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Title page for ETD etd-08052010-142925

Type of Document Dissertation
Author Hansel, Rachael Ann
Author's Email Address rachaelann.hansel@gmail.com
URN etd-08052010-142925
Title Phosphor thermometry using rare-earth doped materials
Degree PhD
Department Interdisciplinary Materials Science
Advisory Committee
Advisor Name Title
D. Greg Walker, Ph.D. Committee Chair
Charles Lukhart, Ph.D. Committee Member
Richard Haglund, Ph.D. Committee Member
Stephen W. Allison, Ph.D. Committee Member
Timothy Hanusa, Ph.D. Committee Member
  • thermometry
  • pyrochlores
  • garnets
  • luminescent lifetime
  • temperature
  • phosphors
Date of Defense 2010-07-29
Availability unrestricted
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.

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