Hydrogen absorption characteristics in the Tb1-xZrxFe3 (x = 0.1, 0.2, 0.3)system

The hydrogen absorption pressure-composition-isotherms of the PuNi3 type rh ombohedral Tb1-xZrxFe3 (x=0.1, 0.2, 0.3) alloys are investigated by Sievert 's apparatus, in the temperature and pressure ranges 75 less than or equal to T(degrees C)less than or equal to 150 and 0.1 less than or equal to P(ba r)less than or equal to 25, respectively, with a view to study the dependen ce of hydrogen solubility and the plateau pressure on Zr content. The P-C i sotherms show the presence of a single plateau region in the temperature an d pressure ranges studied and it is found that the plateau pressure at any given temperature increases with increase of Zr content along with a reduct ion 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 w ithout any change in PuNi3 type structure as evidenced by the X-ray diffrac tion studies on the alloy- hydrides. The presence of single and two phase r egions as seen in the P-C isotherms are confirmed from the powder X-ray dif fractogram of the alloy-hydrides with appropriate hydrogen concentration. T he powder X-ray diffractograms on the alloy-hydrides with maximum hydrogen concentration further show the absence of hydrogen induced amorphization (H 1A) upon hydrogenation. (C) 1999 Elsevier Science S.A. All rights reserved.