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Title: Advanced Synthesis of Na 4Si 24

Abstract

The recently discovered orthorhombic allotrope of silicon, Si 24, is an exciting prospective material for the future of solar energy due to a quasi-direct bandgap near 1.3 eV, coupled with the abundance and environmental stability of silicon. Synthesized via precursor Na 4Si 24 at high temperature and pressure (~850 °C, 9 GPa), typical synthesis results have yielded polycrystalline samples with crystallites on the order of 20 μm. Several approaches to increase the crystal size have yielded success, including in-situ thermal spikes and refined selection of the starting materials. Microstructural analysis suggests that coherency exists between diamond silicon (d-Si) and Na 4Si 24. This hypothesis has led to the successful attempts at single crystal synthesis by selecting large crystals of d-Si along with metallic Na as the precursors rather than powdered and mixed precursor material. The new synthesis approach has yielded single crystals of Na 4Si 24 greater than 100 μm. These results represent a breakthrough in synthesis that enables further characterization and utility. The promise of Si 24 for the future of solar energy generation and efficient electronics is strengthened through these advances in synthesis.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research in Extreme Environments (EFree)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1470612
DOE Contract Number:  
SC0001057
Resource Type:
Journal Article
Journal Name:
MRS Advances
Additional Journal Information:
Journal Volume: 3; Journal Issue: 25; Related Information: EFree partners with Carnegie Institution of Washington (lead); California Institute of Technology; Colorado School of Mines; Cornell University; Lehigh University; Pennsylvania State University; Journal ID: ISSN 2059-8521
Publisher:
Materials Research Society (MRS)
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, charge transport, mesostructured materials, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Guerette, Michael, Strobel, Timothy A., Zhang, Haidong, Juhl, Stephen, Alem, Nasim, Lokshin, Konstantin, Krishna, Lakshmi, and Craig Taylor, P. Advanced Synthesis of Na4Si24. United States: N. p., 2018. Web. doi:10.1557/adv.2018.44.
Guerette, Michael, Strobel, Timothy A., Zhang, Haidong, Juhl, Stephen, Alem, Nasim, Lokshin, Konstantin, Krishna, Lakshmi, & Craig Taylor, P. Advanced Synthesis of Na4Si24. United States. doi:10.1557/adv.2018.44.
Guerette, Michael, Strobel, Timothy A., Zhang, Haidong, Juhl, Stephen, Alem, Nasim, Lokshin, Konstantin, Krishna, Lakshmi, and Craig Taylor, P. Mon . "Advanced Synthesis of Na4Si24". United States. doi:10.1557/adv.2018.44.
@article{osti_1470612,
title = {Advanced Synthesis of Na4Si24},
author = {Guerette, Michael and Strobel, Timothy A. and Zhang, Haidong and Juhl, Stephen and Alem, Nasim and Lokshin, Konstantin and Krishna, Lakshmi and Craig Taylor, P.},
abstractNote = {The recently discovered orthorhombic allotrope of silicon, Si24, is an exciting prospective material for the future of solar energy due to a quasi-direct bandgap near 1.3 eV, coupled with the abundance and environmental stability of silicon. Synthesized via precursor Na4Si24 at high temperature and pressure (~850 °C, 9 GPa), typical synthesis results have yielded polycrystalline samples with crystallites on the order of 20 μm. Several approaches to increase the crystal size have yielded success, including in-situ thermal spikes and refined selection of the starting materials. Microstructural analysis suggests that coherency exists between diamond silicon (d-Si) and Na4Si24. This hypothesis has led to the successful attempts at single crystal synthesis by selecting large crystals of d-Si along with metallic Na as the precursors rather than powdered and mixed precursor material. The new synthesis approach has yielded single crystals of Na4Si24 greater than 100 μm. These results represent a breakthrough in synthesis that enables further characterization and utility. The promise of Si24 for the future of solar energy generation and efficient electronics is strengthened through these advances in synthesis.},
doi = {10.1557/adv.2018.44},
journal = {MRS Advances},
issn = {2059-8521},
number = 25,
volume = 3,
place = {United States},
year = {2018},
month = {1}
}

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