Synthesis, structural characterization, electronic structure, and magnetic properties of the Zintl phase Eu10Cd6Bi12.

A new transition-metal-containing Zintl phase, Eu(10)Cd(6)Bi(12), was synthesized by combining the elements in excess molten Cd. Single-crystal X-ray diffraction studies indicated that this compound crystallizes in the orthorhombic space group Cmmm (No. 65) with a=7.840(2), b=24.060(7), and c=4.7809(14) A. The crystal structure of Eu(10)Cd(6)Bi(12) can be viewed as a stacking of a series of [Cd(6)Bi(12)] double layers, which are arranged alternately along the b axial direction. The layers are composed of corner- and edge-shared CdBi(4) tetrahedra, a common feature in the crystal chemistry of many transition-metal Zintl phases. Electronic-band-structure calculations confirm the closed-shell configuration of all constituent elements and corroborate the electron count inferred by the Zintl formalism, that is, [Eu(2+)](10)[Cd(2+)](6)[Bi(3-)](8)[Bi(2-)](4). Magnetic-susceptibility measurements confirm the divalency of europium and show the existence of a long-range antiferromagnetic order of the Eu spins below 12.3 K.