共 49 条
Electronic origin of negative thermal expansion in samarium hexaboride revealed by X-ray diffraction and total scattering
被引:1
作者:
Li, Li
[1
]
Dove, Martin T.
[2
,3
,4
]
Wei, Zhongsheng
[4
]
Phillips, Anthony E.
[4
]
Keeble, Dean S.
[5
]
机构:
[1] Civil Aviat Flight Univ China, Coll Sci, 46 Nanchang Rd, Guanghan 618307, Sichuan, Peoples R China
[2] Sichuan Univ, Inst Atom & Mol Phys, Chengdu 610065, Sichuan, Peoples R China
[3] Dongguan Univ Technol, Sch Mech Engn, 1st Daxue Rd,Songshan Lake, Dongguan 523000, Guangdong, Peoples R China
[4] Queen Mary Univ London, Sch Phys & Chem Sci, Mile End Rd, London E14NS, England
[5] Diamond Light Source Ltd, Harwell Sci & Innovat Campus, Didcot OX110DE, Oxon, England
基金:
中国国家自然科学基金;
关键词:
NEUTRON-DIFFRACTION;
CORRELATION-GAP;
SMB6;
SEMICONDUCTOR;
INSULATOR;
BEHAVIOR;
CRYSTAL;
D O I:
10.1039/d3cp05954e
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Samarium hexaboride, SmB6, is a negative thermal expansion (NTE) material whose structure is similar to other known NTE materials such as the family of Prussian blues. In the Prussian blues, NTE is due to a phonon mechanism, but we recently showed from DFT calculations that this is unlikely in SmB6 (Li et al., Phys. Chem. Chem. Phys. 2023, 25, 10749). We now report experimental X-ray diffraction and pair distribution function analysis of this material in the temperature range 20-300 K. The interatomic distances shown by both methods are consistent with the NTE instead arising from an electronic effect, by which the samarium atoms lose electrons and thus have a smaller ionic radius as the temperature increases. Using X-ray diffraction and measurements of the pair distribution function we show that negative thermal expansion in SmB6 arises from charge transfer rather than the traditional tension effect.
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页码:7664 / 7673
页数:10
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