Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction

Richard A. Martin, Robert M. Moss, Robert J. Newport, Nilay J. Lakhkar, Jonathan C. Knowles, Gabriel J. Cuello, Mark E. Smith, John V. Hanna

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Abstract

Melt quenched silicate glasses containing calcium, phosphorus and alkali metals have the ability to promote bone regeneration and to fuse to living bone. Of these glasses 45S5 Bioglass® is the most widely used being sold in over 35 countries as a bone graft product for medical and dental applications; particulate 45S5 is also incorporated into toothpastes to help remineralize the surface of teeth. Recently it has been suggested that adding titanium dioxide can increase the bioactivity of these materials. This work investigates the structural consequences of incorporating 4 mol% TiO2 into Bioglass® using isotopic substitution (of the Ti) applied to neutron diffraction and X-ray Absorption Near Edge Structure (XANES). We present the first isotopic substitution data applied to melt quench derived Bioglass or its derivatives. Results show that titanium is on average surrounded by 5.2(1) nearest neighbor oxygen atoms. This implies an upper limit of 40% four-fold coordinated titanium and shows that the network connectivity is reduced from 2.11 to 1.97 for small quantities of titanium. Titanium XANES micro-fluorescence confirms the titanium environment is homogenous on the micron length scale within these glasses. Solid state magic angle spinning (MAS) NMR confirms the network connectivity model proposed. Furthermore, the results show the intermediate range order containing Na-O, Ca-O, O-P-O and O-Si-O correlations are unaffected by the addition of small quantities of TiO2 into these systems.

Original languageEnglish
Pages (from-to)15807-15815
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume14
Issue number45
Early online date8 Oct 2012
DOIs
Publication statusPublished - 5 Dec 2012

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    Martin, R. A., Moss, R. M., Newport, R. J., Lakhkar, N. J., Knowles, J. C., Cuello, G. J., Smith, M. E., & Hanna, J. V. (2012). Structural characterization of titanium-doped Bioglass using isotopic substitution neutron diffraction. Physical Chemistry Chemical Physics, 14(45), 15807-15815. https://doi.org/10.1039/c2cp43032k