Crossover of thermal expansion from positive to negative by removing the excess fluorines in cubic ReO3-type TiZrF7-x
- Chinese Academy of Sciences (CAS), Hefei (China). Key Lab. of Materials Physics and Inst. of Solid State Physics; Univ. of Science and Technology of China, Hefei (China)
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
- Hefei Univ. of Technology (China). Lab. of Amorphous Materials and School of Materials Science and Engineering
- Chinese Academy of Sciences (CAS), Hefei (China). Key Lab. of Materials Physics and Inst. of Solid State Physics
- Chinese Academy of Sciences (CAS), Hefei (China). High Magnetic Field Lab.
- Chinese Academy of Sciences (CAS), Hefei (China). Key Lab. of Materials Physics, Inst. of Solid State Physics and High Magnetic Field Lab.
Here, we report the crossover of the coefficient of thermal expansion (CTE) from positive to negative by withdrawing the excess fluorines in ReO3-type TiZrF7-x (x = 0, 0.5 and 1) compounds. The average volumetric CTE between 300 K and 623 K changes from 8.07 ppm K-1 for x = 0, to 0.66 ppm K-1 for x = 0.5 and finally to -6.09 ppm K-1 for x = 1. After withdrawing the excess fluorines, the lattice expands and the edge-sharing polyhedra partially transform to corner-sharing ones, which enhances the transverse vibrations of fluorines and thus accounts for the crossover of CTE. Moreover, these compounds are narrow-gap semiconductors with the energy gap decreasing with x. NTE may also be achievable in other fluorine-excess cubic fluorides by removing the excess fluorines, which opens up a new avenue for exploring the NTE in fluorides.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Natural Science Foundation of China (NSFC)
- Grant/Contract Number:
- SC0012704; QYZDB-SSW-SLH015; 51322105; U1632158
- OSTI ID:
- 1463853
- Alternate ID(s):
- OSTI ID: 1434158
- Report Number(s):
- BNL-207923-2018-JAAM; JMCCCX
- Journal Information:
- Journal of Materials Chemistry C, Vol. 6, Issue 19; ISSN 2050-7526
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
On the switching between negative and positive thermal expansion in framework materials
|
journal | May 2019 |
On the switching between negative and positive thermal expansion in framework materials | text | January 2019 |
On the switching between negative and positive thermal expansion in framework materials
|
text | January 2019 |
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