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Date of Award

10-6-2015

Document Type

Thesis and Dissertation-ISU Access Only

Degree Name

Master of Science (MS)

Department

Department of Chemistry

First Advisor

Eirin C. Sullivan

Abstract

Light emitting diodes (LEDs) are an attractive alternative to traditional incandescent and fluorescent lights as they offer superior efficiency and lifetime. Phosphor conversion LEDs (PC-LEDs) combine either a blue LED and a yellow phosphor, or a UV LED with a mixture of red, green, and blue phosphors. The development of more efficient and higher color quality phosphors is an important avenue of solid state research.

One material that has shown promise as a phosphor is the tetragonal anti-perovskite Sr3MO4F (M= Al, Ga). Sr3MO4F has been found to display significant photoluminescence when doped with trivalent lanthanides such as cerium, samarium, europium, terbium, erbium, and thulium on the strontium site. Unfortunately, these rare earth doped phosphors are very expensive and must be imported; therefore, phosphors made of more readily available materials would be preferable. Studies have shown that divalent manganese induces photoluminescence in anti-perovskites and germanates; while, trivalent bismuth induces photoluminescence in garnets. Sr3MO4F materials have also been found to be photoluminescent when reduced under dilute hydrogen gas.

The research presented in this thesis explores how doping Sr3MO4F with manganese and bismuth influence the structure and photoluminescent properties of the host lattice. It further explores how these doped lattices are affected by exposure to reducing conditions. To this end, phases of the general formulae Sr3-xMnxAlO4F, Sr3-xMnxGaO4F, Sr3-xBi2x/3AlO4F, Sr3-xBi2x/3GaO4F, and Sr3-xMnxAlO4-αF1-δ were synthesized by the ceramic method. To determine the structure of these materials powder X-ray diffraction, high resolution neutron powder diffraction, Rietveld refinement, and thermogravimetric analysis were employed. Spectrofluorimetry was used to characterize the photoluminescent properties of the materials.

Comments

Imported from ProQuest Quilty_ilstu_0092N_10636.pdf

Page Count

134

Available for download on Sunday, January 14, 2018

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