Atomistic modeling of the vibrational and thermodynamic properties of uranium dioxide, UO2

Goel, Prabhatasree; Choudhury, N.; Chaplot, S. L.

doi:10.1016/j.jnucmat.2008.03.020

Cited by 32 publications

(27 citation statements)

References 50 publications

(84 reference statements)

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“…The reported studies have helped to formulate interatomic potential [5,26] to explain the vibrational properties of the oxides in concurrence with the available experimental data as in our previous works. The reported studies have helped to formulate interatomic potential [5,26] to explain the vibrational properties of the oxides in concurrence with the available experimental data as in our previous works.…”

Section: Introductionsupporting

confidence: 77%

Fast ion diffusion, superionic conductivity and phase transitions of the nuclear materials UO2 and Li2O

Goel

Choudhury

Chaplot

2009

Trans Indian Inst Met

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Uranium and lithium oxides are superionic conductors whose solid-state diffusion coefficients are comparable to that of liquids. They are also of technological importance to the nuclear industry. A detailed study of their physical and thermodynamic properties is of great interest for enhanced understanding of these systems. We review our lattice dynamics and molecular dynamics studies carried out on UO 2 and Li 2 O in their normal as well as superionic phase. Lattice dynamic calculations have been carried out using shell model in the quasiharmonic approximation. The calculated elastic constants, phonon frequencies and specific heat are in good agreement with the reported experimental data. Lattice dynamics calculations of the thermodynamic properties help validate the interatomic potentials required for undertaking molecular dynamics simulations to study the diffusion behavior in UO 2 and Li 2 O. The diffusion constant of Li in Li 2 O and O in UO 2 have been determined and compared with the experiment. The calculated superionic transition temperature of Li 2 O is 1000 K while that of UO 2 is 2300 K. With the help of molecular dynamics simulations the microscopic picture of the local structure of the lattice just beyond the transition temperature has been deduced. The structural behavior of UO 2 and Li 2 O, have also been simulated at high pressure. UO 2 is found to undergo a sluggish transformation to a high-pressure cotunnite phase at about 40 GPa. Similarly Li 2 O reveals an anti-fluorite to anti-cotunnite transformation (as reported in angle dispersive X-ray studies) at about 50 GPa. Our lattice dynamical calculations show up similar transformations for UO 2 and Li 2 O at 70 and 25 GPa respectively.

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Section: Introductionsupporting

confidence: 77%

Fast ion diffusion, superionic conductivity and phase transitions of the nuclear materials UO2 and Li2O

Goel

Choudhury

Chaplot

2009

Trans Indian Inst Met

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“…As in our previous works [1,28], molecular dynamics simulations were carried out in the rigid ions approximation for the 10 sets of empirical pair potentials: Walker-81 [29], Busker-02 [30], Nekrasov-08 [22], Goel-08 [31], obtained in the harmonic approximation from elastic properties at zero temperature; Morelon-03 [18], obtained using the lattice statics from energy of Frenkel and Schottky defects; Yamada-00 [16], Basak-03 [17], Arima-05 [32], MOX-07 [33] and Yakub-09 [34], obtained using MD simulation of thermal expansion and bulk modulus. Parameters of all these SPPs are given in Tables 1-3 of the first article [1].…”

Section: Methodsmentioning

confidence: 99%

High-precision molecular dynamics simulation of UO2–PuO2: Anion self-diffusion in UO2

Potashnikov

Boyarchenkov

Nekrasov

et al. 2013

Journal of Nuclear Materials

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h i g h l i g h t s" We perform MD simulation of oxygen diffusion in UO2 (up to 50 000 ions and 1 ls time)." We reached 1400 K and 10 À12 cm 2 /sec, which allowed direct comparison to experiments." S-shaped T-dependence of activation energy and k-peak of its derivative were obtained. " Continual superionic phase transition (rather than first or second order) was proved. t r a c tOur series of articles is devoted to high-precision molecular dynamics simulation of mixed actinide-oxide (MOX) fuel in the approximation of rigid ions and pair interactions (RIPI) using high-performance graphics processors (GPU). In this article we study self-diffusion mechanisms of oxygen anions in uranium dioxide (UO 2 ) with the 10 recent and widely used sets of interatomic pair potentials (SPP) under periodic (PBC) and isolated (IBC) boundary conditions. Wide range of measured diffusion coefficients (from 10 À3 cm 2 /s at melting point down to 10 À12 cm 2 /s at 1400 K) made possible a direct comparison (without extrapolation) of the simulation results with the experimental data, which have been known only at low temperatures (T < 1500 K). A highly detailed (with the temperature step of 1 K) calculation of the diffusion coefficient allowed us to plot temperature dependences of the diffusion activation energy and its derivative, both of which show a wide ($1000 K) superionic transition region confirming the broad k-peaks of heat capacity obtained by us earlier. It is shown that regardless of SPP the anion self-diffusion in model crystals without surface or artificially embedded defects goes on via exchange mechanism, rather than interstitial or vacancy mechanisms suggested by the previous works. The activation energy of exchange diffusion turned out to coincide with the anti-Frenkel defect formation energy calculated by the lattice statics.

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“…During last years, a large amount of experimental [1][2][3][4][5] as well as theoretical studies using either atomistic models [6][7][8][9][10][11][12][13][14][15][16][17][18][19] or micro-mechanical ones [20,21] were carried out in order to better understand the physical properties of bulk UO 2 and its macroscopic property evolution under irradiation.…”

Section: Introductionmentioning

confidence: 99%

An atomistic modelling of the porosity impact on UO2 matrix macroscopic properties

Jelea

Colbert

Ribeiro

et al. 2011

Journal of Nuclear Materials

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Atomistic modeling of the vibrational and thermodynamic properties of uranium dioxide, UO2

Cited by 32 publications

References 50 publications

Fast ion diffusion, superionic conductivity and phase transitions of the nuclear materials UO2 and Li2O

Fast ion diffusion, superionic conductivity and phase transitions of the nuclear materials UO2 and Li2O

High-precision molecular dynamics simulation of UO2–PuO2: Anion self-diffusion in UO2

An atomistic modelling of the porosity impact on UO2 matrix macroscopic properties

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