 Numerous crystalline binary compounds are known for samarium and one of the group @-@ 4 , 5 or 6 element X , where X is Si , Ge , Sn , Pb , Sb or Te , and metallic alloys of samarium form another large group . They are all prepared by annealing mixed powders of the corresponding elements . Many of the resulting compounds are non @-@ stoichiometric and have nominal compositions SmaXb , where the b / a ratio varies between 0 @.@ 5 and 3 . 
