Ternary phosphides Ce3Zn2−xP4 and Ce4Zn2−xP5 – Stacking variants of CeP6 octahedra and ZnP4 tetrahedra

New ternary phosphides Ce3Zn2−xP4 and Ce4Zn2−xP5 were synthesized from intermetallic precursors CeZn and CeZn3, cerium, and phosphorus in equimolar NaCl/KCl fluxes. The structures were refined on the basis of single crystal X-ray diffractometer data: La3Zn2P4 type, R3¯m, a = 414.1(1), c = 4102(1) pm, wR2 = 0.0378, 288 F2 values, 17 variables for Ce3Zn1.82P4 and P3¯m1, a = 415.9(1), c = 1710.5(6) pm, wR2 = 0.0408, 361 F2 values, 20 variables for Ce4Zn1.80P5 (new structure type). The phosphorus atoms in both structures form close-packed layers with stacking sequences (hhcc)3 for Ce3Zn1.82P4 and hhccc for Ce4Zn1.80P5. The cerium and zinc atoms fill octahedral and tetrahedral voids in the close-packed phosphide substructures with Ce–P and Zn–P distances in the ranges 291–302 and 249–251 pm. Temperature-dependent susceptibility measurements of Ce4Zn1.80P5 show an experimental magnetic moment of 2.55(1) μB/Ce atom, indicating pure trivalent cerium. Ce4Zn1.80P5 orders antiferromagnetically at 3.5(1) K.

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