کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1447894 | 988658 | 2010 | 11 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Hydrogenography of MgyNi1−yHx gradient thin films: Interplay between the thermodynamics and kinetics of hydrogenation Hydrogenography of MgyNi1−yHx gradient thin films: Interplay between the thermodynamics and kinetics of hydrogenation](/preview/png/1447894.png)
We monitor the hydrogenation of PTFE/Pd-capped MgyNi1−yHx gradient thin films using the change in optical transmission as a function of time, temperature and hydrogen pressure, to study the relation between kinetics and thermodynamics of hydrogenation of this multiphase hydride system. The interplay between kinetics and thermodynamics is used to extrapolate the hydrogenation equilibrium pressures via the H-absorption rate. Pressure–optical-transmission–isotherms determined independently at different temperatures provide a cross-check for the equilibrium pressure and the enthalpy of H-absorption. We find that the hydrogenation reaction is destabilized with respect to the Mg2Ni → Mg2NiH4 reaction for Mg fractions close to the Mg2Ni–Mg eutectic point. From a comparison with calculated enthalpies obtained from density functional theory, we conclude that the experimentally observed destabilization originates from the well-mixed microstructure around the eutectic point.
Journal: Acta Materialia - Volume 58, Issue 2, January 2010, Pages 658–668