Electronic Theses and Dissertations

Identifier

4851

Date

2017

Document Type

Thesis

Degree Name

Master of Science

Major

Physics

Concentration

Materials Science

Committee Member

Dr. Firouzeh Sabri

Committee Member

Dr. Jingbiao Cui

Committee Member

Dr. Muhammad S. Jahan

Abstract

Abstract Phosphor thermometry has been investigated in recent years as means to explore instantaneous remote thermometry. Many different types of thermographic powders exist. In most cases work has been performed on these materials while in a fine powder form. There are significant challenges when working with fine powders (nm-µm particle size) and these challenges have limited the range of characterizations and potential applications of these materials. Among the different types of thermographic phosphors La2O2Su:Eu is one of the most sensitive types that is currently available. Lanthanum oxysulfide doped with Eu has been reported to have a sensitivity of 0.01 °C with a wide temperature range of response-cryogenics to 1500 °C. In this work two types of La2O2S:Eu (0.1 % and 1.0% Eu concentration) have been fully characterized at cryogenic temperatures and at elevated temperatures while embedded in an elastomeric sleeve. The flexible optically transparent elastomer Sylgard 184 was chosen as the encapsulant for this study. Samples with increasing levels of La2O2S:Eu powder (from 1 wt % to 25 wt%) were prepared and studied. Both single layer (single concentration) and multilayer (concentration gradient) sample types were prepared using spin-coating techniques and fully characterized. The effect of the La2O2Su:Eu particles on the thermal, mechanical, and luminescence behavior of the composite materials was fully investigated and reported here. While the percentage of the Eu (0.1 versus 1.0%) did not have a detectable effect on the emission characteristics of the composites, it did indeed affect the thermal and mechanical properties of the composites. SEM investigation suggests that the differences in the granular structure of the two powders has influenced the properties of the composite polymers prepared in this study. Furthermore, the emission behavior of the La2O2Su:Eu+Sylgard184 composites showed a strong non-linear temperature dependence in the range of -40 °C to 75 °C and little dependence on the powder concentration level.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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