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Home  >  Journal list  >  Journal of the Ceramic Society of Japan  >  Vol.123  No.1442 (October) (2015)  >  pp.942-948

Journal of the Ceramic Society of Japan
<<Previous article Vol.123  No.1442 (October) (2015)   pp.942 - 948 Next article>>

Structure and dissolution behavior of MgO–P2O5–TiO2/Nb2O5 (Mg/P ≥ 1) invert glasses

Sungho LEE1), Hirotaka MAEDA1), Akiko OBATA1), Kyosuke UEDA2), Takayuki NARUSHIMA2), Toshihiro KASUGA1)
1) Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology 2) Department of Metallurgy, Materials Science and Materials Processing, Graduate School of Engineering, Tohoku University

Magnesium phosphate glasses exhibit unusual properties and were classified as ‘anomalous phosphate glasses’, because magnesium is attributed to a variation of the oxygen coordination number from 6 to 4. Magnesium in phosphate glasses acts as an intermediate oxide and its role was determined, relating to the phosphate chain length. In the present work, MgO–P2O5–TiO2/Nb2O5 glasses with Mg/P ratio between 1.00 and 1.36 were successfully prepared by a melt–quenching method. Magnesium in the glasses worked as a network former to form P–O–Mg bonds, which are cross-linked short phosphate chains that improved the glass-forming ability. Intermediate oxides (i.e., TiO2 and Nb2O5) in the glasses also cross-linked short phosphate chains to form P–O–Ti/Nb bonds. The chemical durability of the glasses decreased with an increase in the Mg/P ratio, because magnesium, which entered the phosphate network, weakened the glass network to induce hydrolysis. The dissolution rate of Ti4+ and Nb5+ ions showed a decreasing tendency with an increase in the Mg/P ratio. The surfaces of the glasses were considered to be covered with gel-like oxide layers containing titanium or niobium and phosphate.


Keyword:
Biomaterial, Phosphate glass, Invert glass, Magnesium, Niobium, Titanium, Structure

Received: June 29, 2015
Accepted: July 17, 2015 , Published online: October 01, 2015

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