An investigation of chemically deposited Ni-P alloys by EXAFS and XRD

Five samples of chemically desposited Ni-P amorphous alloys were prepared and investigated. In these amorphous alloys there are Ni-P atom groups in which phosphorus and nickel are connected with strong interaction. Nickel atoms and Ni-P groups are deposited in a random manner on the surface of matrix and a quasilayer structure is formed. The spacing between two layers in alloys resembles that in (111) plane in the nickel crystal. Therefore there is a peak at the same position of 2θ=44.4° as that of the (111) reflection of crystalline nickel in the X-ray powder diffraction pattern of alloys. However, the dimension of Ni-P groups is different from that of a nickel atom and the atomic arrangement in the layer is in disorder. These result in the space change and there is a distribution of spacing around the average. As a consequence of distribution of spacings, the peak at 2θ=44.4° is broadened and enhanced as the amount of P increases.