Engineering Commons^™

Development And Improvement Of Cerium Activated Gadolinium Gallium Aluminum Garnets Scintillators For Radiation Detectors By Codoping, Fang Meng

Doctoral Dissertations

Ce doped Gd3Ga3Al2O12 [gadolinium gallium aluminium oxides] is considered as a promising candidate for the next generation Positron Emission Tomography material due to its high light yield in theory. This dissertation is focused on studying the Gd3Ga3Al2O12:Ce crystals by codoping, aiming to improve the light yield and decay time experimentally and understand the underlying mechanism.

The work starts from prescreening appropriate codopants for Gd3Ga3Al2O12:Ce crystals. A cost-effective method is developed to predict the performance of the single crystals by characterizing the radioluminescence intensity and photoluminescence decay of the small polycrystalline pellets. This method is demonstrated by showing that the results …

The Experimental And Theoretical Study Of Plasticity Improvement Of Zr-Based Bulk Metallic Glasses, Xie Xie

Doctoral Dissertations

Bulk metallic glasses (BMGs) attract more and more attention for their great mechanical properties, such as high strength, good corrosion resistance, etc. However, even though extensive studies have been made, their deformation mechanisms are still not well understood. Their limited plasticity and catastrophic failure after yielding severely prevent their broad applications in industry and daily life. To improve their plasticity, some work has been done through miscellaneous processing methods, e.g., thin-film coating, surface treatment, and ion irradiation. The present work also focuses on the plastic deformation of BMGs, and is expected to deepen the fundamental understanding of the deformation mechanisms …

Engineering The “Pluripotency” Of Zr-Based Bulk Metallic Glasses As Biomedical Materials, Lu Huang

Doctoral Dissertations

Bulk metallic glasses (BMGs) are a family of novel alloys with amorphous microstructures. The combination of their excellent mechanical properties, good chemical stability, high thermal formability, and general biocompatibility has brought up new opportunities for biomaterials. Research in this dissertation was focused on exploring multiple biomedical functionalities of Zr-based BMGs over a wide spectrum, combining materials and biological characterizations, through experimental and computational approaches. Four distinct yet interconnected tasks were endeavored, involving inflammation, hard-tissue implant, soft-tissue prosthesis, and pathogenic infection.

The inflammation that can be potentially triggered by Zr-based BMGs was investigated using macrophages. Lower level or comparable macrophage activations …

Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek

Doctoral Dissertations

This multipart dissertation focuses on the development and evaluation of advanced methods for material testing and characterization using neutron diffraction and imaging techniques. A major focus is on exploiting diffraction contrast in energy selective neutron imaging (often referred to as Bragg edge imaging) for strain and phase mapping of crystalline materials. The dissertation also evaluates the use of neutron diffraction to study the effect of multi-axial loading, in particular the role of applying directly shear strains from the application of torsion. A portable tension-torsion-tomography loading system has been developed for in-situ measurements and integrated at major user facilities around the …