Synthesis, crystal structures, and physical properties of the new Zintl phases A21Zn4Pn18 (A=Ca, Eu; Pn=As, Sb)-Versatile arrangements of [ZnPn4] tetrahedra

The four new Zintl phases-Ca21Zn4As18, Ca21Zn4Sb18, Eu21Zn4As18, and Eu21Zn4Sb18-crystallize in two structure types, showing the versatility in the arrangements of ZnAs4 and ZnSb4 tetrahedra.222