Date of Award

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Materials Science and Engineering

Committee Member

Luiz G. Jacobsohn, Committee Chair

Committee Member

Kyle S. Brinkman

Committee Member

Timothy A. DeVol

Committee Member

Fei Peng

Abstract

Polycrystalline ceramic scintillators have received increasing attention due to a number of advantages over single crystals, including faster production and lower fabrication costs and easier fabrication of materials with high melting temperatures. Nevertheless, scintillation performance of polycrystalline ceramics is commonly inferior to single crystals. In the present work, a detailed comparative investigation of the family of garnet scintillators in the form of polycrystalline ceramic and single crystal scintillators was performed in terms of their microstructure, as well as optical and luminescent properties, to gain insight into the factors influencing their scintillation performance. The use of infrared vibrational spectroscopy to gain relevant microstructural information was demonstrated for polycrystalline ceramic scintillators. The investigation was focused on Y3Al5O12:Ce (YAG:Ce), Lu3Al5O12:Ce (LuAG:Ce), Lu3Al5O12:Pr (LuAG:Pr), mixed garnets (Lu,Gd)3(Al,Ga)5O12:Ce, and Li7La3Zr2O12:Ce (LLZO:Ce). Evaluation and analysis of material properties revealed reasons for lower performance of polycrystalline ceramic scintillators including lower optical transparency, higher level of structural disorder, higher self-absorption, and possibly shallower traps. This work reports for the first time a systematic evaluation of microstructure, luminescence, and scintillation performance of (Lu,Gd)3(Al,Ga)5O12:Ce in the form of polycrystalline ceramics focusing on the effect of the substitution of Lu3+ with Gd3+, and also the fabrication and characterization of luminescent properties of Ce-doped Li7La3Zr2O12 towards the discovery of new scintillating materials.

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