Reaction paths via a new transient phase in non-equilibrium hydrogen absorption of LaNi2Co3
Abstract
This study investigated the non-equilibrium hydrogen absorption reaction paths of the AB5-type LaNi2Co3 alloy using time-resolved in situ synchrotron X-ray diffraction. Diffraction data were collected every second for reactions under two hydrogen loading pressures. Hydrogen absorption with a hydrogen loading of 1 MPa rapidly transformed α phase to a transient phase (estimated to be LaNi2Co3H3.1–3.6, named γ∗); this has not previously been observed under equilibrium processes. The γ∗ phase continuously transformed into the γ phase (LaNi2Co3H4.5–5.0), and the β phase (LaNi2Co3H~3.6) was not formed. When 0.18 MPa of hydrogen was loaded, initially, the γ∗ phase appeared, followed by the formation of the β phase, finally transforming into the γ phase. These results indicate that a higher loading pressure promotes the formation of the γ∗ phase and assists its continuous transformation into the γ phase by enhancing the dissolution of hydrogen into the α and γ∗ phases.
- Publication:
-
International Journal of Hydrogen Energy
- Pub Date:
- August 2020
- DOI:
- 10.1016/j.ijhydene.2020.05.237
- Bibcode:
- 2020IJHE...4521655N
- Keywords:
-
- Hydrogen storage alloy;
- Metal hydride;
- In situ time-resolved X-ray diffraction;
- Crystal structure;
- Lattice expansion;
- Non-equilibrium process;
- XRD;
- X-ray diffraction;
- P–C;
- pressure-composition;
- EDX;
- energy-dispersive X-ray spectroscopy;
- ND;
- neutron diffraction;
- SR-XRD;
- synchrotron radiation (SR) XRD;
- Ni-MH;
- nickel-metal hydride