Negative thermal expansion in NbF3 and NbOF2:A comparative theoretical study

• 作者: Mingyue Zhang Chunyan Wang Yinuo Zhang Qilong Gao Yu Jia
• 来源期刊: 中国物理B（英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
• 页码范围: 627-632
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/1674-1056/abe376

摘要

Thermal expansion control is always an obstructive factor and challenging in high precision engineering field.Here,the negative thermal expansion of NbF3 and NbOF2 was predicted by first-principles calculation with density functional theory and the quasi-harmonic approximation (QHA).We studied the total charge density,thermal vibration,and lattice dynamic to investigate the thermal expansion mechanism.We found that the presence of O induced the relatively strong covalent bond in NbOF2,thus weakening the transverse vibration of F and O in NbOF2,compared with the case of NbF3.In this study,we proposed a way to tailor negative thermal expansion of metal fluorides by introducing the oxygen atoms.The present work not only predicts two NTE compounds,but also provides an insight on thermal expansion control by designing chemical bond type.