Atomistic Modeling of the Negative Thermal Expansion in δ- Plutonium Based on the Two-State Description
| Autor: | A. C. Lawson, Tongsik Lee, S. P. Chen, Michael I. Baskes, Steven M. Valone |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
plutonium
Monte Carlo method Binding energy chemistry.chemical_element engineering.material lcsh:Technology Article modified embedded atom method Negative thermal expansion Phase (matter) Atom negative thermal expansion Invar Weiss model General Materials Science lcsh:Microscopy lcsh:QC120-168.85 lcsh:QH201-278.5 Condensed matter physics lcsh:T Atmospheric temperature range Plutonium chemistry lcsh:TA1-2040 engineering lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering lcsh:Engineering (General). Civil engineering (General) lcsh:TK1-9971 |
| Zdroj: | Materials; Volume 5; Issue 6; Pages: 1040-1054 Materials, Vol 5, Iss 6, Pp 1040-1054 (2012) Materials |
| ISSN: | 1996-1944 |
| DOI: | 10.3390/ma5061040 |
| Popis: | The δ phase of plutonium with the fcc structure exhibits an unusual negative thermal expansion (NTE) over its narrow temperature range of stability, 593–736 K. An accurate description of the anomalous high-temperature volume effect of plutonium goes beyond the current capability of electronic-structure calculations. We propose an atomistic scheme to model the thermodynamic properties of δ-Pu based on the two-state model of Weiss for the Invar alloys, inspired by the simple free-energy analysis previously conducted by Lawson et al. The two-state mechanism is incorporated into the atomistic description of a many-body interacting system. Two modified embedded atom method potentials are employed to represent the binding energies of two competing electronic states in δ-Pu. We demonstrate how the NTE takes place in δ-Pu by means of Monte Carlo simulations implemented with the two-state mechanism. |
| Databáze: | OpenAIRE |
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