Insights into structural characterisation and thermal properties of compositionally equivalent vapour-condensed and melt-quenched glasses. (5th December 2016)

• Record Type: Journal Article
• Authors: Stuart, Bryan W.; Titman, Jeremy J.; Gimeno-Fabra, Miquel; Ahmed, Ifty; Grant, David M.
• Is Part Of: Materials & design. Volume 111(2016)
• Page Start: 174
• Page End: 184
• Publication Date: 2016-12-05
• Subjects: Bioactive glasses -- Magnetron sputtering -- Thermal characterisation -- Thin-film NMR -- PVD; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.08.063
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Physical vapour deposition of Phosphate-based glasses enables their application onto load bearing implant surfaces for their potential to enhance osseointegration by leaching therapeutic ions at the bone/implant interface. Structural understanding with respect to processing parameters will prove useful in the on-going production of multi-functional coatings for antibacterial ion release and osseous tissue integration. This study highlights significant differences in short-range structural variation between vapour condensed and conventional melt-quenched phosphate glasses, via 31 P MAS-NMR, XPS, FTIR and DTA. Three coating compositions containing P2 O5 - 32.5, 34 and 37 mol% showed greater bulk network polymerisation based on the presence of (23% to 45% Q 2 species) versus (9% to 32% Q 2 species) in melt-quenched glasses as determined by NMR. The proportion of P-O-P bridging oxygens as suggested by XPS on the surface of coatings remained consistent at (34% to 35%) forming (PO3 ) − metaphosphates (Q 2 ), whilst P‐O‐P bonding in melt-quenched glasses increased from (12% to 18%) and were found to form (PO4 ) 3 − orthophosphates (Q 0 ) and (P2 O7 ) 4 − pyrophosphates (Q 1 ). AFM analysis of the coating surfaces showed nano-topographical changes due to etch pitting, which led to Ra increases from 19 nm to 167 nm, which correlated to an increased deposition rate and therefore bombardment energy. Graphical abstract: Highlights: Novel production of phosphate based glasses by vapour deposition for future application onto medical implants. Phosphate glasses of equivalent composition vary in structure due to processing by PVD or conventional quenching. Greater polymerisation in coatings leads to their lower stability compared to melt quenched glasses during dissolution.