A cation-excess (Ni,Mn) ferrite Ni0.52Mn0.51Fe2.05O4.0 with a single p
hase was synthesized by heating the mixture of corresponding metal sal
ts and oxide in 5% O-2/75% CO2/20% N-2 gas mixture for 18h at 1100C. I
t could be thermochemically activated to form a cation-excess ferrite
Ni0.52(1+delta)Mn0.51(1+delta)Fe2.05(1+delta)O-4.0 in N-2 gas at eleva
ted temperature: The ( value was 0.031 at 1100C. The activated (Ni,Mn)
ferrite was reacted with water to form H-2 gas at 700C. The process w
as reversible and could be carried out repeatedly.