Dimension Effect of Nanocarbon Precursors on Diamond Synthesis and Transformation Mechanism under Extreme Conditions

TL;DR

This study explores how the dimensions of nanocarbon precursors influence diamond synthesis under extreme conditions, revealing distinct transformation pathways for different nanostructures and providing insights into the phase transition mechanisms.

Contribution

It demonstrates the dimension-dependent effects of nanocarbon precursors on diamond formation and elucidates the transformation mechanisms under high temperature and pressure.

Findings

Both CNCs and CNTs undergo collapse and graphitization before forming diamond.

The dimension of nanocarbon precursors affects the pressure-temperature conditions for diamond synthesis.

Distinct transformation pathways are observed for 0D and 1D nanocarbon precursors.

Abstract

Diamond holds significant promise for a wide range of applications due to its exceptional physicochemical properties. Investigating the controlled diamond preparation from nanocarbon precursors with varying dimensions is crucial to optimize the transition conditions and even elucidate the daunting transformation mechanism, however, this remains outstanding challenge despite considerable effort. Herein, we report the imperative dimension effect of nanocarbon precursors on diamond synthesis and physical mechanism under high temperature and high pressure, by comparing the distinct transition processes of zero-dimensional (0D) carbon nanocages (CNCs) and one-dimensional (1D) carbon nanotubes (CNTs) from conventional graphite. The optical and structural characterizations evidently demonstrated that both 0D CNCs and 1D CNTs first undergo collapse and graphitization, followed by the formation of mixed amorphous carbon with embedded diamond clusters, eventually leading to cubic diamond. The plotted pressure-temperature diagram exhibits the unique dimension effect of carbon nanomaterials to diamond transformation. These results provide valuable insights into the phase transition mechanisms of diamond synthesis and its derivatives under extreme conditions.