Neutron activation analysis of impurities in gallium phosphide

The present study was developed to the special case of gallium phosphide. The possibilities of non-destructive analysis of long-lived element (cobalt, iron, antimony, scandium, zinc...) were investigated first. After a 20 decay period, the gallium activity (gallium 72: half-life 14.7 hours) is negligible, but that of phosphorus (phosphorus 32: half-life 14.3 days) is troublesome because of its bremsstrahlung. However some elements (cobalt, iron, antimony, scandium, silver) can be determined by gamma spectrometry with a lead screen placed between the source and the detector. To extend this method to the determination of medium-life elements, different methods of radiochemical separation were developed. They are based on the precipitation of Au, Ag, Cu, As and Sb in the form of sulfides, the separation of Ga, Co, Fe and Zn on Dowex resin and the elimination of P on hydrated alumina. Finally this method enables the quantitative analysis of 14 elements (Ag, As, Au, Ba, Co, Cu, Fe, Ir, Na, Rb, Sb, Sc, Zn)