Two-Dimensional and Three-Dimensional Tetrel-Arsenide Frameworks Templated by Li and Cs Cations
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Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).
History
The Department of Chemistry was founded in 1880.
Dates of Existence
1880-present
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- College of Liberal Arts and Sciences (parent college)
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Abstract
Two new ternary tetrel pnictide phases, Li1.08Ge4.92As7 and Cs0.11Zn0.05Si0.95As, have been synthesized. Both compounds crystallize in new structure types, which demonstrate the flexibility of Ge(Si)–As layers when accommodating electropositive cations of various sizes. Li1.08Ge4.92As7 displays a Ge-As layer motif that has not been observed in ternary Ge-As systems, while Cs0.11Zn0.05Si0.95As exhibits a 3D framework composed of fragments of the 2D parent-phase SiAs. For Li1.08Ge4.92As7, a combination of computational modeling and solid-state 7Li MAS NMR was used to establish the correct crystal structure with one mixed occupied Ge/Li site. The compositions of the phases were confirmed through energy-dispersive X-ray spectroscopy. Transport properties and UV–Vis spectroscopy reveal both reported compounds to be semiconductors. Cs0.11Zn0.05Si0.95As shows high thermal stability with congruent melting at 1300 K and an exceptionally low thermal conductivity of 0.5 W m–1 K–1 at 300 K. Temperature-dependent Li-ion hopping dynamics in Li1.08Ge4.92As7 was characterized using 7Li solid-state NMR.