Electron probe microanalysis of nitrogen in glasses and glass ceramics

A homogeneous (phosphate glass) and a heterogeneous (glass ceramic) materia l were chosen to develop a method for electron microprobe analysis of nitro gen in. glasses and glass ceramics. The metaphosphate (50 mole-% P2O5, 25 m ole-% BaO, 25 mole-% Rb2O) base glass and the silicate glass (composition o f the base glass: 6.9 mole-% Al2O3, 21.3 mole-re MEG, 47.3 mole-% SiO2, 5.1 mole-% CaO, 19.4 mole-% AlN) were melted and cooled down to room temperatu re. In a second step, the two materials were nitrided by applying dry NH3 i n a special tube furnace. Up to 5 wt.-% of nitrogen could be introduced. Th e ability of energy dispersive (EDX) as well as wavelength dispersive (WDX) electron probe microanalysis to analyze low contents of light elements in combination with highly concentrated heavy elements was tested both fur gla sses and for glass ceramics. Measuring conditions had to be optimized to ge t reliable analytical results as well as to avoid radiation damage of the g lasses which may occur especially in the case of wavelength dispersive X-ra y analysis. The results were compared with two different analytical methods: inductive coupled plasma analysis and a commercial nitrogen-oxygen-analyzer (the spec imen is decomposed by heating and the released gases are analyzed spectrosc opically (O) and electrically (N)).