Premium
The Relative Thermodynamic Stability of Diamond and Graphite
Author(s) -
White Mary Anne,
Kahwaji Samer,
Freitas Vera L. S.,
Siewert Riko,
Weatherby Joseph A.,
Ribeiro da Silva Maria D. M. C.,
Verevkin Sergey P.,
Johnson Erin R.,
Zwanziger Josef W.
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202009897
Subject(s) - diamond , graphite , thermodynamics , chemical stability , density functional theory , degenerate energy levels , chemistry , entropy (arrow of time) , materials science , computational chemistry , physics , organic chemistry , quantum mechanics
Recent density‐functional theory (DFT) calculations raised the possibility that diamond could be degenerate with graphite at very low temperatures. Through high‐accuracy calorimetric experiments closing gaps in available data, we reinvestigate the relative thermodynamic stability of diamond and graphite. For T <400 K, graphite is always more stable than diamond at ambient pressure. At low temperatures, the stability is enthalpically driven, and entropy terms add to the stability at higher temperatures. We also carried out DFT calculations: B86bPBE‐25X‐XDM//B86bPBE‐XDM and PBE0‐XDM//PBE‐XDM results overlap with the experimental − T Δ S results and bracket the experimental values of Δ H and Δ G , displaced by only about 2× the experimental uncertainty. Revised values of the standard thermodynamic functions for diamond are Δ f H o =−2150±150 J mol −1 , Δ f S o =3.44±0.03 J K −1 mol −1 and Δ f G o =−3170±150 J mol −1 .