EXPLORATION OF THE INTERSTITIAL DERIVATIVES OF LA5PB3 (MN3SI3-TYPE)

Powder sintering reactions of the elements or of appropriate binary ph ases in welded Ta containers have resulted in the single phase synthes es of 17 La5Pb3Z derivatives of La5Pb3 with stuffed Mn5Si3-type struct ures (P6(3)/mcm), namely, Z = B(x), C(x), P, S, Cl, As, Se, Sb, Cr, Mn , Fe, Co, Ni, Cu, Zn, Ru, and Ag. (Z = N, O form a Cr5B3-type derivati ve.) Possible x values for B and C are consistent with, but not proof of, Zintl phase characteristics. La5Pb3 was shown to be a line phase, while the reported binary LA4P3 (anti-Th3P4) was not found. The volume changes observed on incorporation of Z into La5Pb3 are the smallest f ound in this sort of system except for chloride in the even more weakl y bound alkaline-earth-metal-pnictide analogues. (C) 1994 Academic Pre ss, Inc.