First principles investigation of thermal transport of uranium mononitride

Szpunar, Barbara; Ranasinghe, Jayangani I.; Malakkal, Linu; Szpunar, Jerzy A.

doi:10.1016/j.jpcs.2020.109636

Cited by 23 publications

(11 citation statements)

References 31 publications

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“…We assumed 5f 3 , 6d 1 , 7s 2 for U and 2s 2 , 2p 3 for N as the electronic configurations. The evaluated lattice constants for non-magnetic UN (0.489 nm) and using this setup [5] agreed very well with the experimental value of 0.489 [14].…”

Section: Resultssupporting

confidence: 82%

“…Here we adopted for UN the same parameters and norm-conserving pseudopotentials: U.pbesol-n-nc.UPF and N.pbesol-nc.UPF from QE code as in our previous studies [5]. We assumed 5f 3 , 6d 1 , 7s 2 for U and 2s 2 , 2p 3 for N as the electronic configurations.…”

Section: Resultsmentioning

confidence: 99%

“…A very accurate evaluation of the electronic structure was required; therefore, in addition to generalized gradient approximation (GGA) of the Perdew, Burke, and Ernzerhof functional developed for solids (PBEsol) [11] DFT, we used non-local Becke three-parameter hybrid exchange (B3)+LYP functional (B3LYP) [8] to modify the electronic structure around Fermi energy, and the respective electronic heat coefficients were compared. We used the same norm-conserved pseudopotentials and setup for the electronic structure calculations as detailed in our previous work on UN [5].…”

Section: Calculation Methodologymentioning

confidence: 99%

“…Using the density functional perturbation theory (DFPT) method as implemented in QE code [12], we evaluated previously [5] the phonons' dispersion relation and the densities of states of UN.…”

Section: Calculation Methodologymentioning

confidence: 99%

“…In our previous papers [4] [5], we have investigated UN, which has the same cubic structure ( 3 Fm m symmetry) as ThN, and may be used in combination to enhance thermal conductivity as both are metals. In these metallic fuels, thermal conductivity does not deteriorate with increasing temperature like the lattice-governed thermal conductivity in insulators (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Electronic Transport of Uranium Mononitride

Szpunar¹,

Ranasinghe²,

Szpunar³

2021

JMP

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We investigated the electronic heat capacity, thermal conductivity, and resistivity of UN using Quantum Espresso and EPW code. GGA, PBEsol functional was used. The calculated electronic heat coefficient was found to be significantly reduced (0.0176 J•mol −1 •K −2 versus 0.0006 J•mol −1 •K −2 ) when the non-local hybrid functional (B3LYP) was used. Furthermore, we calculated electrical resistivity using a very transparent Ziman's formula for metals with the Eliashberg transport coupling function as implemented in EPW code for non-spin-polarized calculations. The number of mobile electrons in UN, as a function of temperature, was derived from the ratio of the calculated resistivity and available experimental data. The electronic thermal conductivity was evaluated from the calculated electronic resistivity via Wiedemann-Franz law with the number of mobility electrons (n av ) incorporated (averaged over the temperature range 300 K -1000 K). Both the electronic thermal conductivity and resistivity, as calculated using newly evaluated n av , compare well with experimental data at ~700 K, but to reproduce the observed trend as a function of temperature, the number of mobile electrons must decrease with the temperature as evaluated.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%