REACTION OF SAMARIUM WITH HYDROGEN AND NITROGEN SAMARIUM OXIDES

The reaction characteristics between Sm metal and H-2 or N2 gas have been studied by means of isochorothermal analysis and X-ray diffraction. Samarium was found to react with hydrogen forming SmH2+x (0 less-than-or-equal-to x less-than-or-equal-to 0.63). The reaction is very abrupt, exothermic and takes place at a temperature of between 300 and 525-degrees-C depending on the initial size, surface contamination and surface structural defects of the samarium metal. Sm hydrides are partially decomposed into b.c.c. Sm2O3 under ambient conditions. The reaction of Samarium with N2 initiates at about 600-degrees-C and proceeds very slowly forming SmN. SmN hydrolyzes in the presence of atmospheric moisture to form b.c.c. Sm2O3, hex-Sm(OH)3 and NH3. Sm oxide surface layers containing f.c.c. SmO, b.c.c. Sm2O3 and monoclinic Sm2O3 were found to form upon heat treatment of Sm metal under vacuum or argon gas flow.