Related Experiment Video
Updated: May 9, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
The unusual and the expected in the Si/C phase diagram
Guoying Gao1, N W Ashcroft, Roald Hoffmann
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Abstract:
In the Si/C phase diagram, the only stable phases at P = 1 atm are the numerous polytypes of the simplest 1:1 stoichiometry, SiC. However, many metastable yet likely to be kinetically persistent phases can be found for almost any composition. Given the instability of simple graphite-type structures with considerable Si content, we thought these metastables would be only of the diamondoid class. Indeed they are for Si3C, a stoichiometry we studied on the silicon-rich side of the phase diagram. Yet on the carbon-rich side, which we chose to explore computationally with SiC3, there was a surprise in store, a series of unusual metastable structures. The most striking of these had the appearance of a collapsed graphite structure, with benzenoid C6 units and SiSi bridges between layers. This SiC3 structure is related to known meta-(1,3,5)cyclophanes. Three other metastable structures featured layers with all carbon polyene and polyphenylene arrays. Some of these can be metallic, as we have found.
More Related Videos
04:09Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics
Published on: August 30, 2024
11:50Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions
Published on: June 13, 2015
Related Concept Videos
Phase Diagrams
Phase Diagram
Phase Diagram
Phase Diagrams of Ternary Systems
The Phase Rule
Solid–Solid Solutions