The role of strontium and potassium on crystallization and bioactivity of Na2O–CaO–P2O5–SiO2 glasses

• Published in: Ceramics international Vol. 38; no. 1; pp. 55 - 63
• Main Authors: Salman, S M, Salama, S N, Abo-Mosallam, H A
• Format: Journal Article
• Language: English
• Published: 01-01-2012
• Subjects: Biochemistry; Calcium silicates; Crystallization; Glass; Glass ceramics; Sodium; Strontium; Wollastonite
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2011.06.037

The effect of SrO/CaO and K2O/Na2O replacements on the crystallisation process of glasses based on the Na2O-CaO-P2O5-SiO2 system was investigated. The glasses were thermally treated through controlled heat treatment regimes to obtain glass-ceramics. Combeite Na2Ca2Si3O9, sodium calcium silicate Na2Ca3Si6O16, wollastonite solid solution, and whitlockite Ca3(PO4)2 were identified as the major crystalline phases in the thermally treated glasses. No potassium- and strontium-containing phases were detected in the glass-ceramics; potassium seemed to be accommodated in the wollastonite structure, while strontium was incorporated into the sodium calcium silicate structure. The surface reactivity of the prepared glass-ceramic specimens was also studied in vitro in Kokobo's simulated body fluid (SBF). EDAX, SEM, ICP, and FTIR were used to examine the formation of apatite surface layers and characterise the glass-ceramic surface and SBF compositional changes. A decrease in the bioactivity of the glass-ceramic was observed as Na2O was replaced by K2O. Strontium together with calcium ions in the apatite layer formed was detected for SrO/CaO replacement. The role played by the glass oxide constituents in determining the crystallisation and bioactivity behaviour of the prepared thermally treated glasses is discussed.