GeP and (Ge1-xSnx)(P1-yGey) (x ≈ 0.12, y ≈ 0.05): Synthesis, structure, and properties of two-dimensional layered tetrel phosphides

GeP and Sn-doped GeP were synthesized from elements in bismuth and tin flux, respectively. The layered crystal structures of these compounds were characterized by single crystal X-ray diffraction. Both phosphides crystallize in a GaTe structure type in the monoclinic space group C2/m (No. 12) with GeP: 0=15.1948(7) angstrom, b=3.6337(2) angstrom, c=9.1941(4) angstrom, beta=101.239(2)degrees; Ge0.93(3)P0.95(1)Sn0.12(3): a=15.284(9) angstrom, b = 3.622(2) angstrom, c= 9.207(5) angstrom, beta = 101.79(1)degrees. The crystal structure of GeP consists of 2-dimensional GeP layers held together by weak electron lone pair interactions between the phosphorus atoms that confine the layer. Each layer is built of Ge-Ge dumbbells surrounded by a distorted antiprism of phosphorus atoms. Sn-doped GeP has a similar structural motif, but with a significant degree of disorder emphasized by the splitting of all atomic positions. Resistivity measurements together with quantum-chemical calculations reveal semiconducting behavior for the investigated phosphides. (C) 2014 Elsevier Inc. All rights reserved.