Flux growth and structure of two compounds with the EuIn2P2 structure type, AIn2P2 (A = Ca and Sr), and a new structure type, BaIn2P2

Author(s): Rauscher, JF; Condron, CL; Beault, T; Kauzlarich, SM; Jensen, N; Klavins, P; Maquilon, S; Fisk, Z; Olmstead, MM | Abstract: Single crystals of the new Zintl phases AIn2P2[A = Ca (calcium indium phosphide), Sr (strontium indium phosphide) and Ba (barium indium phosphide)] have been synthesized from a reactive indium flux. CaIn2P2and SrIn2P2are isostructural with EuIn2P2and crystallize in the space group P63/mmc. The alkaline earth cations A are located at a site with m symmetry; In and P are located at sites with 3m symmetry. The structure type consists of layers of A2+cations separated by [In2P2]2-anions that contain [In2P6] eclipsed ethane-like units that are further connected by shared P atoms. This yields a double layer of six-membered rings in which the In - In bonds are parallel to the c axis and to one another. BaIn2P2crystallizes in a new structure type in the space group P21/m with Z = 4, with all atoms residing on sites of mirror symmetry. The structure contains layers of Ba2+cations separated by [In2P2]2-layers of staggered [In2P6] units that form a mixture of four-, five- and six-membered rings. As a consequence of this more complicated layered structure, both the steric and electronic requirements of the large Ba2+cation are met. © 2009 International Union of Crystallography.