Activation energy study on nanostructured niobium substituted Mg<sub>2</sub>Ni intermetallic alloy for hydrogen storage application
K. S. Nivedhitha, R. Venkatesh, N. R. Banapurmath
Abstract
Abstract The magnesium-based metallic alloys have been exhibited to be the improved hydrogen storage materials. In the present investigation, a nanostructured Mg 67 Ni 33 and Niobium substituted intermetallic compound was prepared by a high-energy ball milling technique for hydrogen storage application. Niobium substitution on the pure crystalline intermetallic compound changed the structure of the crystalline to semi-amorphous as well as changed the interplanar spacing after 30 h of milling. Furthermore, the effect of Nb substitution on the inter-planar shift and its corresponding implications on lattice strain, crystallite size, and unit cell volume of the Mg 2 Ni compound were also discussed. Transmission electron microscope studies confirm the particle size was reduced to less than 100 nm for 30 h of milling. However, SEM images confirm the agglomeration of these nanoparticles and form spherical particles of size around 3–5 μ m. XRD and EDS authenticate the presence of oxides. Kissinger’s analysis confirmed that Mg 2 Ni powder exhibited lower activation energy of 64.101 kJ mol −1 than niobium-substituted alloy powders. The hydrogen charge and discharge potential of these compounds are discussed in detail.