hexagonal BN, and CaH2 with an excess of distilled Ca, or by using graphite, boron powder, Ca3N2, and CaH2 with an excess of distilled Ca. Both reactions took place in silicajacketed Ta ampoules at 1400 K. Crystals of the title compound are transparent dark-red and isopointal to Ca15(CBN)6(C2)2O adopting the cubic space group Ia3̄d (no. 230, Z = 8) with the cell parameter a = 1653.30(17) pm. The vibrational spectra were recorded and are compared with IR and Raman data of isotypic compounds

scholarly journals Кристаллическая структура и ширина запрещенной зоны твердых растворов (MnIn-=SUB=-2-=/SUB=-S-=SUB=-4-=/SUB=-)-=SUB=-1-x-=/SUB=-·(AgIn-=SUB=-5-=/SUB=-S-=SUB=-8-=/SUB=-)-=SUB=-x-=/SUB=-

2018 ◽  
Vol 52 (8) ◽  
pp. 958
Author(s):  
И.В. Боднарь ◽  
Чан Бинь Тхан
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Single Crystals ◽  
Absorption Edge ◽  
Entire Range ◽  
Spinel Structure ◽  
Cell Parameter ◽  
Fundamental Absorption Edge ◽  
Composition Parameter ◽  
First Time

AbstractThe (MnIn_2S_4)_1– x • (AgIn_5S_8)_ x alloy single crystals are grown for the first time by the Bridgman method in the entire range of component concentrations. The composition of the single crystals and their crystal structure are determined. It is shown that the alloy crystallizes in the cubic spinel structure. The unit-cell parameter of the single crystals ( a ) is calculated, and its dependence on the composition parameter ( x ) is determined. It is established that the parameter a linearly varies with x . From the transmittance spectra in the region of the fundamental absorption edge, the band gap ( E _ g ) of the MnIn_2S_4 and AgIn_5S_8 compounds and (MnIn_2S_4)_1– x • (AgIn_5S_8)_ x alloys is determined, and the dependence of Eg on the parameter x is constructed. It is found that the band gap E _ g nonlinearly varies with x and has a maximum at x = 0.6.

scholarly journals Comparison of the temperature- and pressure-dependent behavior of the crystal structure of CrAs

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Andreas Eich ◽  
Andrzej Grzechnik ◽  
Carsten Paulmann ◽  
Thomas Müller ◽  
Yixi Su ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressures ◽  
Cell Parameter ◽  
Anomalous Behavior ◽  
Superconducting Properties ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Parameter Ratio ◽  
Dependent Behavior ◽  
Temperature And Pressure

The crystal structure of CrAs was investigated using synchrotron X-ray single-crystal diffraction for separate dependences on temperature (30–400 K) and on pressure (0–9.46 GPa). The isosymmetrical magnetostructural phase transition at T N = 267 K can induce a change in the microstructure by twinning due to a crossing of the orthohexagonal setting of the unit-cell parameter ratio c/b. Within the crystal structure, one particular Cr–Cr distance exhibits anomalous behavior in that it is nearly unaffected by temperature and pressure in the paramagnetic phase, which is stable above 267 K and at high pressures. The distinction of this shortest Cr–Cr distance might be of importance for the superconducting properties of CrAs.

Über ein neues Kupfervanadat: Cu4V2.15O 9.38 / About Cu4V2,15O9.38

1975 ◽  
Vol 30 (3-4) ◽  
pp. 175-178 ◽  
Author(s):  
H.-P. Christian ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Hydrothermal Synthesis ◽  
Single Crystals ◽  
Unit Cell ◽  
The Other ◽  
Structure Investigation ◽  
Orthorhombic Unit Cell ◽  
Space Group ◽  
Group D

Single crystals of Cu4V2.15O9,38 were prepared by hydrothermal synthesis. The composition was confirmed by analysis and crystal structure investigation. Cu4V2.15O9,38 has an orthorhombic unit cell : a = 15.021, b = 8.564 and c = 6.055 Å, space group D24P 212121. The structure consists of a network made up of chains of edge-shared Cu-O6 octahedra. The chains are linked by Cu-O6 octahedra building up a wave-like layer parallel to the b/c plane. The layers are linked to each other by V—O4 tetrahedra and two sorts of trigonal bipyramids one of them containing copper. The center of the other one is statistically filled with vanadium.

scholarly journals Die Kristallstruktur des α-Na2S5 / The Crystal Structure of α-Na2S5

1984 ◽  
Vol 39 (5) ◽  
pp. 577-581 ◽  
Author(s):  
P. Böttcher ◽  
R. Keller
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystals ◽  
Solid State Reaction ◽  
Unit Cell ◽  
Melting Reaction ◽  
Orthorhombic Unit Cell ◽  
X Ray ◽  
In Cis ◽  
Excess Sulfur

Na2S5 has been Synthesized from β-Na2S2 and excess sulfur by a two step reaction. A solid state reaction at 200 °C was carried out, which was then followed by a melting reaction at 500 °C. X-ray investigations on single crystals revealed the structure of the α-modification. The orthorhombic unit cell contains four formula units; the space group is Pnma. The sulfur atoms form unbranched zig-zag-chains S52- in cis-conformation

OnemoreCompound Containing the CBN4- Ion – Synthesis, Single-crystal Structure and Vibrational Spectra of Ca15(CBN)6(C2)2F2

2010 ◽  
Vol 65 (12) ◽  
pp. 1409-1415 ◽  
Author(s):  
Olaf Reckeweg ◽  
Armin Schulz ◽  
Francis J. Di Salvo
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Title Compound ◽  
Cell Parameter ◽  
Single Crystal Structure ◽  
Space Group ◽  
Ir And Raman

Single crystals of Ca15(CBN)6(C2)2F2 were obtained by the reaction of graphite, hexagonal BN and CaF2 with an excess of distilled Ca metal in silica-jacketed Ta ampoules at 1300 K. The title compound is transparent red and crystallizes isopointal to Ca15(CBN)6(C2)2O adopting the cubic space group Ia 3̄d (no. 230, Z = 8) with the cell parameter a = 1653.6(4) pm. Its vibrational spectra are compared with IR and Raman data of similar compounds from the literature and with the newly measured Raman spectra of Ca5(BC2)(C2)Cl3 and Ca9(BC2)2Cl8.

Grain Subdivision During Deformation Studied by Automatic EBSP

1999 ◽  
Vol 5 (S2) ◽  
pp. 232-233
Author(s):  
D. Juul Jensen
Keyword(s):  
Plastic Deformation ◽  
Single Crystals ◽  
Slip Plane ◽  
Cell Formation ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
General Description ◽  
Length Scales ◽  
Dislocation Walls

During plastic deformation of typical metals the original grains subdivide. Subdivision by cell formation is a well-known phenomena in metals with medium to high stacking fault energy, but the subdivision may also take place on larger length scales by: i) Formation of single-walled dense dislocation walls (DDWs) and/or double-walled microbands (MBs). The DDWs/MBs are seen as elongated, nearly straight, vertically parallel dislocation boundaries which delineate several cells, thus bounding cell blocks. Typical examples are shown in Fig. 1. ii) Subdivision on a grain scale, for example due to grain-grain interactions or due to the formation of transition bands separating matrix bands. This subdivision is typical for both single crystals and polycrystals. For a general description and recent overview, see [1, 2].The grain subdivision depends on the orientation of the grains. The morphology may appear different in grains of different orientations and the DDW/MBs can be parallel or inclined to a slip plane.

On effects of non-systematic reflections on weak-beam images of partial dislocations

1991 ◽  
Vol 49 ◽  
pp. 688-689
Author(s):  
K. Z. Botros ◽  
S. S. Sheinin
Keyword(s):  
High Precision ◽  
Stacking Fault ◽  
Important Application ◽  
Stacking Fault Energy ◽  
Sharp Peak ◽  
Weak Beam ◽  
Partial Dislocations ◽  
Deviation Parameter ◽  
Beam Diffraction

The main features of weak beam images of dislocations were first described by Cockayne et al. using calculations of intensity profiles based on the kinematical and two beam dynamical theories. The feature of weak beam images which is of particular interest in this investigation is that intensity profiles exhibit a sharp peak located at a position very close to the position of the dislocation in the crystal. This property of weak beam images of dislocations has an important application in the determination of stacking fault energy of crystals. This can easily be done since the separation of the partial dislocations bounding a stacking fault ribbon can be measured with high precision, assuming of course that the weak beam relationship between the positions of the image and the dislocation is valid. In order to carry out measurements such as these in practice the specimen must be tilted to "good" weak beam diffraction conditions, which implies utilizing high values of the deviation parameter Sg.

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