Hydrogen absorption characteristics in the Tb<inf>1-x</inf>Zr<inf>x</inf>Fe<inf>3</inf> (x=0.1, 0.2, 0.3) system

The hydrogen absorption pressure-composition-isotherms of the PuNi3 type rhombohedral Tb1-xZrxFe3 (x=0.1, 0.2, 0.3) alloys are investigated by Sievert's apparatus, in the temperature and pressure ranges 75≤T(°C)≤150 and 0.1≤P(bar)≤25, respectively, with a view to study the dependence of hydrogen solubility and the plateau pressure on Zr content. The P-C isotherms show the presence of a single plateau region in the temperature and pressure ranges studied and it is found that the plateau pressure at any given temperature increases with increase of Zr content along with a reduction in the hydrogen capacity. The absorption of hydrogen is accompanied by a maximum of 17.4% expansion in the unit cell volume of the host material without any change in PuNi3 type structure as evidenced by the X-ray diffraction studies on the alloy-hydrides. The presence of single and two phase regions as seen in the P-C isotherms are confirmed from the powder X-ray diffractogram of the alloy-hydrides with appropriate hydrogen concentration. The powder X-ray diffractograms on the alloy-hydrides with maximum hydrogen concentration further show the absence of hydrogen induced amorphization (H1A) upon hydrogenation.