Explaining stability of transition metal carbides - and why TcC does not exist

We analyze the formation of transition metal (TM) carbides, as determined by the strength of TM-TM and TM-C bonds, as well as lattice distortions induced by C interstitials. With increasing filling of the d-band of TMs, TM-C bonds become increasingly weak from the left of the periodic table to the r...

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Bibliographic Details
Published in:RSC advances 2016-01, Vol.6 (2), p.16197-1622
Main Authors: Wang, Qinggao, German, Konstantin E, Oganov, Artem R, Dong, Huafeng, Feya, Oleg D, Zubavichus, Ya. V, Murzin, V. Yu
Format: Article
Language:English
Subjects:
Carbides
Distortion
Formations
Graphite
Lattices
Periodic table
Technetium
Transition metals
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Summary:We analyze the formation of transition metal (TM) carbides, as determined by the strength of TM-TM and TM-C bonds, as well as lattice distortions induced by C interstitials. With increasing filling of the d-band of TMs, TM-C bonds become increasingly weak from the left of the periodic table to the right, with fewer and fewer C atoms entering the TMs lattice. Technetium (Tc) turns out to be a critical point for the formation of carbides, guiding us to resolve a long-standing dispute. The predicted Tc carbides, agreeing with measured X-ray absorption spectra, should decompose to cubic Tc and graphite above 2000 K. Consequently, we show that what has been claimed as TcC (with rocksalt structure) is actually a high-temperature cubic phase of elemental technetium. A simple understanding on the trend of stability for transition metal carbides.
ISSN:2046-2069
2046-2069
DOI:10.1039/c5ra24656c