scholarly journals Stacking Sequence, Interlayer Bonding, Termination Group Stability and Li/Na/Mg Diffusion in MXenes

2021 ◽  
pp. 1369-1376
Author(s):  
Jacob Hadler-Jacobsen ◽  
Frode Håskjold Fagerli ◽  
Henning Kaland ◽  
Sondre Kvalvåg Schnell
Keyword(s):  
Stacking Sequence ◽  
Group Stability ◽  
Interlayer Bonding

scholarly journals Anorpiment, As2S3, the triclinic dimorph of orpiment

2011 ◽  
Vol 75 (6) ◽  
pp. 2857-2867 ◽  
Author(s):  
A. R. Kampf ◽  
R. T. Downs ◽  
R. M. Housley ◽  
R. A. Jenkins ◽  
J. Hyršl
Keyword(s):  
New Mineral ◽  
Stacking Sequence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Greenish Yellow ◽  
Covalently Bonded ◽  
Mohs Hardness ◽  
Interlayer Bonding ◽  
Hydrothermal Mineral

AbstractThe new mineral anorpiment, As2S3, the triclinic dimorph of orpiment, has space group PI and cell parameters a = 5.7577(2), b = 8.7169(3), c = 10.2682(7) Å, α = 78.152(7), β = 75.817(7), γ = 89.861(6)°, V = 488.38(4) Å3 and Z = 4. It occurs at the Palomo mine, Castrovirreyna Province. Huancavelica Department, Peru. It is a low-temperature hydrothermal mineral associated with dufrenoysite, muscovite, orpiment, pyrite and realgar. It occurs in drusy crusts of wedge-shaped, transparent, greenish yellow crystals. The streak is yellow. The lustre is resinous on crystal faces, but pearly on cleavage surfaces. The Mohs hardness is about VA. The mineral is sectile with an irregular fracture and one perfect and easy cleavage on ﹛001﹜. The measured and calculated densities are 3.33 and 3.321 g cm–3, respectively. All indices of refraction are greater than 2. The mineral is optically biaxial (—) with 2V = 35—40° and no observed dispersion. The acute bisectrix (X) is approximately perpendicular to the ﹛001﹜ cleavage. Electron microprobe analyses yielded the averages and ranges in wt.%: As 58.21 (57.74–59.03), S 38.72 (38.33–39.00), total 96.94 (96.07–97.75), providing the empirical formula (based on 5 atoms) As1.96S3.04. The strongest powder X-ray diffraction lines are [d (hkl) I] 4.867(002) 97, 4.519 (110,11̄1) 77, 3.702 (1̄1̄1) 46, 3.609 (022,11̄2) 82, 2.880(201,02̄2,1̄2̄1,023) 75, 2.552 (1̄13,1̄31,132) 100, 2.469 (114,130,13̄1) 96. The structure of anorpiment [R1 = 0.021 for 1484 reflections with F0 > 4σ(F)] consists of layers of covalently bonded As and S atoms. Each S atom bonds to two As atoms at As—S—As angles between 100.45 and 104.15°. Each As atom is strongly bonded to three S atoms at S—As—S angles between 91.28 and 103.59°, forming an AsS3 pyramid with As at its apex. The As—S linkages within the layers form rings of six AsS3 pyramids. Interlayer bonding forces are interpreted as van der Waals. The structure of anorpiment is similar to that of orpiment in that it is composed of layers of As2S3 macromolecules, but arranged in a different stacking sequence.

High Resolution Study of Polytypism: Application to SiC and Au3 Mn

1982 ◽  
Vol 40 ◽  
pp. 540-541
Author(s):  
G. Van Tendeloo ◽  
J. Van Landuyt ◽  
S. Amelinckx
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Stacking Sequence ◽  
X Ray ◽  
Powerful Technique ◽  
Resolution Study ◽  
The Ideal

Polytypism has been studied for a number of years and a wide variety of stacking sequences has been detected and analysed. SiC is the prototype material in this respect; see e.g. Electron microscopy under high resolution conditions when combined with x-ray measurements is a very powerful technique to elucidate the correct stacking sequence or to study polytype transformations and deviations from the ideal stacking sequence.

Defect structures of Nb1+αS2 sulfidation scales

1992 ◽  
Vol 50 (1) ◽  
pp. 38-39
Author(s):  
Chuxin Zhou ◽  
L. W. Hobbs
Keyword(s):  
Stacking Faults ◽  
Rhombohedral Structure ◽  
Stacking Sequence ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Normal ◽  
Lower Case ◽  
Sulfur Layer ◽  
Two Phases

One of the major purposes in the present work is to study the high temperature sulfidation properties of Nb in severe sulfidizing environments. Kinetically, the sulfidation rate of Nb is satisfactorily slow, but the microstructures and non-stoichiometry of Nb1+αS2 challenge conventional oxidation/sulfidation theory and defect models of non-stoichiometric compounds. This challenge reflects our limited knowledge of the dependence of kinetics and atomic migration processes in solid state materials on their defect structures.Figure 1 shows a high resolution image of a platelet from the middle portion of the Nb1+αS2 scale. A thin lamellar heterogeneity (about 5nm) is observed. From X-ray diffraction results, we have shown that Nb1+αS2 scale is principally rhombohedral structure, but 2H-NbS2 can result locally due to stacking faults, because the only difference between these 2H and 3R phases is variation in the stacking sequence along the c axis. Following an ABC notation, we use capital letters A, B and C to represent the sulfur layer, and lower case letters a, b and c to refer to Nb layers. For example, the stacking sequence of 2H phase is AbACbCA, which is a ∼12Å period along the c axis; the stacking sequence of 3R phase is AbABcBCaCA to form an ∼18Å period along the c axis. Intergrowth of these two phases can take place at stacking faults or by a shear in the basal plane normal to the c axis.

Stacking Sequence Dispersion for Improved Damage Tolerance

2008 ◽  
Author(s):  
Claudio Lopes ◽  
Pedro Camanho ◽  
Zafer Gurdal ◽  
Omprakash Seresta ◽  
Pere Maimi
Keyword(s):  
Damage Tolerance ◽  
Stacking Sequence

scholarly journals Enhanced Impact Properties of Hybrid Composites Reinforced by Carbon Fiber and Polyimide Fiber

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2599
Author(s):  
Boyao Wang ◽  
Bin He ◽  
Zhanwen Wang ◽  
Shengli Qi ◽  
Daijun Zhang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Failure Modes ◽  
Flexural Modulus ◽  
Charpy Impact ◽  
Fiber Reinforced Composites ◽  
Stacking Sequence ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Polyimide Fiber

A series of hybrid fiber-reinforced composites were prepared with polyimide fiber and carbon fiber as the reinforcement and epoxy resin as the matrix. The influence of stacking sequence on the Charpy impact and flexural properties of the composites as well as the failure modes were studied. The results showed that hybrid fiber-reinforced composites yielded nearly 50% increment in Charpy impact strength compared with the ones reinforced by carbon fiber. The flexural performance was significantly improved compared with those reinforced solely by polyimide fibers and was greatly affected by the stacking sequence. The specimens with compressive sides distributed with carbon fiber possessed higher flexural strength, while those holding a sandwich-like structure with carbon fiber filling between the outer layers displayed a higher flexural modulus.

scholarly journals First-Principles Study of a MoS2-PbS van der Waals Heterostructure Inspired by Naturally Occurring Merelaniite

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1649
Author(s):  
Gemechis D. Degaga ◽  
Sumandeep Kaur ◽  
Ravindra Pandey ◽  
John A. Jaszczak
Keyword(s):  
Density Functional ◽  
Van Der Waals ◽  
Hole Mobility ◽  
Functional Theory ◽  
Mos2 Monolayer ◽  
Naturally Occurring ◽  
Weak Interlayer ◽  
Bulk Structure ◽  
P Type ◽  
Interlayer Bonding

Vertically stacked, layered van der Waals (vdW) heterostructures offer the possibility to design materials, within a range of chemistries and structures, to possess tailored properties. Inspired by the naturally occurring mineral merelaniite, this paper studies a vdW heterostructure composed of a MoS2 monolayer and a PbS bilayer, using density functional theory. A commensurate 2D heterostructure film and the corresponding 3D periodic bulk structure are compared. The results find such a heterostructure to be stable and possess p-type semiconducting characteristics. Due to the heterostructure’s weak interlayer bonding, its carrier mobility is essentially governed by the constituent layers; the hole mobility is governed by the PbS bilayer, whereas the electron mobility is governed by the MoS2 monolayer. Furthermore, we estimate the hole mobility to be relatively high (~106 cm2V−1s−1), which can be useful for ultra-fast devices at the nanoscale.

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