The index of refraction of PuO2 made by thermal decomposition of PU(C2O2, 6H2O gradually increases from a value < 1.9 to 2.40 as the decomposition temperature is increased from 150 degree to l000 degree C. This change in refractive index parallels a gradual change in the x-ray diffraction pattern from weak, diffuse lines for PuO2 ignited at 150° to sharp, well resolved lines for PuO2 ignited at 1000°C. Similar results are observed for PuO2 made by thermal decomposition of Pu2(C2O4)3*11H2O. The refractive index of PuO2 made from Pu metal at 170°C is 2.40 and is not affected by further ignition at higher temperatures, although crystal growth does occur. The rate of solution of PuO2 in an HCl-KI solution is greatest for samples prepared at low temperatures and decreases markedly for oxides ignited at higher temperatures. These observations hive been interpreted to mean that ignition at higher temperatures causes a gradual perfection of the originally highly distorted and impurity-containing PuO2 lattice obtained by low temperature decomposition of the oxalates and promotes the slow growth of crystallites. Both factors decrease the reactivity of the PuO2.

This technical report summarizes the work which has been done to date on the preparation of magnesium hydride and the attempted preparation of beryllium hydride. Although pure beryllium hydride has not yet been made, the work is continuing, and this report indicates which phases are thought to be worth further work.

The index of refraction of PuO2 made by thermal decomposition of PU(C2O2, 6H2O gradually increases from a value < 1.9 to 2.40 as the decomposition temperature is increased from 150 degree to l000 degree C. This change in refractive index parallels a gradual change in the x-ray diffraction pattern from weak, diffuse lines for PuO2 ignited at 150° to sharp, well resolved lines for PuO2 ignited at 1000°C. Similar results are observed for PuO2 made by thermal decomposition of Pu2(C2O4)3*11H2O. The refractive index of PuO2 made from Pu metal at 170°C is 2.40 and is not affected by further ignition at higher temperatures, although crystal growth does occur. The rate of solution of PuO2 in an HCl-KI solution is greatest for samples prepared at low temperatures and decreases markedly for oxides ignited at higher temperatures. These observations hive been interpreted to mean that ignition at higher temperatures causes a gradual perfection of the originally highly distorted and impurity-containing PuO2 lattice obtained by low temperature decomposition of the oxalates and promotes the slow growth of crystallites. Both factors decrease the reactivity of the PuO2.