Photo-response of phosphate glasses during radiation treatment
Lahti, Vilma (2023)
Lahti, Vilma
2023
Teknis-luonnontieteellinen DI-ohjelma - Master's Programme in Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2023-12-14
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2023113010376
https://urn.fi/URN:NBN:fi:tuni-2023113010376
Tiivistelmä
The goal of this project was to study the effects of laser irradiation on the structural and spectroscopic properties of Er3+ doped phosphate glasses with and without silver.
Glasses with the composition (100 – 0.25 – x) (75 NaPO3 – 25 CaF2) – 0.25 Er2O3 – x Ag2O (in mol-%), where x = 0 or x = 4 were prepared using melting process. After the glasses were annealed, they were polished, and heat treated with the goal to precipitate Er3+ doped CaF2 crystals as well as silver nanoparticles in the glasses. The as-prepared and heat-treated glasses were irradiated after determining the ablation threshold of the glasses and finding out what parameters would be most suited for the irradiation. The surface profiles of the irradiated samples were measured using a profilometer to evidence ablation or expansion/contraction of the glass surface during the radiation treatment. The structural and spectroscopic properties of the irradiated glasses were measured prior and after irradiation.
The glasses irradiated with CO2 laser showed that the crystallization and addition of Ag2O decrease the photosensitivity of the glasses. The formation of the silver nanoparticles causes the glass to become more photosensitive. Signs of contraction of the network is expected to occur when using a fs laser at low pulse energies. The contraction is thought to be due to defect formation as suspected from the changes in the structural and spectroscopic properties of the glasses after irradiation. The glasses do not crystallize nor amorphize as a result of the irradiation. However, silver nanoparticles are suspected to form when using high-power laser irradiation, but only when the glass is heat treated before irradiation.
In this project, we were able to show that the growth of silver nanoparticles is possible with a CO2 laser, but the preparation of the samples needs to be optimized to achieve more consistent results.
Glasses with the composition (100 – 0.25 – x) (75 NaPO3 – 25 CaF2) – 0.25 Er2O3 – x Ag2O (in mol-%), where x = 0 or x = 4 were prepared using melting process. After the glasses were annealed, they were polished, and heat treated with the goal to precipitate Er3+ doped CaF2 crystals as well as silver nanoparticles in the glasses. The as-prepared and heat-treated glasses were irradiated after determining the ablation threshold of the glasses and finding out what parameters would be most suited for the irradiation. The surface profiles of the irradiated samples were measured using a profilometer to evidence ablation or expansion/contraction of the glass surface during the radiation treatment. The structural and spectroscopic properties of the irradiated glasses were measured prior and after irradiation.
The glasses irradiated with CO2 laser showed that the crystallization and addition of Ag2O decrease the photosensitivity of the glasses. The formation of the silver nanoparticles causes the glass to become more photosensitive. Signs of contraction of the network is expected to occur when using a fs laser at low pulse energies. The contraction is thought to be due to defect formation as suspected from the changes in the structural and spectroscopic properties of the glasses after irradiation. The glasses do not crystallize nor amorphize as a result of the irradiation. However, silver nanoparticles are suspected to form when using high-power laser irradiation, but only when the glass is heat treated before irradiation.
In this project, we were able to show that the growth of silver nanoparticles is possible with a CO2 laser, but the preparation of the samples needs to be optimized to achieve more consistent results.