Magnetic properties of mixed graphite containing both hexagonal and rhombohedral forms

Magnetic properties of graphite materials containing variable fractional amounts (up to 40%) of the Rhombahedral graphite form have been investigated by means of electron spin resonance. The variations with temperature and rhombohedral content of the Lande g-factor, ESR linewidth and paramagnetic spin-susceptibility have been analyzed. A narrow parallelism in the behaviours of the g-factor, linewidth and diamagnetic susceptibility (as the latter is known from an earlier work by Gasparoux) has been perceived, conforming to a similar parallelism between these three physical quantities present in earlier works on graphitic-type systems, but there, as a function of high-temperature-treatment and dopant concentration. From the g-value results, the g-anisotropy of the rhombohedral structure is inferred. The paramagnetic spin-susceptibility shows an increased tendency toward 2D character with increased rhombohedral content, in agreement with the theoretical predictions of McClure concerning (hypothetical) rhombohedral graphite.