TDPAC study of the ZrCo-hydrogen system

The properties of the ZrCo-hydrogen system as a function of composition ratio H/ZrCo were investigated by combining TDPAC and X-ray diffraction techniques with the full potential linearized augmented plane wave (LAPW) band structure calculations. It was found that during hydrogenation ZrCo transferred directly into ZrCoH3 and no transition phase existed. The z component Vzz of the efg and the asymmetry parameter η at the Zr and Co sites were calculated for ZrCoH3 by using the structure parameters of Zr and Co, obtained in the present work, combined with the hydrogen structure parameters obtained from neutron diffraction on ZrNiH3. The calculations are in good agreement with the measured values for Vzz and η. This agreement is consistent with the proposed 4c and 8f interstitial sites occupancy of the hydrogen atoms in ZrCoH3.