Accurate Measurement of the Cleavage Energy of Graphite

TL;DR

This paper presents the first direct and highly accurate experimental measurement of graphite's cleavage energy using a novel method based on self-retraction, providing a reliable benchmark for theoretical models.

Contribution

The study introduces a new experimental approach to measure graphite's cleavage energy accurately, resolving previous inconsistencies and offering a benchmark for theoretical validation.

Findings

Measured CE of incommensurate graphite: 0.37 ± 0.01 J/m2

CE is nearly invariant with temperature and twist angle

Calculated CE for ideal ABAB stacking: 0.39 ± 0.02 J/m2

Abstract

The basal plane cleavage energy (CE) of graphite is a key material parameter for understanding many of the unusual properties of graphite, graphene, and carbon nanotubes. The CE is equal to twice the surface energy and is closely related to the interlayer binding energy and exfoliation energy of graphite. Nonetheless, a wide range of values for these properties have been reported and no consensus has yet emerged as to their magnitude. Here, we report the first direct, accurate experimental measurement of the CE of graphite using a novel method based on the recently discovered self-retraction phenomenon in graphite. The measured value, 0.37 +/- 0.01 J/m2 for the incommensurate state of bicrystal graphite, is nearly invariant with respect to temperature (from 22{\deg}C to 198{\deg}C) and bicrystal twist angle, and insensitive to impurities (from the atmosphere). The cleavage energy for the ideal ABAB graphite stacking, 0.39 +/- 0.02 J/m2, is calculated based upon a combination of the measured CE and a theoretical calculation. These experimental measurements are ideal for use in evaluating the efficacy of competing theoretical approaches.