Ye Cao, Hongxing Song, Xiaozhen Yan, Hao Wang, Yufeng Wang, Fengchao Wu, Leilei Zhang, Qiang Wu and Huayun Geng
{"title":"高压下 U-He 化合物结构和热力学性质的理论研究","authors":"Ye Cao, Hongxing Song, Xiaozhen Yan, Hao Wang, Yufeng Wang, Fengchao Wu, Leilei Zhang, Qiang Wu and Huayun Geng","doi":"10.1039/D4CP02037E","DOIUrl":null,"url":null,"abstract":"<p >Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of uranium, it is difficult for helium to react with uranium because of its chemical inertness. Therefore, bubbles will be formed inside uranium, which could greatly reduce the performance of uranium or cause safety problems. Additionally, nuclear materials are usually operated in an environment of high-temperature and high-pressure, so it is necessary to figure out the exact state of helium inside uranium under extreme conditions. Here, we explored the structural stability of the U–He system under high pressure and high temperature by using density functional theory calculations. Two metastable phases are found between 50 and 400 GPa: U<small><sub>4</sub></small>He with space group <em>Fmmm</em> and U<small><sub>6</sub></small>He with space group <em>P</em><img>. Both are metallic and adopt layered structures. Electron localization function calculation combined with charge density difference analysis indicates that there are covalent bonds between U and U atoms in both <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He. Regarding the elastic modulus of α-U, the addition of helium has certain influence on the mechanical properties of uranium. Besides, first-principles molecular dynamics simulations were carried out to study the dynamical behavior of <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He at high-temperature. It was found that <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He undergo one-dimensional superionic phase transitions at 150 GPa. Our study revealed the exotic structure of U–He compounds beyond the formation of bubbles under high-pressure and high-temperature, which might be relevant to the performance and safety issues of nuclear materials under extreme conditions.</p>","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Theoretical study of the structural and thermodynamic properties of U–He compounds under high pressure†\",\"authors\":\"Ye Cao, Hongxing Song, Xiaozhen Yan, Hao Wang, Yufeng Wang, Fengchao Wu, Leilei Zhang, Qiang Wu and Huayun Geng\",\"doi\":\"10.1039/D4CP02037E\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of uranium, it is difficult for helium to react with uranium because of its chemical inertness. Therefore, bubbles will be formed inside uranium, which could greatly reduce the performance of uranium or cause safety problems. Additionally, nuclear materials are usually operated in an environment of high-temperature and high-pressure, so it is necessary to figure out the exact state of helium inside uranium under extreme conditions. Here, we explored the structural stability of the U–He system under high pressure and high temperature by using density functional theory calculations. Two metastable phases are found between 50 and 400 GPa: U<small><sub>4</sub></small>He with space group <em>Fmmm</em> and U<small><sub>6</sub></small>He with space group <em>P</em><img>. Both are metallic and adopt layered structures. Electron localization function calculation combined with charge density difference analysis indicates that there are covalent bonds between U and U atoms in both <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He. Regarding the elastic modulus of α-U, the addition of helium has certain influence on the mechanical properties of uranium. Besides, first-principles molecular dynamics simulations were carried out to study the dynamical behavior of <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He at high-temperature. It was found that <em>Fmmm</em>-U<small><sub>4</sub></small>He and <em>P</em><img>-U<small><sub>6</sub></small>He undergo one-dimensional superionic phase transitions at 150 GPa. Our study revealed the exotic structure of U–He compounds beyond the formation of bubbles under high-pressure and high-temperature, which might be relevant to the performance and safety issues of nuclear materials under extreme conditions.</p>\",\"PeriodicalId\":99,\"journal\":{\"name\":\"Physical Chemistry Chemical Physics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.9000,\"publicationDate\":\"2024-06-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Physical Chemistry Chemical Physics\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://pubs.rsc.org/en/content/articlelanding/2024/cp/d4cp02037e\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physical Chemistry Chemical Physics","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/cp/d4cp02037e","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Theoretical study of the structural and thermodynamic properties of U–He compounds under high pressure†
Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of uranium, it is difficult for helium to react with uranium because of its chemical inertness. Therefore, bubbles will be formed inside uranium, which could greatly reduce the performance of uranium or cause safety problems. Additionally, nuclear materials are usually operated in an environment of high-temperature and high-pressure, so it is necessary to figure out the exact state of helium inside uranium under extreme conditions. Here, we explored the structural stability of the U–He system under high pressure and high temperature by using density functional theory calculations. Two metastable phases are found between 50 and 400 GPa: U4He with space group Fmmm and U6He with space group P. Both are metallic and adopt layered structures. Electron localization function calculation combined with charge density difference analysis indicates that there are covalent bonds between U and U atoms in both Fmmm-U4He and P-U6He. Regarding the elastic modulus of α-U, the addition of helium has certain influence on the mechanical properties of uranium. Besides, first-principles molecular dynamics simulations were carried out to study the dynamical behavior of Fmmm-U4He and P-U6He at high-temperature. It was found that Fmmm-U4He and P-U6He undergo one-dimensional superionic phase transitions at 150 GPa. Our study revealed the exotic structure of U–He compounds beyond the formation of bubbles under high-pressure and high-temperature, which might be relevant to the performance and safety issues of nuclear materials under extreme conditions.
期刊介绍:
Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions.
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