In-situ crystallization study of amorphous Ni-P nanoparticles with high P content

The crystallization behavior of amorphous Ni-P nanoparticles produced by liquid pulsed-discharge was studied by using in situ high temperature XRD at beamline 4B9A of Beijing Synchrotron Radiation Facility. Transmission electron microscope (TEM) was used to observe the morphology and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) was used to analyze the chemical composition of the as-prepared Ni-P nanoparticles. TEM results show that the average size of the as-prepared nanoparticles is about 13.5 nm. ICP-AES identifies the Ni-P nanoparticles contain 13.16 wt. % (21.85 at. %) of P and 86.84 wt. % (78.15% at. %) of Ni. Eight XRD patterns were, respectively, collected at 300, 373, 473, 573, 673, 773, 873 and 973K under low-vacuum condition (0.1 Pa). XRD results show that the as-prepared Ni-P nanoparticles are amorphous, no peaks of crystalline phases can be observed until 573K. Afterwards, the crystallization of the amorphous phase undergoes the formation and decomposition of some metastable phases. Finally, the obtained stable phases are the bct Ni₃P and fcc Ni cryatalline phases. Both are randomly distributed in the sample. The crystallization mechanisms of the as-prepared amorphous Ni-P nanoparticles has also been discussed at the end of this paper.