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Acoustic and structural properties of x CaO · (1–x ) B2O3 (0.2 ≤ x ≥ 0.7) glass system have been studied at ambient temperature. The ultrasonic velocity and attenuation for different compositions of calcium borate glasses were measured at 5 MHz at room temperature (303 K) using a pulse echo overlap method. The elastic moduli, Debye temperature, Poisson's ratio and other acoustic parameters have been obtained from experimental data. Fourier transform infrared spectroscopic analysis has been used to further support the results of acoustic studies. The results obtained indicate that the calcium oxide enters the glass network as a modifier by occupying the interstitial spaces in the network and by increasing the nonbridging oxygen atoms (NBOs). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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In vitro bioactivity of borate glasses with composition xNa2O·xCaO·2xB2O3 (where x is in wt%=24.8, 24.2, 23.8, 23.2) containing 0, 2, 4, 6 wt% P2O5 has been investigated by soaking them in a simulating body fluid (SBF) up to 15 days at 37°C. Investigation of glass degradation is carried out by taking percentage weight loss in SBF and by measuring the pH of SBF as a function of time. Inductively coupled plasma emission spectroscopy is used to study the ionic concentration of BIII, CaII, and NaI ions in SBF after 15 days of assay. Fourier transform infrared spectra are taken before and after dipping in SBF for structural analysis and for confirmation of hydroxyl carbonate apatite layer formation in SBF after 15 days. The results show that P2O5 plays an important role in controlling chemical durability and bioactivity. A borate glass with the same composition as 45S5 bioglass prepared by Hench but with SiO2 replaced by B2O3 in weight percentage has been prepared for comparison of bioactivity for the two.