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Title: A First-Principles Exploration of NaxSy Binary Phases at 1 atm and Under Pressure
Interest in Na-S compounds stems from their use in battery materials at 1 atm, as well as the potential for superconductivity under pressure. Evolutionary structure searches coupled with Density Functional Theory calculations were employed to predict stable and low-lying metastable phases of sodium poor and sodium rich sulfides at 1 atm and within 100–200 GPa. At ambient pressures, four new stable or metastable phases with unbranched sulfur motifs were predicted: Na2S3 with C 2 / c and Imm2 symmetry, C 2 -Na2S5 and C 2 -Na2S8. Van der Waals interactions were shown to affect the energy ordering of various polymorphs. At high pressure, several novel phases that contained a wide variety of zero-, one-, and two-dimensional sulfur motifs were predicted, and their electronic structures and bonding were analyzed. At 200 GPa, P 4 / m m m -Na2S8 was predicted to become superconducting below 15.5 K, which is close to results previously obtained for the β -Po phase of elemental sulfur. The structures of the most stable M3S and M4S, M = Na, phases differed from those previously reported for compounds with M = H, Li, K.  more » « less
Award ID(s):
1827815
PAR ID:
10120800
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Crystals
Volume:
9
Issue:
9
ISSN:
2073-4352
Page Range / eLocation ID:
441
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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