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Title: The low-temperature structural behavior of sodium 1-carba-closo-decaborate: NaCB9H10

Two ordered phases of the novel solid superionic conductor sodium 1-carba-closo-decaborate (NaCB9H10) were identified via synchrotron x-ray powder diffraction in combination with first-principles calculations and neutron vibrational spectroscopy. A monoclinic packing of the large ellipsoidal CB9H10- anions prevails at the lowest temperatures, but a first-order transformation to a slightly modified orthorhombic packing is largely complete by 240 K. The CB9H10- anion orientational alignments and Na+ cation interstitial sitings in both phases are arranged so as to minimize the cation proximities to the uniquely more positive C-bonded H atoms of the anions. These results provide valuable structural information pertinent to understanding the relatively low-temperature, entropy-driven, order-disorder phase transition for this compound.
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0022-4596
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 243
Research Org:
NREL (National Renewable Energy Laboratory (NREL), Golden, CO (United States))
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Program (EE-3F)
Country of Publication:
United States
36 MATERIALS SCIENCE density functional theory; diffraction; ionic conductors; monocarba-closo-decaborates; sodium borohydrides; vibrational spectroscopy