Oxygen-vacancy phase equilibria inYBa2Cu3Ozcalculated by the cluster variation method

1989 ◽  
Vol 39 (10) ◽  
pp. 6727-6736 ◽  
Author(s):  
A. Berera ◽  
D. de Fontaine
Keyword(s):  
Oxygen Vacancy ◽  
Phase Equilibria ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Cluster Variation

Theoretical Investigation of Alloy Phase Equilibria by Continuous Displacement Cluster Variation Method

2011 ◽  
Vol 172-174 ◽  
pp. 1119-1127
Author(s):  
Tetsuo Mohri
Keyword(s):  
Phase Equilibria ◽  
Lattice Point ◽  
Cluster Variation Method ◽  
Lattice Points ◽  
Variation Method ◽  
Bravais Lattice ◽  
Diffuse Intensity ◽  
Wide Range ◽  
Cluster Variation ◽  
Continuous Displacement

Continuous Displacement Cluster Variation Method is employed to study binary phase equilibria on the two dimensional square lattice with Lennard-Jones type pair potentials. It is confirmed that the transition temperature decreases significantly as compared with the one obtained by conventional Cluster Variation Method. This is ascribed to the distribution of atomic pairs in a wide range of atomic distance, which enables the system to attain the lower free energy. The spatial distribution of atomic species around a Bravais lattice point is visualized. Although the average position of an atom is centred at the Bravais lattice point, the maximum pair probability is not necessarily attained for the pairs located at the neighboring Bravais lattice points. In addition to the real space information, k-space information are calculated in the present study. Among them, the diffuse intensity spectra due to short range ordering and atomic displacement are discussed.

Application of Continuous Displacement Cluster Variation Method to Study Phase Equilibria

2010 ◽  
Vol 654-656 ◽  
pp. 1496-1499
Author(s):  
Tetsuo Mohri
Keyword(s):  
Transition Temperature ◽  
Phase Equilibria ◽  
Lattice Distortion ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Study Phase ◽  
Local Lattice Distortion ◽  
Local Lattice ◽  
Cluster Variation ◽  
Continuous Displacement

Cluster Variation Method (CVM) has been widely recognized as one of the most reliable theoretical tools to study phase equilibria in metallic alloy systems. The conventional CVM, however, does not allow atomic local displacements and, therefore, calculated results often encounter various inconveniences such as the overestimation of transition temperatures. Continuous Displacement Cluster Variation Method (CDCVM) was proposed to circumvent such deficiencies of the conventional CVM. Preliminary studies on an order-disorder phase diagram based on CDCVM indicate that the transition temperature is shifted downward reproducing experimental tendencies. In the present study, lattice thermal vibration effects are also incorporated through Morse potential. It is concluded that the local lattice distortion effects are quite effective to reduce the transition temperature.

Sign in / Sign up

Export Citation Format

Share Document