Hydrostatic Compression of Graphite Oxide to 49 GPa: A Raman Spectroscopic Study
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Hydrostatic Compression of Graphite Oxide to 49 GPa: A Raman Spectroscopic Study Varghese Swamy,1 Jong Boon Ooi,1 Alexander Kurnosov,2 Leonid S. Dubrovinsky,2 Alexei Y. Kuznetsov,3 and Ahmad Fauzi M. Noor4 1
School of Engineering, Monash University Malaysia, Bandar Sunway, Malaysia Bayerisches Geoinstitut, University of Bayreuth, Bavaria, Germany 3 INMETRO, DIMAT, Rio de Janeiro, Brazil 4 School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Penang, Malaysia 2
ABSTRACT The compression and decompression behaviors of graphite oxide have been investigated using in situ Raman measurements in a diamond-anvil cell at room temperature. The so-called G band (in-plane E2g mode ~1600 cm-1) was followed to 49 GPa during compression and back to ambient under decompression. The Raman frequency of the G band increases sublinearly with increasing hydrostatic pressure, eventually nearly flattening out at the highest pressure measured. This trend is reversed upon decompression, fully recovering to the ambient spectrum. The increased broadening suggests a reversible disordering of the structure without significant sp2-sp3 rehybridization under pressure. INTRODUCTION The compression behaviors of graphene and related layered carbon structures [1] have been the subject of a number of recent studies [2-13]. These studies were intended not only for a deeper fundamental understanding of the mechanical properties and pressure-induced phase transitions of these important materials, but also for developing applications wherein strain engineering could be used to modify their electronic properties. Proctor et al. [3] observed compression behaviors intrinsically similar to that of graphite for both supported and unsupported mono-, bi-, and few-layer graphene at low pressures (18 GPa. Filintoglou et al. [13] investigated the influence of polar (methanol-ethanol) and non-polar (Flourinert) pressure-transmitting medium on the high-pressure behavior of Cu-supported graphene using Raman spectroscopy. Their results obtained to 6 GPa suggest both G and 2D bands (see below) display similar pressure slopes, independent of the pressure medium used. In a DAC-XRD and Raman study of reduced graphene oxide, Pandey et al. [12] inferred pressure-induced flattening of the puckered graphene layers and slightly increased reversible disorder, but no phase transition. Graphite oxide has been studied under relatively low pressures (
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