Effects of magnesium content on the physical, chemical and degradation properties in a MgO−CaO−Na2O−P2O5 glass system

• Published in: Journal of non-crystalline solids Vol. 363; pp. 57 - 63
• Main Authors: Lee, In-Ho, Shin, Song-Hee, Foroutan, Farzad, Lakhkar, Nilay J., Gong, Myoung-Seon, Knowles, Jonathan C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.03.2013; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Degradation; Disordered solids; Exact sciences and technology; Glass; Glasses; Glasses (including metallic glasses); Magnesium; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Materials science; Nuclear magnetic resonance and relaxation; Phosphate; Physics; Specific materials; Structure of solids and liquids; crystallography; Degradation; Magnesium; Phosphate; Glass; Phosphates; Fourier transform spectroscopy; Calcium oxide; Magnesium oxide; Differential thermal analysis; Glass structure; Ionic radius; Bond lengths; Chemical properties; Nuclear magnetic resonance; Fourier-transformed infrared spectrometry
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2012.11.036

This paper presents the structural characterisation and degradation behavior of the glass system 20Na2O–(30−X)CaO–XMgO–50P2O5 (X=0, 5, 10, 15, 20, 25 and 30mol%) wherein magnesium oxide is introduced as a partial calcium oxide substitute. This system is of interest from the viewpoint of investigating the subtle effects on structure and degradation that arise from the substitution of divalent ions (Mg2+ for Ca2+) in these glass systems. Studies such as differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy and 31P nuclear magnetic resonance (NMR) reveal little change in the glass structure. However, degradation and ion release measurements for glass discs immersed in deionised water at 37°C over a 21day period highlight an inverse exponential effect between glass degradation rate and MgO content. Thus, the investigated glass systems provide interesting insights into the effects of parameters such as ionic radius, atomic weight and bond length on the glass properties. From an applications perspective, these glasses offer a selective range of degradation rates from highly degradable to relatively stable systems and can potentially serve as vehicles for the delivery of magnesium ions in the clinical realm. ► Substitution of CaO with MgO allows control of the degradation and pH changes. ► The change in degradation and pH is more strongly influenced by ionic size than by ionic charge. ► No change in surface energy properties may be seen.