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Solid State Impedance Spectroscopy Study Bioglass 45S5 Doped with Fe

Bioactive glasses based on the system SiO2– P2O5– CaO–Na2O are reported to be able to stimulate more host bone regeneration than any other bioactive material. The incorporation of Fe ion in bioactive glass enhances the efficiency to promote cell attachment and proliferation. In this study, structural and electrical properties of 45S5 Bioglass doped with various amounts of Fe are investigated by DTA, Raman, and Impedance spectroscopies. The prepared based glass composition is 45% SiO2, 24.5% Na2O, 24.5% CaO and 6% P2O5 (wt%). Doped bioglasses are prepared with up to 6 %wt of Fe. For the electrical measurements, samples are prepared in form of ~1 mm thick disks. Gold electrodes, 3.8 mm in diameter, are sputtered onto both sides of disks using Sputter Coater. Electrical properties are studied by measuring complex impedance using an impedance analyzer. The Raman spectra of prepared bioglasses are similar in the range where bands characteristic for silica network (SiO44- and Si2O64- units) are dominant. However, detailed analysis revealed that with the increase of the amount of Fe additional bands associated with Fe bonds are present. The addition of 1% Fe shifts Tg and Tc to a higher value, while with further increase of Fe (up to 6%), the decreasing trend is observed. Each conductivity isotherm exhibits two features ; a plateau at lower frequencies that corresponds to the DC conductivity and frequency- dependent conductivity at higher frequencies. In addition to the two observed spectral features, spectra at highest temperatures, above 180 °C, exhibit a decrease of conductivity with decreasing frequency in the low-frequency region. The mechanism of electrical conduction is assigned to be ionic due to the modifier Na+ cation diffusion through the bulk. Since the conductivity depends on the number density of charge carriers and their mobility, with the increase of the amount of Fe, the total number of Na+ ions decreases, consequently resulting in a decrease of conductivity. All glasses obey both Summerfield and Sidebottom scaling procedures of conductivity spectra indicating that the conductivity mechanism does not change with the temperature.

Bioglass ; DTA ; Fe doping ; Impedance spectroscopy ; Raman spectroscopy

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