Structural Insights into the Lithium Amide-Imide Solid Solution

Joshua W. Makepeace

doi:10.1021/acs.jpcc.7b02441

Return

Structural Insights into the Lithium Amide-Imide Solid Solution

2017-05-24

Joshua W. Makepeace

William I. F. David *

DOI：10.1021/acs.jpcc.7b02441

Original

Save

View PDF

Abstract

En 中文

Solid solutions of lithium amide (LiNH2) and lithium imide (Li2NH) are present during ammonia decomposition catalysis by lithium imide and hydrogen storage and release reactions in the lithium amide lithium hydride composite. As such, they are important materials in facilitating the use of hydrogen as a sustainable energy store. In order to understand the properties of these solutions, a series of samples spanning the full stoichiometry range of the solid solution between lithium amide and lithium imide were synthesized. Powder diffraction measurements showed that a nonstoichiometric cubic phase isostructural to the high temperature phase of lithium imide was observed in all of the samples. In average stoichiometry values close to lithium amide, incomplete formation of a solid solution was observed, with tetragonal lithium amide observed in addition to the cubic nonstoichiometric phase. In analysis of neutron diffraction data, the variable stoichiometry in the structure was modeled using a golf-ball of scattering density around the nitrogen atom. This analysis revealed a greater degree of disorder in hydrogen distribution in the nonstoichiometric samples compared with lithium imide. Raman spectroscopy indicated that amide and imide groups in stoichiometric and nonstoichiometric environments can be differentiated by the frequency of the N-H stretch, with distinct bands observed for both amide and imide N-H stretches in both environments.

Keywords:

HYDROGEN STORAGE

CRYSTAL-STRUCTURE

LI3N

DECOMPOSITION

LI2NH

LINH2

PHASE

AI Summary

Key information extracted from the uploaded paper, including a brief overview, abstract, background, key highlights, visual analysis, and future outlook.