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Title: Cage disorder and gas encapsulation as routes to tailor properties of inorganic clathrates

Authors:
; ORCiD logo; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1398630
Grant/Contract Number:
FG02- 04ER46145
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 131; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-07 09:19:34; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

Citation Formats

Khabibullin, A. R., Huan, T. D., Nolas, G. S., and Woods, L. M. Cage disorder and gas encapsulation as routes to tailor properties of inorganic clathrates. United States: N. p., 2017. Web. doi:10.1016/j.actamat.2017.03.059.
Khabibullin, A. R., Huan, T. D., Nolas, G. S., & Woods, L. M. Cage disorder and gas encapsulation as routes to tailor properties of inorganic clathrates. United States. doi:10.1016/j.actamat.2017.03.059.
Khabibullin, A. R., Huan, T. D., Nolas, G. S., and Woods, L. M. Thu . "Cage disorder and gas encapsulation as routes to tailor properties of inorganic clathrates". United States. doi:10.1016/j.actamat.2017.03.059.
@article{osti_1398630,
title = {Cage disorder and gas encapsulation as routes to tailor properties of inorganic clathrates},
author = {Khabibullin, A. R. and Huan, T. D. and Nolas, G. S. and Woods, L. M.},
abstractNote = {},
doi = {10.1016/j.actamat.2017.03.059},
journal = {Acta Materialia},
number = C,
volume = 131,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.actamat.2017.03.059

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  • Samples with the type-I clathrate composition Ba{sub 8}Ni{sub x}Si{sub 46-x} have been synthesized and their structure and thermoelectric properties characterized. Microprobe analysis indicates the Ni incorporation to be 2.62{<=}x{<=}3.53. The x=3.5 phase crystallizes in the type-I clathrate structure (space group: Pm-3n) with a lattice parameter of 10.2813(3) A. The refined composition was Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}, with small vacancies, 0.4 and 0.5 atoms per formula unit, at the 2a and 6c sites, respectively. The position of the Ba2 atom in the large cage was modeled using a 4-fold split position (24j site), displaced 0.18 A from the cage center (6dmore » site). The volume of the large cage is calculated to be 146 A{sup 3}, smaller than other clathrates with similar cation displacement. The sample shows n-type behavior with a maximum of -50 {mu}V/K at 823 K above which the Seebeck coefficient decreases, suggesting mixed carriers. Lattice thermal conductivity, {kappa}{sub l}, is 55 mW/K above 600 K. - Graphical abstract: Seebeck coefficient and resistivity of the type-I clathrate Ba{sub 8}Ni{sub 3.5}Si{sub 41.0}. Structure show's large displacement of the Ba cation in the large cage (6c site). Highlights: Black-Right-Pointing-Pointer Crystal structure of the Ba{sub 8}Ni{sub 3.5}Si{sub 41.0} reported. Black-Right-Pointing-Pointer Vacancies at the 2a and 6c sites. Black-Right-Pointing-Pointer Large disorder of Ba guest atom, 0.18 A from cage center. Black-Right-Pointing-Pointer Structure is compared to Ba{sub 8}Si{sub 46} and other type-I clathrates. Black-Right-Pointing-Pointer Max Seebeck of -50.7 {mu}V/C at 798.4 K, thermal conductivity {approx}55 mW/K.« less
  • Temperature dependent synchrotron powder diffraction and single crystal neutron diffraction data are used for probing the vibrational states and disorder in type I clathrates Ba{sub 8}Ga{sub 16}Si{sub 30}, Ba{sub 8}Ga{sub 16}Ge{sub 30}, Ba{sub 8}In{sub 16}Ge{sub 30}, and Sr{sub 8}Ga{sub 16}Ge{sub 30}. If an empirical disorder term is included, the temperature dependence of the atomic displacement factors (ADPs) of the framework and guest atoms can be described by a Debye and Einstein model, respectively. None of the guest atoms in the large cages are located in the center and the vibrational frequencies ({theta}{sub E}) are of the order 80 K ormore » larger for all structures, in good agreement with theoretical predictions. Even though the Sr ADPs are larger than the Ba ADPs in all the clathrates, the data show that {theta}{sub E} of Sr in Sr{sub 8}Ga{sub 16}Ge{sub 30} is larger than for the Ba atoms. This is due to stronger guest-host chemical bonding in Sr{sub 8}Ga{sub 16}Ge{sub 30}. Since {theta}{sub E} of Sr has been reported to be much smaller in the literature we have also measured the specific heat of Sr{sub 8}Ga{sub 16}Ge{sub 30} with Ba{sub 8}Ga{sub 16}Ge{sub 30} as a reference. It is found that localized excitations with a characteristic energy of approximately 35 K exist in both compounds, however, the total number of states is too low to be associated with either tunneling states or localized vibration of each of the guest atoms.« less
  • No abstract prepared.
  • A critical challenge in nanoparticle (NP) surface functionalization is to label the NP surface with a single copy of a functional group or to display multiple, unique molecules on the NP surface with control of the orientation and intermolecular distance. This challenge was addressed with the construction of a spatially addressable, self-assembling DNA origami nanocage that encapsulates gold nanoparticles and interrupts its surface symmetry