Significant improvement in the dehydriding properties of perovskite hydrides, NaMgH3, by doping with K2TiF6

In this study, perovskite hydrides (NaMgH3) were synthesized in the presence and absence of a dopant, e.g., K2TiF6, by high-energy ball milling. Clear lattice distortion was observed in K2TiF6-doped NaMgH3 as compared to pristine NaMgH3. The doped sample exhibited better dehydriding properties, and the onset desorption temperature significantly decreased from 580 K to 328 K. The maximum amount of desorbed hydrogen was approximately 3.8 wt% at 638 K, and approximately 90% of hydrogen was desorbed within 20 min. Differential scanning calorimetry results indicated that the activation energy for the two steps in the decomposition of NaMgH3 decreases by doping with K2TiF6. This result suggested that the lattice distortion and low decomposition energy of the NaMgH3 phase, caused by the introduction of the K2TiF6 dopant, result in improved dehydriding properties for NaMgH3.