Post-hydrogenation structural transformations from KHg2- to Fe2P-type in R(Cu,Ni)2 hydrides (R = Ce, Pr, Nd)

 

Chem. Met. Alloys 3 (2010) 169-176

 

A.B. RIABOV, R.V. DENYS, R. ČERNÝ, I.Yu. ZAVALIY

 

Hydrogenation of orthorhombic KHg2-type R(Cu,Ni)2 pseudobinary intermetallic compounds (R = Ce, Pr, Nd) was found to lead to the formation of an orthorhombic insertion-type hydride, which readily transforms into a hexagonal Fe2P-type hydride. This post-hydrogenation structural transformation can be accelerated by heating in vacuum at 100-120C and is accompanied by release of ¼ of the available hydrogen, as has been confirmed by PND studies. Further heating in vacuum leads to disproportionation of the hydride and recombination with recovery of the orthorhombic R(Cu,Ni)2 compound after complete elimination of hydrogen from the material.

 

 

Repeated hydrogen absorption by Pr(Cu0.75Ni0.25)2 after complete recombination during desorption, and after partial hydrogen release up to 120C.

 

Keywords

Metal hydrides / Crystal structure / X-ray diffraction / Powder neutron diffraction