ILa5Pb3, hexagonal, P6ì/mcm (no. 193), a = 9.736(1) A, c = 6.947(1) A, V= 570.3 Â 3 , Z= 2, Rp(F) = 0.029, wRrerfF 2 ) = 0.068, T= 293 K. Source of materialLasPbal is prepared by heating a mixture of Lab, La and Pb (molar ratio 1:14:9) under Ar atmosphere in sealed Ta capsules at 1220 K for 5 days, yielding a pure phase. LasPbal forms silver colored needles sensitive to moisture. DiscussionThe crystal structure of LasPbjI is derived from the Nowotny phases H-