Direct determination of trace impurities in high-purity silicon nitride by axial viewed inductively coupled plasma optical emission spectrometry using a slurry nebulization technique

Abstract

The dispersive effect of polyacrylate amine (NH₄PAA) upon suspensions of silicon nitride (Si₃N₄) is considered. Slurry introduction for axial inductively coupled plasma optical emission spectrometry determination of Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni and Ti in powdered Si₃N₄ has also been investigated. Characterization by zeta potential measurement and slurry stability measurements shows that NH₄PAA is a good dispersant for the preparation of Si₃N₄ suspensions. The optimal concentration of NH₄PAA was 0.8 wt% for μm-sized Si₃N₄ and 1.2 wt% for nm-sized Si₃N₄. The analytical results obtained using nm- and μm-sized Si₃N₄ by slurry introduction were in good accordance with results obtained by the high-pressure acid deposition method, thus verifying that calibration curves could be established using aqueous standards. By introducing a low amount of contamination in the sample preparation, an accurate result is obtained for the detection of contamination-risk elements such as K and Na, which cannot be accurately determined by the high-pressure acid deposition method. The limits of detection, which are in the range of 8–250 ng g⁻¹, were shown to be superior to those of the conventional nebulization technique with ICP-OES or ICP-MS.