Crystal and electronic structure of La3Zn2-xP4 - New phosphide with isolated P3- species

Lincke H, Nilges T, Johrendt D, Pöttgen R

Zusammenfassung

The new phosphide La3Zn2-xP4 was synthesized from lanthanum, LaZn and red phosphorous in a NaCl/KCl halide flux at 1120K. La3Zn2-xP4 crystallizes with a new structure type: R3¯m, a=418.72(7), c=4143.7(1)pm, wR2=0.0577, 1061 F2 values for La3Zn1.75P4 and a=418.99(6), c=4157.1(8)pm, wR2=0.0485, 337 F2 values for La3Zn1.88P4 with 17 variables per refinement. The P3- phosphide anions show an hhcc stacking sequence, similar to the structures of Mg3In and PuGa3. The Zn2+ and La3+ cations fill 1/4 and 3/4 of the tetrahedral and octahedral voids, respectively, in an ordered manner, leading to a layer of ZnP4 tetrahedra and triple layers of LaP6 octahedra. DFT band structural calculations verify that the lower zinc occupation stabilizes the structure close to an electron precise composition.