1984 Volume 33 Issue 9 Pages 486-490
Impurities (twenty elements) in silicon nitride powder samples were determined by inductively coupled plasma emission spectrometry (ICP-ES). Silicon nitride (0.5 g) was decomposed by 10 ml-hydrofluoric acid and 2 ml-nitric acid in a Teflon pressure vessel at 170°C during 16 h. The obtained sample solution was diluted to 100 ml with distilled water, followed by ICP-ES determination. The spectrometer was equipped with a crossflow platinum nebulizer and a polypropylene spray chamber for the analysis of the sample solutions containing hydrofluoric acid. The recovery of boron was 97101 % in the acid decomposition procedure, suggesting that the leakage of boron from the vessel as boron fluoride was negligibly small. The presence of ammonium ion as matrix component in the sample solution (0.26 %) little affected the emission intensities of the elements. Hexafluorosilicate as matrix component (1.52 %) reduced the emission intensities by 38%, and increased the background levels for several elements of which analytical lines are below 250 nm. Because of this matrix effect, the detection limits of the elementswere somewhat higher in solutions containing hexafluorosilicate than in solutions containing no silicate. The calibration curves for each element were established from a series of solutions containing silicate as a matrix component and were successfully used for the determination of impurities in silicon nitride samples.
