Potential of a microwave boosted glow discharge source for the analysis of silicon carbide powder

The microwave boosted glow discharge source has been investigated for its potential to analyse ceramic powders by atomic emission spectrometry. SiC was used as an example. Electrically conducting samples were prepared by mixing the SiC-powder with copper powder and compressing the mixture to pellets. Prior to the measurement the samples were heated to a temperature of 200 degrees C for 2 h to release molecular species adsorbed on the surface of the powders and to reduce the intensity of molecular bands in the spectrum. The discharge was operated in argon as the plasma gas and boosted with 40 W microwave power. Argon pressure and anode current were optimized to give the best line-to-background ratios. Crater shapes and erosion rates have been measured. The erosion rates were found to be much lower in the pellets (23 nm s(-1)) than in bulk copper samples (63 nm s(-1)). Background equivalent concentrations, measured for six elements in the pellets, are in the range of 0.1-6 mu g/g.