Anomalous phonon softening of G-band in compressed graphitic carbon nitride due to strong electrostatic repulsion

• Graphitic carbon nitride (C2N and C3N) with various p electron distributions on layers have been studied under pressure through acombined theoretical and experimental approach and a comparison with graphite. It is found that as these materials transform into lowcompressibility phases in the pressure range from 15 to 45 GPa, strong electrostatic repulsion between p electrons and in-plane sp2 electronsmay distort and soften the sp2 bonds, leading to anomalous pressure evolutions of the intralayer phonon vibrations, such as a plateau-likebehavior of E2g mode (G-band) in C2N and C3N. This also causes a slow increase in the resistivity/resistance of C2N and C3N as pressureincreases, and the gradual interlayer bonding leads to an abrupt increase in resistance of the materials but with different pressure responsesdue to their different p electron distributions. Moreover, the intensity enhancement of the G band in both CN materials may be related totheir electronic structure changes. The results deepen our understanding of the effects of p electron distribution on the structural transitionof graphitic materials and may explain some unexplained in previous studies.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)