Surface and bulk phenomena in the process of hydride formation in thin films of rare earth metals: Comparison between terbium and europium

► Two rare earth metals, europium and terbium, have been compared in hydride formation. ► Hydrogen interaction with Eu or Tb films at 298 K leads to metal-semiconductor transition. ► Different resistance courses of Eu and Tb hydride films versus hydrogen content are noticeable. ► The inversion of polarization of the hydrogen adspecies is noted for both metals. ► Low temperature ordered surface phase of hydride for Tb (<100 K) and Eu (<160 K) is suggested.