New phosphides La5Zn2-xP6 and Ce 5Zn2-xP6 - The n = 4 members of the REZn 2P2·n(REP) series

Lincke H, Nilges T, Pöttgen R

Zusammenfassung

The new phosphides La5Zn2-xP6 and Ce5Zn2-xP6 were synthesized from the rare earth metals, LaZn and CeZn precursor compounds, Zn, and red phosphorous in NaCl/KCl salt fluxes. They crystallize with a new rhombohedral structure type: , Z = 3, a = 422.11(6), c = 6220(1) pm, wR2 = 0.0369, 356 F2 values, 23 variables for La5Zn1.69P6 and a = 417.05(6), c = 6162(1), wR2 = 0.0343, 286 F2 values, 23 variables for Ce5Zn1.75P6. The P3- phosphide anions show an h2c4 stacking sequence in which the RE3+ and Zn2+ cations fill 5/6 and 1/6 of the octahedral and tetrahedral voids in an ordered manner, respectively, leading to a layer of condensed ZnP4 tetrahedra and quintupled layers of condensed REP6 octahedra. The structures of La5Zn2-xP6 and Ce5Zn2-xP6 belong to a larger family of phosphides which are intergrowth variants of CaAl2Si2 and NaCl related slabs according to REZn2P2·n(REP) with n = 4 for the present phosphides.