resumo
The study of SiO2-MgO-Na2O glasses is of particular relevance because some compositions can exhibit adequate properties for their use in biomedical applications. The influence of substitution of divalent Mg2+ ions for monovalent Na+ in the structure of silicate glasses which contain 55 mol% SiO2 was investigated by Magic-Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR), Raman spectroscopy and Fourier Transformed Infrared Spectroscopy (FTIR), in both qualitative and quantitative basis. According to the results, the structure of the glasses predominantly comprised Q(2) and Q(3) structural species. In glasses with more than 25% molar MgO, the substitution of Na2O by MgO promotes a significant change in the main silicate chain through a disproportionation reaction 2Q(2) reversible arrow Q(1) + Q(3), while glasses with less than 20% molar MgO show no evidence of silicate chain modifications. Information about the glass structure is of major importance for the understanding of the parameters that can control the biomedical properties, such as the chemical dissolution rate, pH and cell viability. (C) 2010 Elsevier B.V. All rights reserved.
palavras-chave
ALKALI-SILICATE-GLASSES; ALUMINOSILICATE GLASSES; BIOACTIVE GLASSES; VITREOUS SILICA; SPECTROSCOPY; MELTS; TEMPERATURE; PRESSURE; SPECTRA; SIO2
categoria
Chemistry
autores
Silva, AMB; Queiroz, CM; Agathopoulos, S; Correia, RN; Fernandes, MHV; Oliveira, JM
nossos autores
J. Martinho Oliveira
Professor Coordenador
Maria Helena Figueira Vaz Fernandes
Professor(a) Jubilado(a)Grupos
G4 - Materiais Renováveis e Economia Circular
G5 - Materiais Biomiméticos, Biológicos e Vivos
agradecimentos
The first author acknowledges the Portuguese Foundation of Science and Technology for the financial support through the Project POCTI/CTM/60761/2004.; The second and the third authors acknowledge the financial support of the Portuguese Foundation of Science and Technology under the PRAXIS-XXI grants SFRH/BPD/1619/2000 and SFRH/BD/1243/2000, respectively.