Thermal conductivities of americium dioxide and sesquioxide by molecular dynamics simulations

Uchida, Teppei; Arima, Takahiro; Idemitsu, Kazuya; Inagaki, Yoshiyuki

doi:10.1016/j.commatsci.2008.09.012

Cited by 15 publications

(10 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, Uchida et al calculated the thermal conductivity of AmO 2 , AmO 1.5 and sub-stoichiometric AmO 2Àx using molecular dynamics [9,10]. However, no experimental data exist at high temperature for the thermal conductivities of AmO 2 and AmO 1.5 except at 333 K due to the difficulty in keeping stoichiometric composition at high temperature.…”

Section: Introductionmentioning

confidence: 98%

Heat capacities and thermal conductivities of AmO2 and AmO1.5

Nishi

Itoh

Ichise

et al. 2011

Journal of Nuclear Materials

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 98%

Heat capacities and thermal conductivities of AmO2 and AmO1.5

Nishi

Itoh

Ichise

et al. 2011

Journal of Nuclear Materials

View full text Add to dashboard Cite

“…In order to calculate the thermal conductivity of non-stoichiometric americium oxide, we needed the potential parameters for both Am 4+ -O 2À and Am 3+ -O 2À systems. In the previous study [15], these potential parameters were determined to reproduce lattice structures, thermal expansions and bulk moduli experimentally obtained for fluorite AmO 2 and cubic bixbyite Am 2 O 3 crystals [1,2,[5][6][7][19][20][21]. Potential parameters summarized in Table 1 were adequate for AmO 2 , however these gave a little small bulk modulus of Am 2 O 3 .…”

Section: Interatomic Potential Function and Non-equilibrium Molecularmentioning

confidence: 99%

“…(1), z i is the effective charge of a type i ion, and an ionic bonding of 67.5% is assumed for each ion in the present simulated system [12][13][14][15]17,18]. In order to calculate the thermal conductivity of non-stoichiometric americium oxide, we needed the potential parameters for both Am 4+ -O 2À and Am 3+ -O 2À systems.…”

Section: Interatomic Potential Function and Non-equilibrium Molecularmentioning

confidence: 99%

See 1 more Smart Citation

Thermal conductivity of non-stoichiometric americium oxide: A molecular dynamics study

Uchida

Arima

Idemitsu

et al. 2010

Journal of Nuclear Materials

Self Cite

View full text Add to dashboard Cite

a b s t r a c tThe aim of this paper is to investigate the influence of multi-valency of americium in its oxide for the lowering of the thermal conductivity and the uncertainty in measurement. In the present study, thermal conductivity of non-stoichiometric americium oxide was evaluated up to 2000 K by the non-equilibrium molecular dynamics calculations using the Born-Mayer-Huggins interatomic potential with the partially ionic model. The oxygen-to-americium ratio (O/Am) was varied from 1.6 to 1.9, which corresponded to the variation of the ratio of Am 3+ /Am 4+ . So, we prepared potential parameters for both Am 3+ and Am 4+ . The calculated thermal conductivity of non-stoichiometric americium oxide decreased with an increase of temperature, and the degree of the temperature dependence became smaller with a decrease of the O/Am ratio. This was mainly caused by the phonon-scattering due to oxygen vacancies induced with Am 3+ ions. Comparing two supercells in which (1) short-range ordered Am 3+ clusters were contained and (2) Am 3+ ions were randomly distributed, the thermal conductivity of the former seemed to be somewhat larger than that of the latter.

show abstract

“…These potential parameters for the oxygen ion were given by Inaba 20) and the parameters for actinide ions were determined by our previous studies. 18,21) In this study, the GB structures of Σ41, Σ13, Σ5 and Σ29 were explored. These GB structures were constructed based on the coincidence-site-lattice (CSL) theory for the fluorite crystal structure, 22) and have misorientation angles of 12.7°, 22.6°, 36.9° and 46.4°, respectively.…”

Section: Simulation Methodsmentioning

confidence: 99%

Molecular Dynamics Study on Grain Boundary Diffusion of Actinides and Oxygen in Oxide Fuels

Nishina

Yoshida

Arima

et al. 2011

Progress in Nuclear Science and Technology

Self Cite

View full text Add to dashboard Cite

Diffusion phenomena of actinides and oxygen are relating to various properties of oxide fuels, e.g. actinide and oxygen redistribution, pore migration, sintering behavior. Although lots of experimental data have been obtained for U and O diffusions, these seem to be a little scattered among experiments. In addition, there are few studies of transuranium elements. Recently, we experimentally showed that diffusion coefficients of Am and Pu were almost comparable with that of U and the contribution of grain boundaries (GB) were relatively large in oxide fuels. On the other hand, the molecular dynamics (MD) calculation showed that U ions migrated via its vacancies and the O diffusion mechanism changed with temperature in bulk. In this study, the GB diffusion coefficients and the mechanism were systematically evaluated for U, Am and O in oxide fuels by MD calculations. For actinides and oxygen, their GB diffusion coefficients are significantly larger than bulk ones, and the diffusion mechanisms in GBs are almost independent on temperature. Furthermore, the GB diffusion is strongly dependent on its structure and the interfacial potential energy. The lower oxygen-to-metal (O/M) ratio gives the larger GB diffusion coefficients for actinides and oxygen.

show abstract

Thermal conductivities of americium dioxide and sesquioxide by molecular dynamics simulations

Cited by 15 publications

References 21 publications

Heat capacities and thermal conductivities of AmO2 and AmO1.5

Heat capacities and thermal conductivities of AmO2 and AmO1.5

Thermal conductivity of non-stoichiometric americium oxide: A molecular dynamics study

Molecular Dynamics Study on Grain Boundary Diffusion of Actinides and Oxygen in Oxide Fuels

Contact Info

Product

Resources

About