Determination of the nitrogen content of uranium mononitride by alkaline fusion and ammonia distillation
A fusion procedure for determining the nitrogen content of uranium mononitride materials has been developed. Recovery of 96·7 per cent. of the theoretical nitrogen was demonstrated with a sodium hydroxide melt containing 20 per cent. w/w of sodium carbonate at a fusion temperature of 500° to 525° C.
The uranium mononitride reference used contained 600 p.p.m. of oxygen, 200 p.p.m. of carbon and less than 500 p.p.m. of halide impurities. Fifteen analyses of a stoicheiometric mononitride reference gave a nitrogen content of 5·37 per cent. w/w, average deviation of ±0·04 and standard deviation of ±0·06. Analyses of ammonium iron(III) sulphate and ammonium chloride for nitrogen by the alkaline fusion technique gave nitrogen recoveries of 98·9 and 100·5 per cent., respectively. Fusions carried out at temperatures below 475° C were not completely digested. Also, fusion analyses at temperatures above 575° C gave slightly lower nitrogen values because of partial decomposition of the ammonia.