The goal of this work was to determine the luminescent lifetime of these phosphor
materials as a function of temperature. Cerium-doped yttrium aluminum garnet and
europium-doped pyrochlores were synthesized using combustion synthesis. The
phosphors were characterized using X-ray diffraction, transmission electron microscopy,
and photoluminescence spectroscopy. Lifetime measurements were taken over a range of
temperatures. The garnet materials exhibited thermal quenching between 30-125 ◦ C . In
contrast, the pyrochlore materials did not exhibit thermal quenching until well past 300 ◦ C
. The results presented in this work have shown that high energy states, such as the charge
transfer state or the d -orbitals, play a key role in the thermal quenching properties of
materials. For Ce-doped materials, our results indicate that materials which cause the
splitting of the d -orbitals to increase will cause the emission from the d1
→ 4 f transition
to thermally quench at higher temperatures. The lifetime of the 5 D0
→ 4 f emission line of
Eu3+ is dependent on the location of the charge transfer state. We suggest that the reason
higher quenching temperature are observed in materials such as YBO3 : Eu and the other
pyrochlores is because these materials have high-energy charge transfer states. Tuning
Eu3+ materials to maximize the energy of the charge transfer state may improve thermal
quenching properties of thermographic phosphors.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-08052010-142925 |
| Date | 17 August 2010 |
| Creators | Hansel, Rachael Ann |
| Contributors | Charles Lukhart, Ph.D., Richard Haglund, Ph.D., Timothy Hanusa, Ph.D., Stephen W. Allison, Ph.D., D. Greg Walker, Ph.D. |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-08052010-142925/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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