The formation enthalpy value of Mg₂Ni(Fe)H₄ in the Mg–Ni(Fe)–H sample and the ones of Mg₂NiH₄ reported in the literatures^25,27–29.

Formation (ΔH) (kJ mol−1 H2)	Reference
−53.1	This work
−67.5	25
−64.6	27
−66.3	28
−63.2	29