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The effect of MgO/TiO 2 on structural and crystallization behavior of near invert phosphate‐based glasses
Author(s) -
Islam Md Towhidul,
Sharmin Nusrat,
Rance Graham A.,
Titman Jeremy J.,
Parsons Andrew J.,
Hossain Kazi M. Zakir,
Ahmed Ifty
Publication year - 2020
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.34421
Subject(s) - crystallization , activation energy , glass transition , fourier transform infrared spectroscopy , raman spectroscopy , materials science , thermal stability , analytical chemistry (journal) , thermal analysis , nuclear chemistry , crystallography , chemistry , chemical engineering , thermal , thermodynamics , organic chemistry , physics , optics , engineering , composite material , polymer
Varying formulations in the glass system of 40P 2 O 5 ─(24 − x )MgO─(16 + x )CaO─(20 − y )Na 2 O─ y TiO 2 (where 0 ≤ x ≤ 22 and y = 0 or 1) were prepared via melt‐quenching. The structure of the glasses was confirmed by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), micro Raman and solid‐state nuclear magnetic resonance (NMR) spectroscopies. The thermal properties and the activation energy of crystallization ( E c ) were measured using thermal analysis and the Kissinger equation, respectively. The glass forming ability of the formulations investigated was seen to decrease with reducing MgO content down to 8 mol% and the glass stability region also decreased from 106 to 90°C with decreasing MgO content. The activation energy of crystallization ( E c ) values also decreased from 248 (for 24 mol% MgO glass) to 229 kJ/mol (for the 8 mol% MgO content) with the replacement of MgO by CaO for glasses with no TiO 2 . The formulations containing less than 8 mol% MgO without TiO 2 showed a strong tendency toward crystallization. However, the addition of 1 mol% TiO 2 in place of Na 2 O for these glasses with less than 8 mol% MgO content, inhibited their crystallization tendency. Glasses containing 8 mol% MgO with 1 mol% TiO 2 revealed a 12°C higher glass transition temperature, a 14°C increase in glass stability against crystallization and a 38 kJ/mol increase in E c in comparison to their non TiO 2 containing counterpart. NMR spectroscopy revealed that all of the formulations contained almost equal percentages of Q 1 and Q 2 species. However, FTIR and Raman spectroscopies showed that the local structure of the glasses had been altered with addition of 1 mol% TiO 2 , which acted as a network modifier, impeding crystallization by increasing the cross‐linking between phosphate chains and consequently leading to increased E c as well as their glass forming ability.