Novel optical battery from glass-based materials
García Arango, Nicolás (2021)
2021
Master's Programme in Materials Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2021-04-26
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202104233403
https://urn.fi/URN:NBN:fi:tuni-202104233403
Tiivistelmä
The main goal of the thesis has been the preparation of a new optical battery made from glasses displaying green persistent luminescence (PeL) after being charged with infrared radiation. The base composition of the glasses was chosen from previous studies done by the Photonics Glasses Group in Tampere University. The novelty of this study was the use Ytterbium and Thulium, capable of absorbing infrared radiation and releasing visible light. Glasses were prepared using different techniques.
In the first technique, the glasses were prepared using standard melting process. The work was divided into 3 steps; the first one dealt with the study and optimization of blue upconversion (UC) in glasses after irradiation at 975 nm. Glasses with different Yb3+/Tm3+ ratios were prepared using standard melting process. The second stage was meant to develop glass-ceramics from the most promising glasses to increase the intensity of the blue UC. Different heat-treatments were applied and the blue upconversion upon infrared excitation measured. Results lead to interesting conclusions. Indeed, although the blue upconversion was greatly enhanced in the lowest Yb concentrated glass, the blue emission intensity decreased after heat-treating the glasses prepared with >2 mol % of Yb2O3, most likely due to short distances between the Yb3+ ions, as was also reported in a similar research. The third step consisted on adding various wt % of commercial green persistence luminescent particles to the most promising samples. Lasting green emission was observed after infrared charging, confirming the energy transfer from Yb3+ to the upconverting Tm3+ ions and then to the persistent luminescent particles demonstrating that an optical battery could be obtained from the newly developed glasses.
For the second technique, the blue upconversion from the glasses was obtained by adding NaYF4:Tm3+,Yb3+ nanocrystals and the PeL particles in the glass melt using the direct doping method. Some blue upconversion was observed but its intensity was probably too low to charge the PeL particles.
In the first technique, the glasses were prepared using standard melting process. The work was divided into 3 steps; the first one dealt with the study and optimization of blue upconversion (UC) in glasses after irradiation at 975 nm. Glasses with different Yb3+/Tm3+ ratios were prepared using standard melting process. The second stage was meant to develop glass-ceramics from the most promising glasses to increase the intensity of the blue UC. Different heat-treatments were applied and the blue upconversion upon infrared excitation measured. Results lead to interesting conclusions. Indeed, although the blue upconversion was greatly enhanced in the lowest Yb concentrated glass, the blue emission intensity decreased after heat-treating the glasses prepared with >2 mol % of Yb2O3, most likely due to short distances between the Yb3+ ions, as was also reported in a similar research. The third step consisted on adding various wt % of commercial green persistence luminescent particles to the most promising samples. Lasting green emission was observed after infrared charging, confirming the energy transfer from Yb3+ to the upconverting Tm3+ ions and then to the persistent luminescent particles demonstrating that an optical battery could be obtained from the newly developed glasses.
For the second technique, the blue upconversion from the glasses was obtained by adding NaYF4:Tm3+,Yb3+ nanocrystals and the PeL particles in the glass melt using the direct doping method. Some blue upconversion was observed but its intensity was probably too low to charge the PeL particles.