Author: Muhammad Ayob
Ayob, Muhammad, 2019 Development of Silver-doped Phosphate Glasses for Radio Photoluminescence Glass Dosimeter, Flinders University, College of Science and Engineering
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A series of the radio-photoluminescent glass dosimeters (RPLGDs) with different ratios of chemical composition in the glass were successfully prepared using the wet melting method. RPLGDs are applicable for measurement of ionizing radiation at variant doses using silver-doped phosphate glass. When the RPLGD is exposed to γ-rays, electrons and holes produced by the γ-radiation are trapped by the Ag+ ions, producing Ag° and Ag2+ ions respectively, resulting in the emission of two RPL peaks at 460 and 620 nm. There were three main parts to this study which includes; 1) the silver nanoparticles (AgNPs) preparation, 2) formation of glasses with different ratios of chemical elements and 3) development of the RPLGD using the optimum ratio of chemical element composition with AgNPs. In this work, AgNPs with different sizes were prepared by polyol method. The basic physical and optical properties of the glasses, such as hardness, density, transmission, absorbance and photoluminescence values were analysed. The addition of protic polyethyleneimine and aprotic poly(sodium 4-styrene sulfonate) polymers produces different colour of final AgNPs solutions with yellow of AgNPs-PSS and colourless of AgNPs-Pei, respectively. Next, the glasses were prepared using wet chemical method and the optimal base composition range of phosphate glasses for RPLGDs was also investigated. The correlation between the RPLGD properties investigated and the glass compositions showed that the characteristic properties were dependant on the ratio of chemical compostition used. Based on thermo-physical and structural studies, the hardness test shows that the HRA values increased with increasing Al and Na content. Moreover, RPLGD series have the highest sensitivity between 3.0 to 5.0 wt.% of silver. Apart from that, the effect of various silver sizes addition on the phosphate glass microstructure, composition and chemical characteristics was investigated using X-ray diffraction, Fourier transform infrared and photoluminescence spectroscopy. It was established that the phosphate glasses suitable for dosimeter control possess density values ranging from 2.15 to 2.78 g.cm-3. FT-IR spectra of Ag-doped phosphate glasses have been studied before and after 100 Gy of γ-irradiation. The decrease in oxygen content of glass sample after γ-irradiation was indicated by bond breaking in the glass sample. The orange RPL at 620 nm was associated with the 325 nm of the excitation band and this optical activity was due to the Ag2+ centers. The photoluminescence study of AgNPs-doped phosphate glass showed enhanced radiation sensitivity towards γ-radiation compared with phosphate glass doped with bulk silver under the same conditions. The AgNPs with 4.3 wt% showed the highest γ-ray detection sensitivity, which showed the highest PL peaks at the same absorbed dose, followed by 2.5 wt% and 7.7 wt%. In conclusion, using AgNPs as activators in the RPLGD will enhance the radiation sensitivity due to the rapid and excellent growth of the RPL centers within the forbidden band of the glass formed by the initial ionizing event.
Keywords: Silver nanoparticles, Silver-doped Phosphate Glasses, Radio Photoluminescence Glass Dosimeter,
Subject: Chemistry thesis
Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Science and Engineering
Supervisor: Prof. David A. Lewis