A class of melt‐quenched silicate glasses, containing calcium, phosphorus and alkali metals, and having the ability to promote bone regeneration and to fuse to living bone, creating strong implants with less danger of interfacial instability than previous materials, is produced commercially as Bioglass® and sold under the brand names of PerioGlas®, NovaBone® and NovaBone‐C/M®. We have collected the first high energy X‐ray and neutron diffraction data, on this important material in the hope of providing more direct experimental insight into the glass structure. Similarly, the first solid state MAS (magic angle spinning) 29Si, 31P, and 23Na NMR data on the material is presented. The diffraction data has been modeled using the reverse Monte Carlo (RMC) method to allow the identification of the atomic‐scale structural features present; the solid state NMR data is used explicitly within the model‐building process as a constraint on the connectivity of the network. The 29Si NMR suggests that the host silica network primarily consists of chains and rings of Q2 SiO4 tetrahedra, with some degree of cross linking as represented by the presence of Q3 units. The diffraction‐based RMC model suggests a Na–O distance of 2.35 Å and a corresponding coordination of ∼ 6; the coordination number is supported by the 23Na NMR data presented here which reveals that the likely sodium environment is six‐coordinate in pseudo‐octahedral arrangement. The RMC model provides evidence for the non‐uniform distribution of Ca, which is in line with previous molecular dynamics simulation results, and the data is also suggestive of CaO as the associated structural motif within the high calcium content regions of the glass.

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Strontium has been substituted for calcium in the glass series (SiO 2) 49.46 (Na 2 O) 26.38 (P 2 O 5) 1.07 (CaO) 23.08Àx (SrO) x (where x ¼ 0, 11.54, 23.08) to elucidate their underlying atomic-scale structural characteristics as a basis for understanding features related to the bioactivity. These bioactive glasses have been investigated using isomorphic neutron and X-ray diffraction, Sr K-edge EXAFS and solid state 17 O, 23 Na, 29 Si, 31 P and 43 Ca magic-angle-spinning (MAS) NMR. An effective isomorphic substitution first-order difference function has been applied to the neutron diffraction data, confirming that Ca and Sr behave in a similar manner within the glass network, with residual differences attributed to solely the variation in ionic radius between the two species. The diffraction data provides the first direct experimental evidence of split Ca-O nearest-neighbour correlations in these meltquench bioactive glasses, together with an analogous splitting of the Sr-O correlations; the correlations are attributed to the metal ions correlated either to bridging or to non-bridging oxygen atoms. Triple quantum (3Q) 43 Ca MAS NMR corroborates the split Ca-O correlations. Successful simplification of the 2 < r (A) < 3 region via the difference method has also revealed two distinct Na environments. These environments are attributed to sodium correlated either to bridging or to nonbridging oxygen atoms. Complementary multinuclear MAS NMR, Sr K-edge EXAFS and X-ray diffraction data supports the structural model presented. The structural sites present will be intimately related to their release properties in physiological fluids such as plasma and saliva, and hence the bioactivity of the material. Detailed structural knowledge is therefore a prerequisite for optimising material design.

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A sol-gel preparation of Ga-doped phosphate-based glass with potential application in antimicrobial devices has been developed. Samples of composition (CaO) 0.30 (Na 2 O) 0.20-x (Ga 2 O 3 ) x (P 2 O 5 ) 0.50 where x = 0 and 0.03 were prepared, and the structure and properties of the gallium-doped sample compared with those of the sample containing no gallium. Analysis of the 31 P MAS NMR data demonstrated that addition of gallium to the sol-gel reaction increases the connectivity of the phosphate network at the expense of hydroxyl groups. This premise is supported by the results of the elemental analysis which showed that the gallium-free sample contains significantly more hydrogen and by FTIR spectroscopy, which revealed a higher concentration of OH groups in that sample. Ga K-edge EXAFS and XANES data revealed that the gallium ions are coordinated by six oxygen atoms. In agreement with the X-ray absorption data, the high-energy XRD results also suggest that the Ga 3+ ions are octahedrally coordinated with respect to oxygen. Antimicrobial studies demonstrated that the sample containing Ga 3+ ions had significant activity againstStaphylococcus aureus compared to the control.