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Abstract:
The crystal structure of a ternary sulfide with the approximate
composition LiCuS, which is a promising candidate for
environment-friendly battery and solar cell materials is reported. The
crystal structure was solved by a combination of neutron and X-ray
powder diffraction data, and Li-7 solid-state NMR analysis. A yellow
powder, Li1.1Cu0.9S, was obtained by the reaction of CuS with a slight
excess of Li metal. The compound crystallizes in the Na3AgO2 structure
type in the space group Ibam. An idealized crystal structure of
Li1.1Cu0.9S can be derived from the cubic Li2S structure by moving a
part of the Li along the c axis so that these Li atoms become linearly
coordinated by S. All the metal sites are occupied by randomly mixed Li
and Cu atoms; however, there is a strong preference for linear
coordination by Cu. The density functional theory calculations show that
Li1.1Cu0.9S is a direct band-gap semiconductor with an energy gap of
1.95 eV in agreement with experimental data. (C) 2016 The Authors.
Published by Elsevier Masson SAS. This is an open access article under
the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
