Graphene nanoplatelet/silicon nitride composites with high electrical conductivity


Silicon nitride (Si3N4) processed with up to 25 vol.% of graphene nanoplatelets (GNPs) gives conductive composites with the highest electrical conductivity (40 Scm(-1)) reported for these ceramics with added conductive particles. During compaction and pressure-assisted densification of the composites in the spark plasma sintering (SPS), a preferred orientation of GNPs occurs. Consequently, the electrical conductivity measured along the direction perpendicular to the SPS pressing axis is more than one order of magnitude higher than the one measured along the parallel direction. Percolation in the composites is observed for 7-9 vol.% of GNPs, depending on the measuring direction, perpendicular or parallel to the pressing axis. Different conduction mechanisms are apparent for the two orthogonal orientations. Charge transport along the direction defined by the graphene ab-plane (perpendicular direction) may be explained by a two dimensional variable range hopping mechanism, whereas conduction in the parallel direction shows a more complex behavior, with a metallic-type transition (d sigma/dT < 0) for high GNP contents. A thin amorphous layer was identified at the Si3N4/GNPs interface that may affect the conduction for the parallel configuration. (C) 2012 Elsevier Ltd. All rights reserved.



subject category

Chemistry; Materials Science


Ramirez, C; Figueiredo, FM; Miranzo, P; Poza, P; Osendi, MI

our authors


This work was funded by the Spanish Ministry of Science and Innovation (MICINN) under Project number MAT2009-09600, and the Portuguese Foundation for the Science and Technology (FCT, projects Pest-C/CTM/LA0011/2011 and PTDC/CTM-CER/109843/2009). C. Ramirez acknowledges the financial support of the JAE-CSIC fellowship Program.

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