The Crystal Structure of Al4SiC4 Revisited
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F24%3A00586605" target="_blank" >RIV/61389005:_____/24:00586605 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1021/acs.inorgchem.4c00560" target="_blank" >https://doi.org/10.1021/acs.inorgchem.4c00560</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1021/acs.inorgchem.4c00560" target="_blank" >10.1021/acs.inorgchem.4c00560</a>
Alternative languages
Result language
angličtina
Original language name
The Crystal Structure of Al4SiC4 Revisited
Original language description
Al4SiC4 is a ternary wide-band-gap semiconductor with a high strength-to-weight ratio and excellent oxidation resistance. It consists of slabs of Al4C3 separated by SiC layers with the space group of P6(3)mc. The space group allows Si to occupy two different 2a Wykoff sites, with previous studies reporting that Si occupies only one of the two sites, giving it an ordered structure. Another hitherto unexplored possibility is that Si can be randomly distributed on both 2a sites. In this work, we revisit the published ordered crystal structure using experimental methods and density functional theory (DFT). Al4SiC4 was synthesized by high-temperature sintering at 1800 degrees C from a powder mixture of Al4C3 and SiC. Neutron diffraction confirmed that Al4SiC4 crystallized with the space group of P6(3)mc, with diffraction patterns that could be fitted to both the ordered and the disordered structures. Scanning transmission electron microscopy, however, provided clear evidence supporting the latter, with DFT calculations further confirming that it is 0.16 eV lower in energy per Al4SiC4 formula unit than the former. TEM analysis revealed Al vacancies in some of the atomic layers that can introduce p-type doping and direct band gaps of 0.7 and 1.2 eV, agreeing with our optical measurements. Finally, we propose that although the calculated formation energy of the Al vacancies is high, the vacancies are stabilized by entropy effects at the high synthesis temperature. This indicates that the cooling procedure after high-temperature synthesis can be important in determining the vacancy content and the electronic properties of Al4SiC4.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10302 - Condensed matter physics (including formerly solid state physics, supercond.)
Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Inorganic Chemistry
ISSN
0020-1669
e-ISSN
1520-510X
Volume of the periodical
63
Issue of the periodical within the volume
23
Country of publishing house
US - UNITED STATES
Number of pages
10
Pages from-to
10490-10499
UT code for WoS article
001232686900001
EID of the result in the Scopus database
2-s2.0-85194399791