Facile synthesis of metastable Ni-P nanostructured materials by a novel bottom-up strategy

A novel bottom-up strategy combining chimie douce and non-conventional consolidation process to elaborate Ni-P metastable alloy is described here. The chimie douce method consists on the polyol process, modified by the addition of hypophosphite (strong reducing agent). It allows elaborating Ni-P nanopowder. The consolidation of the as-obtained nanoparticles is carried out by Spark Plasma Sintering (SPS). The microstructure of the powder and nanostructured dense sample was studied and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and FTIR spectroscopy. The nanopowder is formed of the metastable Ni-P alloy, with a composition of about 3.44% in phosphorus. Unlike Ni-P alloys prepared by electroless or electrodeposition, the nanoparticles developed show good crystallinity. They have spherical morphologies with a size of about 100 nm and are formed by aggregation of crystallites about 8 nm in diameter. Various analysis techniques showed that SPS treatment induced the transformation of the metastable Ni-P alloy in a two phases: almost pure nickel and a new phase with chemical formula Ni3P. This latter is in form of spherical particles with about 130 nm in diameter, while the nickel grains have a polygonal shape with 330 nm in diameter. (C) 2014 Elsevier Masson SAS. All rights reserved.