Paper 6.1

Statistical thermodynamics of binary systems with variable valent states (mixed valence) of ions for one of components. Application for the uranium-oxygen system

 

Zakharov A.Yu.1, Zakharov M.A.1, Udovsky A.L.2,1, Oonk H.3

 

1Department of Theoretical and Mathematical Physics, Yaroslav Vise Novgorod State Univetsity

Petebyrgskaya street, 41, Great Novgorod, Russia

2  Baikov Institute of Metallurgy and Materials Science, Russian Academy od Sciences

Leninsky Prospect, 49, Moscow 119991, Russia

3Chemical Department of the Utrecht University, Padualaan 8,

NL-3584 CH Utrecht, The Netherlands

 

The aim of the investigations was to developed of the statistical thermodynamics of binary systems with variable valent states (mixed valence) of ions for one of components, in particular for description thermodynamic properties different phases of the uranium – oxygen system including the UO2+-x-base solid solutions. This report contain following:

 

1. Short-range parts of the interatomic potentials and the geometric constraints method. The dense packing principle for condensed (both liquid and solid) multicomponent systems.

 

2. Long-range part of the interatomic potentials and mean field approximation. The configuration part of Helmholtz free energy.

 

3. The free energy functional and its conditional extremum. The equilibrium conditions.

 

4. Vacancies as one of the components in the system. The thermodynamic variables renormalization.

 

5. Integral equations for the equilibrium distributions of components, their asymptotic properties, and some limiting cases.

 

6. Multiatomic complexes in condensed systems and their manifestations in thermodynamic functions.

 

7. Equilibrium between several complexes and compounds with variable valence.

 

8. Structural statistical model for the UO2+-x-base solid solutions as mixture differed multiatomic complexes with variable valent uranium ions and structural  vacancies

 

The work was partially supported by Scientific Program "Universities of Russia" (Project No. UR.01.01.024), Russian Federal Program "Integration" (Project No. B0056), and Russian-Dutch Program RFBR-NWO (Project 047.011.2001.011).

 

E-mail: ayz@novsu.ac.ru