In-situ reaction synthesis of pure bulk gadolinium dihydride materials

A novel reaction in-situ synthesis technique was developed for preparing pure bulk polycrystalline Gd dihydride materials by combination of the hydrogen plasma metal reaction (HPMR) and spark plasma sintering (SPS). The nanoparticles of Gd hydrides were firstly prepared by HPMR. SPS process was then introduced to synthesize the bulk GdH2 materials from the nanoparticles. The pure consolidated bulk GdH2 materials were achieved after sintering at temperature 750–900 °C with a pressure of 50 MPa in a vacuum atmosphere. The GdH2 phase with face centered cubic (FCC) and GdH3 phase with hexagonal condensed packed (HCP) exist in the nanoparticles, and the consolidated bulk, however, is a single phase GdH2 with FCC. Subsequent annealing process can make the bulk GdH2 material transform back to pure HCP Gd. Microstructure analysis reveals that the consolidated bulk material exhibits a good microstructure. These results indicate that the HPMR–SPS process is an effective method for the synthesizing bulk GdH2 materials.