Abul Arafat, Sabrin A. Samad, Jeremy J. Titman, Andrew L. Lewis, Emma R. Barney, Ifty Ahmed
November 18, 2020
This study investigates the role of yttrium in phosphate-based glasses in the system 45(P 2 O 5 )–25(CaO)– (30-x)(Na 2 O)–x(Y 2 O 3 ) (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31 P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y 2 O 3 content as metaphosphate units (Q 2 ) decreased with subsequent increase in pyrophosphate species (Q 1 ). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca 2 P 2 O 7 ) and sodium metaphosphate (NaPO 3 ) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y 2 O 3 . Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y 2 O 3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yttrium (YO 6 ) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles.