abstract
Graphene/silicon nitride (Si3N4) composites with high fraction of few layered graphene are synthesized by an in situ reduction of graphene oxide (GO) during spark plasma sintering (SPS) of the GO/Si3N4 composites. The adequate intermixing of the GO layers and the ceramic powders is achieved in alcohol under sonication followed by blade mixing. The reduction of GO occurs together with the composite densification in SPS, thus avoiding the implementation of additional reduction steps. The materials are studied by X-ray photoelectron and micro-Raman spectroscopy, revealing a high level of recovery of graphene-like domains. The SPS graphene/Si3N4 composites exhibit relatively large electrical conductivity values caused by the presence of reduced graphene oxide (similar to 1 S cm(-1) for similar to 4 vol.%, and similar to 7 S cm-1 for 7 vol.% of reduced-GO). This single-step process also prevents the formation of highly curved graphene sheets during the thermal treatment as the sheets are homogeneously embedded in the ceramic matrix. The uniform distribution of the reduced GO sheets in the composites also produces a noticeable grain refinement of the silicon nitride matrix. (C) 2013 Elsevier Ltd. All rights reserved.
keywords
MECHANICAL-PROPERTIES; RAMAN-SPECTROSCOPY; CARBON NANOTUBES; GRAPHITE OXIDE; MICROSTRUCTURE; NANOCOMPOSITE
subject category
Chemistry; Materials Science
authors
Ramirez, C; Vega-Diaz, SM; Morelos-Gomez, A; Figueiredo, FM; Terrones, M; Osendi, MI; Belmonte, M; Miranzo, P
our authors
Filipe Miguel H Lebre R Figueiredo
Principal Researcheracknowledgements
This work was funded by the Spanish Ministry of Science and Innovation (MICINN), Project number MAT2009-09600. Additional financial support by the project ref I-LINK0119 (CSIC-Shinshu University) is granted. C. R. specially acknowledges the financial support of the JAE-CSIC Fellowship Program. Funding from the Portuguese Foundation for the Science and Technology (FCT) through project PEst-C/CTM/LA0011/2011 is acknowledged by F.M.F. M.T. acknowledges funding from: the Army Research Office MURI grant W911NF-11-1-0362 on Novel Free-Standing 2D Crystalline Materials focusing on Atomic Layers of Nitrides, Oxides, and Sulfides, the U.S. Air Force Office of Scientific Research MURI grant FA9550-12-1-0035, JST-Japan for the Research Center for Exotic Nano Carbons under the Japanese regional Innovation Strategy Program by the Excellence, and the Penn State Center for Nanoscale Science Seed grant on 2-D Layered Materials (DMR-0820404).