A bonding parameter. II, Rock salt and cesium chloride crystal structures

1969 ◽  
Vol 46 (1) ◽  
pp. 28 ◽  
Author(s):  
Jesse Elson
Keyword(s):  
Crystal Structures ◽  
Rock Salt ◽  
Cesium Chloride ◽  
Chloride Crystal ◽  
Bonding Parameter

Structural Properties of CaS1-xSex Mixed Crystal under High Pressure

2014 ◽  
Vol 1047 ◽  
pp. 51-59
Author(s):  
Anita Singh ◽  
Ekta Sharma ◽  
Umesh Kumar Sakalle
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Properties ◽  
Rock Salt ◽  
Cesium Chloride ◽  
Relative Volume ◽  
Transition Pressure ◽  
Phase Transition Pressure ◽  
Volume Collapse ◽  
Vegard’S Law

The mixed ionic crystals are formed by the mixing of pure components and are truly crystalline and their lattice constants change linearly with concentration from one pure member to another. The present work is intended to investigate structural properties of CaS1-xSexunder high pressure. The structural properties of mixed compound CaS1-xSex(0≤x≤1) under high pressures have been evaluated using three body potential model (TBPM). This interaction potential has been calculated by using three model parameters. For this mixed compound, the experimental data has been generated by the application of Vegard’s law to experimental values available for pure end-point members.The Structure of CaS and CaSe has been Rock Salt (B1) at ambient pressure and with increasing pressure Rock Salt (B1) structure undergo a transition in Cesium Chloride (B2) at 40GPa and 38 GPa respectively and CaS1-xSexunder goes Rock Salt to Cesium Chloride (B1→B2) structure. The difference in phase transition pressure in end-point members is low. In the present work we have investigated structural properties at high pressure for five different concentration x (x=0, 0.25, 0.50, 0.75, 1) for CaS1-xSex. Phase transition pressure and relative volume collapse at different phase transition pressure for different values of x has been calculated. Predicted phase transition pressure and relative volume collapse are found in good agreement with experimental and other theoretical data. Linear variation of phase transition pressure and lattice constant of different composition show that Vegard’s law is valid for this alloy. We have evaluated the phase transition pressure from graphical analysis where the Gibb’s free energy difference ΔG [G(B1)-G(B2)] have been plotted against pressure (P) for CaS1-xSexfor different concentration x. The pressure at which ΔG approaches zero corresponds to phase –transition pressure (Pt). The relative volume changes, ΔV(Pt)/V(0), associated with the above mentioned compression have also been computed and plotted against pressure to get the phase diagram for CaS1-xSexin different concentration.

Universal-binding-energy relations across the rock-salt–cesium chloride phase transition in alkali halides

1997 ◽  
Vol 56 (6) ◽  
pp. 3010-3015 ◽  
Author(s):  
A. Martín Pendás ◽  
J. M. Recio ◽  
E. Francisco ◽  
V. Luaña
Keyword(s):  
Phase Transition ◽  
Binding Energy ◽  
Rock Salt ◽  
Alkali Halides ◽  
Cesium Chloride ◽  
Energy Relations

SPECIFIC HEATS AND DISPERSION CURVES FOR CsCl ON THE BASIS OF THE SHELL MODEL

1967 ◽  
Vol 45 (10) ◽  
pp. 3339-3346 ◽  
Author(s):  
G. P. Srivastava ◽  
B. Dayal
Keyword(s):  
Specific Heat ◽  
Shell Model ◽  
Lattice Dynamics ◽  
Cesium Chloride ◽  
Dispersion Curves ◽  
Experimental Results ◽  
Fair Agreement ◽  
Chloride Crystal ◽  
Specific Heats ◽  
Positive Ions

The shell model of Dick and Overhauser as developed by Cochran and Woods el al. has been applied to study theoretically the lattice dynamics of a cesium chloride crystal. The polarizabilities of both negative and positive ions have been taken into account in this treatment. The charges on the shells of the two ions come out to be of different magnitude. It is seen that the theoretical specific-heat variation with temperature based on this model is in fair agreement with experimental results in the range for which they have been obtained. The theoretical dispersion curves in the three symmetry directions are also given.

Crystal Phases of Glass-Forming Mixtures

2002 ◽  
Vol 754 ◽  
Author(s):  
Julián R. Fernández ◽  
Peter Harrowell
Keyword(s):  
Crystal Structures ◽  
Finite Size ◽  
Amorphous State ◽  
Cesium Chloride ◽  
Layered Crystal ◽  
Face Centered Cubic ◽  
Glass Forming ◽  
Equimolar Composition ◽  
Face Centered ◽  
Ordered State

ABSTRACTWe compare the potential energy at zero temperature of a range of crystal structures for a glass-forming binary mixture of Lennard-Jones particles. The lowest energy ordered state consists of coexisting phases of a single component face centered cubic structure and an equimolar cesium chloride structure. An infinite number of layered crystal structures are identified with energies close to this groundstate. We demonstrate that the finite size increase of the energy of the coexisting crystal with incoherent interfaces is sufficient to destabilize this ordered phase in simulations of typical size. Specific local coordination structures are identified as of possible structural significance in the amorphous state. We observe rapid crystal growth in mixtures near the equimolar composition.

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

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