Silicon nitride nanodisperse powder, synthesised by vapous phase reaction in RF thermal plasma. Samples were aged in air of 80 % relative humidity and also in dry air for various length of time.
This powder consisted of nearly spherical particles with 400 Å average diameter. The structure of the particles was assumed as follows: a core of Si3N4 is surrounded by a SiO2 layer and a carbonaceous contaminant layer.
Intensity ratios of the characteristic lines (Si2p, N1s, O1s, C1s) were calculated using the Layers-on-Sphere model and fitted to the measured values. Results clearly demonstrate the fast development of the oxidised layer in the humid atmosphere while the thickness of the contaminant layer is practically unchanged.
Increasing of the thickness of the SiO2 layer on the Si3N4 particles during long term ageing
J. Szépvölgyi, I. Mohai, J. Gubicza:
Atmospheric Ageing of Nanodisperse Silicon Nitride Powders.
J. Mat. Chem. 11, 859 (2001).