High-pressure synthesis and low-temperature thermal expansion behavior of homogeneous phosphorus-rich pseudo-binary compound (V0.5Cr0.5)P4

A black phosphorus layered homogeneous phosphorus-rich compound - (V0.5Cr0.5)P4 is synthesized using a large volume press under conditions of P = 5 GPa, 1100 degrees C, and 1 h of heating. (V0.5Cr0.5)P4 has a monoclinic (C2/c) structure with lattice parameters and cell volume of a = 5.2307(3)angstrom, b = 10.861(4)angstrom, c = 5.8253(4)angstrom, beta = 110.784 degrees, and V = 309.41(4)angstrom 3, respectively. The thermal expansion behavior above about 110K has been investigated by low-temperature synchrotron XRD. The coefficient of thermal expansion, alpha, was calculated to be alpha a = 0.57 x 10-5K-1, alpha b = 0.70 x 10-5K-1, alpha c = 0.92 x 10-5K-1, alpha beta = 0.13 x 10-5K-1 and alpha v = 2.10 x 10-5K-1 at 293K. This thermal expansion behavior presents an anisotropic expansion characteristic different from pure black phosphorus due to the V/Cr atom that bonded the black phosphorus layers together.