Boron nitride trace analysis

The boron nitride obtained in this study was characterized by infrared spectroscopy, powder x-ray diffractometry and transmission electron microscopy. Trace elemental analyses were also performed by energy dispersive x-ray analysis and carbon arc emission spectroscopy. Representative spectra are displayed in Figures 2-4. 

The preparation of boron nitride from orthoboric acid and urea is described by T. E. O Connor [81]. Special measures are required to remove the last traces of boric oxide commercial preparations are likely to be significantly contaminated with 820 and water. Deacon and Goodman [11] found a small loss of volatiles at 373-423 K from boron nitride subjected to thermogravimetric analysis in air and a large increase in weight at 1123-1173 K, which is the temperature range of the active oxidation of BN to B2O2. 

With the aid of an internal standard, fluctuations in sample delivery in particular and, to a certain extent, changes in excitation conditions can also be compensated for. To appreciate the full benefit of internal standardization, the intensities of the analytical line and the internal standard line, and in trace determinations also of the spectral background near the analytical line, should be measured simultaneously, which can easily be done in the case of a CCD spectrometer. The full analytical precision of ICP-OES can thus be obtained. This can be demonstrated by the determination of the main components, as is required in stoichiometric determinations of advanced ceramics. After optimizing the sample dissolution procedure in the case of silicon-boron-carbo-nitride, which can be speeded up by microwave-assisted decomposition with acids [455], silicon at the 60% level could be determined with a sequential spectrometer with an absolute error of analysis (standard deviation including replicated analyses as well as decompositions) of 1% or better. 

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