Temperature and concentration dependence of hydrogen site occupancy in several rare-earth dihydrides

Neutron inelastic scattering and diffraction techniques were used to study the hydrogen site distribution in several rare earth dihydrides as a function of temperature and concentration. For Y, La, and Ce the fraction of hydrogen on octahedral sites is approximately a constant from 15K to 200K followed by a decrease with increasing temperature. A model is presented which qualitatively explains this behavior