Determination of oxygen in silicon nitride by X-ray fluorescence analysis

A possibility of quantitative analysis of oxygen by X-ray fluorescence spectroscopy was studied for silicon nitride powder. An X-ray spectrometer used was composed of a sealed rhodium target tube (3 kW), an analysing crystal of thallium acid phtalate (2 d= 25.9 Å) and a gasflow proportional counter as a detector for OKα line with an 1 μm polypropylene film window with the operating condition of X-ray tube at large current under low potential (35 kV-80 mA), intensities of the OKα peak (2θ= 132.90 °) and those of the background (2θ= 128.00°) from the briquette samples were measured separately for 100 s and the net OKα intensity was obtained by subtracting the background from the peak intensity. Typical counting rate of the OKα line was 45 counts/s for the sample of 4.28 % oxygen content. A calibration curve was constructed from silicon nitride powder samples of known oxygen contents that were obtained by the graphite capsule-nitrogen fusion method using tin as a bath metal. The result showed a favorable linearity over the oxygen concentration range of (0.14.3) %. Ten kinds of samples were determined by use of the calibration curve. Analytical results agreed closely with that obtained by the fusion method, and the coefficient of variation was 2.3 % for seven samples of 3.57 % oxygen content.