Interactions of hydrogen with Tb3Ni6M2 (M= Al,Ga, or Si) alloys with structures of Ce3Ni6Si2 type

Summary A crystallochemical analysis has been performed on the structures of Tb₃Ni₆M₂ (M = Al, Ga, Si), which crystallize in the Ce₃Ni₆Si₂ structure type, as they are potential hydrogen absorbers. There are seven types of cavity suitable for hydrogen atoms. When the Tb₃Ni₆M₂ intermetallides interact with hydrogen, hydride phases are formed that contain 0.32-0.95 mass % H and which decompose completely in the range 20–300°C. The hydrogen contents in the hydrides and the thermal stabilities decrease in the aluminide-gallide-silicide sequence. Hydrogenation produces isotropic expansion in the initial body-centered cubic structures. Neutron diffraction indicates that the deuterium atoms in Tb₃Ni₆Al₂D_6.5 occupy the Tb₃Al, TbNi₃, and Ni₄ cavities.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 4, pp. 22–25, July–August, 1991.