Electronic Noise in Silicon Nitride Ceramics Doped by Carbon Allotropes

摘要

The electric conduction and low-frequency noise were investigated in silicon nitride-based ceramics doped with different carbon allotropes as multi-wall carbon nanotubes, black carbon and graphite powder. The electric conduction was found unstable in time. This instability does not depend on the atmosphere and on the possible variation of the temperature. The noise spectra show 1/f character, however the magnitude of the noise differ for the different dopants, and strongly depends on the pressure of sintering. The comparison of the resistance values and the noise magnitudes suggest that the carbon dopants form percolation networks. The carbon is distributed most likely at the surface of the ceramic particles like the Swiss-Cheese model.