The electromigration of H in YHx was studied by using a simple optical technique. It was found that the YH3-δ/YH2+ε phase boundary moved towards the anode with a velocity that became constant after long times. A spectacular effect occurred when the phase boundary reached an artificial discontinuity in the electric field: a so-called H traffic jam formed. This phenomenon was successfully simulated by using exact solutions to a non-linear electromigration equation, and a wind force coefficient of -23mΩcm. In principle, it was possible to attain chemical potentials (in the traffic-jam area) which were comparable to those in high-pressure experiments.

A Hydrogen Traffic Jam in YHx. S.J.Van der Molen, W.H.Huisman, R.Griessen: Journal of Alloys and Compounds, 2002, 330-332, 430-3