I started to rummage around in google looking for hydrogen/nickel/lattice
stuff.
(WAY out of my expertise, of course ... I last did any QM/solid state
physics back in the 60's .. but THAT never stopped me ..)
http://72.22.18.215/s_mrs/bin.asp?CID=2653&DID=60819&DOC=FILE.PDF
The Evolution of Short-Range Order in
Ti-Hf-Ni Alloys with Hydrogenation
Anne
Sadoc1,2
, Van T.
Huett3
, K. F.
Kelton3
CONCLUSIONS
This represents the first
systematic study of the effect of hydrogenation on the short-range order
of the Ti-Hf-Ni
alloys. The influence of hydrogen on the local structure of Ti-Hf-Ni
alloys, 3/2 approximant and amorphous alloys,
was investigated using extended X-ray absorption fine structure. First,
the same local icosahedral order was found to
exist in the 3/2 Ti-Hf-Ni alloy and in the Ti-Zr-Ni alloys, icosahedral
quasicrystal or 1/1 approximant. Secondly,
with an increasing hydrogen-to-metal ratio from 0 to 1.7, a general
increase of all the mean first distances was found
in 3/2 Ti-Hf-Ni, except for the Ni-Hf (Hf-Ni) one, which was found to
decrease. The increase of the Hf-Ti correlation
together with the decrease of the Hf-Ni one results in a remarkable
inversion of the atomic subshells of titanium and
nickel around hafnium atoms for a H/M ratio around 1.2. This clearly
indicates that hydrogen loading induced
distortions in the structure. Some hydrogen-hafnium interactions could
bring hafnium atoms closer to nickel atoms.
The perturbation of the lattice, induced by hydrogenation, is a maximum
around the Ti and Hf atoms, which suggests
that hydrogen atoms sit preferentially near titanium and hafnium atoms,
confirming previous results of studies of
hydrogenated Ti-Zr-Ni alloys.
(Hafnium was discussed back at
http://www.mail-archive.com/[email protected]/msg42990.html --
Feb 24, 2011)
