Crystal structure and physical properties of AePd1-xP1+x (Ae = Ca, Sr)

Abstract

We report the discovery of two new compounds AePd1-xP1+x (Ae = Ca, Sr) crystallized in different hexagonal structures. Single crystals of AePd1-xP1+x (Ae = Ca, Sr) are obtained using the Bi-flux method. Crystallographic analysis by both powder and single crystal X-ray diffraction shows that CaPd1-xP1+x crystallizes in a non-centrosymmetric hexagonal structure with the space group P-6m2 (No.187) and lattice parameters a = b = 4.0391(9) Å and c = 4.1026(9) Å, while SrPd1-xP1+x forms a centrosymmetric hexagonal structure with the space group P63/mmc (No. 194) and lattice parameters a = b = 4.102(2) Å and c = 8.713(4) Å. In both compounds, Pd and P atoms mix in the honeycomb layer with a higher amount of P. The electronic structure calculations show that the mixture of Pd and P atoms in the honeycomb network is critical to stabilize the crystal structures. AePd1-xP1+x (Ae = Ca, Sr) are diamagnetic metals confirmed by the magnetic susceptibility, electrical resistivity and specific heat.