Crystal structure of α‴-(Zn1−xCdx)3As2 (x = 0.26)

Single crystals of the α‴-phase of (Zn1−xCdx)3As2 solid solution (x = 0.26) have been prepared and investigated by X-ray diffraction analysis. The tetragonal unit-cell parameters are found to be a = b = 8.5377(2) Å, c = 24.0666(9) Å, sp. gr. I41/amd, Z = 16. Zn and Cd atoms in the crystal statistically occupy three symmetrically independent positions in the mirror planes and are tetrahedrally coordinated by arsenic atoms. (Zn,Cd) tetrahedra share edges to form a three-dimensional structure framework. The α‴-phase is geometrically related to the fluorite structure. The character of arrangement of tetrahedral vacancies in fluorite-like unit cells is revealed. Chains of tetrahedral vacancies form microchannels oriented parallel the a and b axes, which pierce the three-dimensional structure framework at different levels along the c axis. The structure of α″-Cd3As2 crystals is found to be similar to that of α‴-(Zn0.74Cd0.26)3As2