Control of thermal expansion in a low-density framework modification of silicon
- California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)
- Illinois Inst. of Technology, Chicago, IL (United States); North Central College, Naperville, IL (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- Univ. of South Florida, Tampa, FL (United States)
The low-density clathrate-II modification of silicon, Si136, contains two distinct cage-like voids large enough to accommodate various types of guest atoms which influence both the host structure and its properties. Although the linear coefficient of thermal expansion of Si136 (293 K < T < 423 K) is only about 20% larger than that of the ground state α-Si (diamond structure), the coefficient of thermal expansion monotonically increases by more than 150% upon filling the framework cages with Na atoms in NaxSi136 (0 < x < 24), ranging from α = 2.6 x 10–6 K–1 (x = 0) to 6.8 × 10–6 K–1 (extrapolated to x = 24) by only varying the Na content, x. Taken together with the available heat capacity and bulk modulus data, the dramatic increase in thermal expansion can be attributed to an increase in the mode-averaged Grüneisen parameter by a factor of nearly 3 from x = 0 to x = 24. Furthermore, these results highlight a potential mechanism for tuning thermal expansion, whereby guest atoms are incorporated into the voids of rigid, covalently bonded inorganic frameworks to influence the lattice dynamics.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- SDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-06CH11357; DMR-1400957
- OSTI ID:
- 1436777
- Alternate ID(s):
- OSTI ID: 1435392
- Journal Information:
- Applied Physics Letters, Vol. 112, Issue 18; ISSN 0003-6951
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
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journal | April 2019 |
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