Dependence between calculated flexibility of lamellas of layered materials and their ability to undergo intercalation reactions

1991 ◽  
Vol 56 (12) ◽  
pp. 2859-2868 ◽  
Author(s):  
Jiří Votinský ◽  
Ludvík Beneš
Keyword(s):  
Computational Procedure ◽  
Layered Materials ◽  
Space Group

A computational procedure has been suggested enabling estimates of the flexibility of individual layered materials from their crystallographical structure. The data about flexibility of layers have been obtained by calculation for compounds of the type Q2Y3 (Q = SbIII, BiIII; Y = Se-II, Te-II; space group of symmetry R3m), MPS3 (M = MnII, FeII, CoII, NiII, CdII,C2/m), TX2 (T = NbIV, TaIV, MoV; X = S-II, Se-II; P63/mmc), FeOCl (Pmnm), Zr(HPO4)2 (P21/n) and ROPO4 (R = VV, NbV, Mo; P4/n). The flexibility of the layers of these compounds increases in the order: Q2Y3 << MPS3 < TX2 < FeOCl = Zr(HPO4)2 < ROPO4. The same trend is observed for the ability of these compounds to form intercalates. In most of the structures given a distinct anisotropy of flexibility has been found by the calculation.

New Quaternary Selenoantimonates AHgSbSe3 (A = Rb, Cs): Synthesis, Structures and Optical Properties

1998 ◽  
Vol 547 ◽  
Author(s):  
Zhen Chen ◽  
Ru-Ji Wang ◽  
Jing Li
Keyword(s):  
Optical Properties ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Diffuse Reflectance ◽  
Layered Materials ◽  
Band Gaps ◽  
Alkali Metal Cations ◽  
Monoclinic System ◽  
Orthorhombic System ◽  
Space Group

AbstractSolvothermal reactions in ethylenediamine have resulted in two quaternary mercury containing selenoantimonates: RbHgSbSe3 (I) and CsHgSbSe3 (II). Compound I crystallizes in monoclinic system, space group P2l/c (no. 14) with a = 7.758(2)Å, b = 11.234(2)Å, c = 8.849(2) Å, β = 106.60(3)°, V = 739.1(3)Å3, Z = 4. Compound II crystallizes in orthorhombic system, space group Cmcm (no. 63) with a = 4.444(1)Å, b = 15.514(6)Å, c = 11.261(7) Å, V = 776.4(6) Å3, Z = 4. Both compounds are layered materials and their crystal structures are closely related. Both contain layers of 2[HgSbSe3-] separated by alkali-metal cations A+ (Rb, Cs). Diffuse reflectance experiments show that both compounds are semiconductors with estimated band gaps of 1.7 eV for I and 1.6 eV for II, respectively.

High Resolution Electron Microscopy of internal interfaces in layered materials

1990 ◽  
Vol 48 (4) ◽  
pp. 320-321
Author(s):  
Yoichi Ishida ◽  
Hideki Ichinose ◽  
Yutaka Takahashi ◽  
Jin-yeh Wang
Keyword(s):  
Grain Boundaries ◽  
Mirror Symmetry ◽  
Functional Materials ◽  
High Resolution Electron Microscopy ◽  
Layered Materials ◽  
Plane Boundary ◽  
Chemical Information ◽  
Layer Plane ◽  
High Tc ◽  
Cubic Metals

Layered materials draw attention in recent years in response to the world-wide drive to discover new functional materials. High-Tc superconducting oxide is one example. Internal interfaces in such layered materials differ significantly from those of cubic metals. They are often parallel to the layer of the neighboring crystals in sintered samples(layer plane boundary), while periodically ordered interfaces with the two neighboring crystals in mirror symmetry to each other are relatively rare. Consequently, the atomistic features of the interface differ significantly from those of cubic metals. In this paper grain boundaries in sintered high-Tc superconducting oxides, joined interfaces between engineering ceramics with metals, and polytype interfaces in vapor-deposited bicrystal are examined to collect atomic information of the interfaces in layered materials. The analysis proved that they are not neccessarily more complicated than that of simple grain boundaries in cubic metals. The interfaces are majorly layer plane type which is parallel to the compound layer. Secondly, chemical information is often available, which helps the interpretation of the interface atomic structure.

Multislice calculations for quasi-periodic and non-periodic objects

1990 ◽  
Vol 48 (4) ◽  
pp. 138-139
Author(s):  
R. Herrera ◽  
A. Gómez
Keyword(s):  
Electron Diffraction ◽  
Computer Simulations ◽  
Periodic Table ◽  
Amorphous Materials ◽  
Space Group ◽  
Essential Step ◽  
Shape Effects ◽  
Atomic Scattering ◽  
Diffraction Patterns ◽  
Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

An HREM study of superstructures in Ca4Al6SO16

1990 ◽  
Vol 48 (4) ◽  
pp. 1066-1067
Author(s):  
Y.G. Wang ◽  
H.Q. Ye ◽  
K.H. Kuo
Keyword(s):  
Calcium Aluminate ◽  
Structural Model ◽  
Bright Spot ◽  
Sulphur Atom ◽  
Synthetic Compound ◽  
Space Group ◽  
Lattice Images ◽  
Cubic Structure ◽  
Good Agreement

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).

Misfit Dislocations in the Ilmenite (FeTiO3)-Hematite (Fe2O3) System

1980 ◽  
Vol 38 ◽  
pp. 212-213 ◽  
Author(s):  
K.P.D. Lagerlöf ◽  
A.H. Heuer ◽  
T.E. Mitchell
Keyword(s):  
Misfit Dislocation ◽  
Lattice Parameters ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Space Group ◽  
Two Phases ◽  
Hematite Fe2o3

It has been reported by Lally et. al. [1] that precipitates of hematite (Fe2O3, space group R3c) in a matrix of ilmenite (FeTiO3, space group R3) are lens shaped and flattened along the [0001]-direction. The coherency across the interface is lost by the introduction of a misfit dislocation network, which minimizes the strain due to the deviation in lattice parameters between the two phases [2]. The purpose of this paper is to present a new analysis of this network.

Space group of bis(biguanidinium)nickel(II) fluoride tetrahydrate

1971 ◽  
Vol 133 (133) ◽  
pp. 491-492
Author(s):  
J. Belgaumkar ◽  
B. K. Samantaray
Keyword(s):  
Space Group

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

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