Entropic elasticity and negative thermal expansion in a simple cubic crystal
- Brookhaven National Lab. (BNL), Upton, NY (United States); Island Trees High School, Levittown, NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States); Shanghai Jiao Tong Univ. (China)
- Brookhaven National Lab. (BNL), Upton, NY (United States); GE Healthcare, Chicago, IL (United States)
- California Inst. of Technology (CalTech), Pasadena, CA (United States)
While most solids expand when heated, some materials show the opposite behavior: negative thermal expansion (NTE). In polymers and biomolecules, NTE originates from the entropic elasticity of an ideal, freely jointed chain. The origin of NTE in solids has been widely believed to be different. Our neutron scattering study of a simple cubic NTE material, ScF3, overturns this consensus. We observe that the correlation in the positions of the neighboring fluorine atoms rapidly fades on warming, indicating an uncorrelated thermal motion con-strained by the rigid Sc-F bonds. This leads us to a quantitative theory of NTE in terms of entropic elasticity of a floppy network crystal, which is in remarkable agreement with experimental results. We thus reveal the formidable universality of the NTE phenomenon in soft and hard matter.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1572369
- Report Number(s):
- BNL--212242-2019-JAAM
- Journal Information:
- Science Advances, Journal Name: Science Advances Journal Issue: 11 Vol. 5; ISSN 2375-2548
- Publisher:
- AAASCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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