The contribution of nitrogen Frenkel-pair formation to the high-temperature heat capacity of uranium mononitride
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arXiv
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| Natura: | Preprint |
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2026
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| _version_ | 1866911540211351552 |
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| author | AbdulHameed, Mohamed Beeler, Benjamin |
| author_facet | AbdulHameed, Mohamed Beeler, Benjamin |
| contents | The high-temperature heat capacity of uranium mononitride (UN) remains uncertain due to conflicting measurements and models above ~1700 K. To assess whether intrinsic defect formation contributes to the observed superlinear behavior of $C_P(T)$, we perform large-scale molecular dynamics simulations using two interatomic potentials to quantify nitrogen diffusion and Frenkel-pair populations from 1800--2600 K. Both models show increasing anion mobility, but the Tseplyaev potential yields substantially larger Frenkel concentrations, producing a defect heat-capacity contribution of up to ~10 J/(mol-K). This defect-driven term is consistent with the curvature seen in historical correlations and recent ab initio results, suggesting that nitrogen sublattice disorder provides a plausible intrinsic mechanism for the high-temperature heat capacity of UN. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_02441 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | The contribution of nitrogen Frenkel-pair formation to the high-temperature heat capacity of uranium mononitride AbdulHameed, Mohamed Beeler, Benjamin Materials Science The high-temperature heat capacity of uranium mononitride (UN) remains uncertain due to conflicting measurements and models above ~1700 K. To assess whether intrinsic defect formation contributes to the observed superlinear behavior of $C_P(T)$, we perform large-scale molecular dynamics simulations using two interatomic potentials to quantify nitrogen diffusion and Frenkel-pair populations from 1800--2600 K. Both models show increasing anion mobility, but the Tseplyaev potential yields substantially larger Frenkel concentrations, producing a defect heat-capacity contribution of up to ~10 J/(mol-K). This defect-driven term is consistent with the curvature seen in historical correlations and recent ab initio results, suggesting that nitrogen sublattice disorder provides a plausible intrinsic mechanism for the high-temperature heat capacity of UN. |
| title | The contribution of nitrogen Frenkel-pair formation to the high-temperature heat capacity of uranium mononitride |
| topic | Materials Science |
| url | https://arxiv.org/abs/2603.02441 |