Process-Structure-Property Relationships of Micron Thick Gadolinium Oxide Films Deposited by Reactive Electron Beam-Physical Vapor Deposition (EB-PVD)
PENNSYLVANIA STATE UNIV STATE COLLEGE APPLIED RESEARCH LAB
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Gadolinium oxide GdoG is an attractive material for solid state neutron detection due to gadoliniums high thermal neutron capture cross section. Development of neutron detectors based on GdaCh requires sufficiently thick films to ensure neutron absorption. In this dissertation work, the process-structure-property relationships of micron thick GdCb films deposited by reactive electron-beam physical vapor deposition EB-PVD were studied. Through a systematic design of experiments, fundamental studies were conducted to determine the effects of processing conditions such as deposition temperature, oxygen flow rate, deposition rate, and substrate material on Gd2G3 film crystallographic phase, texture, morphology, grain size, density, and surface roughness. Films deposited at high rates 5 s were examined via x-ray diffraction XRD and Raman spectroscopy. Quantitative phase volume calculations were performed via a Rietveld refinement technique. All films deposited at high rates were found to be fully monoclinic or mixed cubic monoclinic phase. Generally, increased deposition temperature and increased oxygen flow resulted in increased cubic phase volume. As film thickness increased, monoclinic phase volume generally increased. Grazing incidence x-ray diffraction GIXRD depth profiling analysis showed that cubic phase was only present under large incidence angle large penetration depth into the film measurements, and that after a certain point, only monoclinic phase was grown. This was confirmed by transmission electron microscopy TEM analysis in conjunction with selected area diffraction SAD.
- Inorganic Chemistry