RESUMEN
Mg2Ni-type Mg2Ni1-xCox (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg2Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio () of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio () from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10-11 to 3.88 × 10-11 cm²/s and the limiting current density IL from 150.9 to 887.4 mA/g.
RESUMEN
Ce(1-x)(Fe(0.5)La(0.5))xO(2-delta) solid solutions were obtained via hydrothermal method. The structure of the solid solutions and the cell parameters were characterized by XRD analysis technique, the electron transition properties and doping effectswere measured by UV-Vis diffraction spectrum and Raman spectrum technique. XRD results showed that Ce(1-x)(Fe(0.5)La(0.5))xO(2-delta) id solutions exhibited cubic fluorite structure till the doping content increased to 0.30. Tiny Fe2O3 phase was observed when x = 0.30. The particle size was kept nanoscaled, and location of different kind of doping ions in CeO2 lattice was discussed. By increasing the doping content, the cell parameter was kept increasing gradually till x = 0.18, then it remained almost constant. The UV-Vis diffraction spectrum analysis showed that the absorption threshold edge redshifted, the band gap energy decreased with increasing the doping content. The valence of Fe ions in the lattice of CeO2 was +3. The F2g Raman mode also showed a downshift, and the peak gradually became broader, which further proved the influence of the dopant.