Halocarbon-assisted slurry vaporization in inductively coupled plasma atomic emission spectrometry for the analysis of silicon nitride powder

Abstract

A conventional Babington-type nebulizer was applied for introduction of samples in the form of solutions and slurries (1% m/m) produced from a finely dispersed silicon nitride (Si₃N₄) powder (mean particle size 0.54 µm). Calibration with solution standards for the slurry method resulted in 20–40% negative deviations in the results for impurities of Al, Fe, Ca, Mg and Ti compared with the dissolution-based analysis. The addition of Freon-12 (CCl₂F₂), as a possible halogenation agent, to the plasma resulted in decreased negative deviations by factors of between 1.2 and 2.8, which suggests that the degree of evaporation of the slurry particles was increased by halogenation. The fact that the negative deviations could not be completely eliminated could perhaps be explained by a difference in the efficiency of nebulization (as the sample introduction process) for the solutions and the slurries, which applies rigorously to the present sample type and nebulizer system. With the introduction of Freon, no degradation in the linearity of the analytical curves was found in contrast to earlier observation by other workers. The line-to-background intensity ratios (wavelength >220 nm) were not decreased at the rate of halocarbon introduction eventually used.