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Snow, Clark Sheldon

Publications and source records attributed to Snow, Clark Sheldon.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

In Situ Electron Microscopy of Helium Bubble Implantation in Metal Hydrides

Here we investigated the microstructural response of various Pd physically vapor deposited films and Er and ErD 2 samples prepared from neutron Tube targets to implanted He via in situ ion irradiation transmission electron microscopy and subsequent in situ annealing experiments. Small bubbles formed in both systems during implantation, but did not grow with increasing fluence or a short duration room temperature aging (weeks). Annealing produced large cavities with different densities in the two systems. The ErD 2 showed increased cavity nucleation compared to Er. The spherical bubbles formed from high fluence implantation and rapid annealing in both Er and ErD 2 cases differed from microstructures of naturally aged tritiated samples. Further work is still underway to determine the transition in bubble shape in the Er samples, as well as the mechanism for evolution in Pd films.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Characterization of the surface changes during the activation process of erbium/erbium oxide for hydrogen storage.

Erbium is known to effectively load with hydrogen when held at high temperature in a hydrogen atmosphere. To make the storage of hydrogen kinetically feasible, a thermal activation step is required. Activation is a routine practice, but very little is known about the physical, chemical, and/or electronic processes that occur during Activation. This work presents in situ characterization of erbium Activation using variable energy photoelectron spectroscopy at various stages of the Activation process. Modification of the passive surface oxide plays a significant role in Activation. The chemical and electronic changes observed from core-level and valence band spectra will be discussed along with corroborating ion scattering spectroscopy measurements.

08 HYDROGEN↗
DOE OSTI2010

In-situ observation of ErD2 formation during D2 loading via neutron diffraction.

In an effort to better understand the structural changes occurring during hydrogen loading of erbium target materials, we have performed in situ D{sub 2} loading of erbium metal (powder) at temperature (450 C) with simultaneous neutron diffraction analysis. This experiment tracked the conversion of Er metal to the {alpha} erbium deuteride (solid-solution) phase and then into the {beta} (fluorite) phase. Complete conversion to ErD{sub 2.0} was accomplished at 10 Torr D{sub 2} pressure with deuterium fully occupying the tetrahedral sites in the fluorite lattice.

08 HYDROGEN↗