Vitrification of β-tricalcium phosphate in sodium aluminoborophosphate glass and the effect of Ga3+ substitution

Abstract Sodium calcium aluminoborophosphate glasses (some containing Ga 3+ ) simulate interactions at the interface between β-tricalcium phosphate crystal waste hosts (β-TCP and β-TC(Ga)P) and sodium aluminoborophosphate (NABP) glass encapsulant. 31 P NMR and Raman spectroscopies show progression from Na + charge-balanced, mixed Q Al P = Q 2 1 + Q 3 0 in the NABP base glass, to Ca 2+ charge-balanced, Q 0 0 dominated structure, eventually inhibiting vitrification above 80 wt% addition of β-TCP or β-TC(Ga)P. 27 Al NMR shows [Al(PO 4 ) n ] species with dominant n =4 and 11 B NMR shows the 4-coordinated boron fraction in NABP falls from 0.7 to 0.1 on addition of the crystal hosts. Devitrification of glasses with 60–70 wt% crystal additions shows that Na + and Al 3+ from the encapsulant substitute for ∼20% of Ca 2+ in the β-TCP phase formed from the β-TCP:NABP glasses whilst ∼85% of Ga 3+ resubstitutes into β-TCP from the β-TC(Ga)P:NABP glasses. This demonstrates the preference for Ga 3+ substitution over Al 3+ in the Ca(5) site.