Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK.
J Dent. 2010 Apr;38(4):325-30. doi: 10.1016/j.jdent.2009.12.005. Epub 2010 Jan 4.
To investigate the long term setting reaction in the glass ionomer restorative, Fuji IX, by monitoring the structural evolution of aluminium and fluorine species using (27)Al and (19)F MAS-NMR spectroscopy.
Fuji IX cements aged from 5min up to 3 months were prepared according to the manufacturer instructions from the commercial material. The (27)Al and (19)F MAS-NMR studies were carried out on powders made after terminating the setting reaction.
(27)Al MAS-NMR results show conversion of aluminium from the glass phase, where it has coordination number four, Al(IV), into the cement matrix where it has a coordination number of six, Al(VI). At least two different Al(VI) species were detected at short ageing time cements. Assignment of these species is discussed and compared with the data from other sources. The possibility for a condensed aluminium species Al(13)(OH)(24)(H(2)O)(12) to form is considered. The ratio of aluminium in the cement, Al(VI), to the remaining unreacted in glass has been evaluated by deconvolution of the spectra. Various theoretical ratios of aluminium species in the cement matrix to the unreacted ones remaining in glass have been estimated. The (19)F MAS-NMR spectra are identical for the glass and cements at the early times and contain a dominant signal assigned to Al-F-Sr(n).
The data confirms that the conversion of aluminium is a diffusion-controlled process at early stage less than 1h and it is largely complete between 1 and 6h. The comparison with the experimental data shows that the majority of aluminium cations do not form tricarboxylates but are coordinated with one or two carboxylic groups and other ligands. Insufficient amount of water and excess of glass in this cement formulation affect glass degradation mechanism.
通过使用（27）Al 和（19）F MAS-NMR 光谱监测铝和氟物种的结构演变，研究玻璃离子体修复剂 Fuji IX 的长期定域反应。
根据制造商的说明，从商业材料中制备 Fuji IX 水泥，从 5 分钟到 3 个月不等。在终止凝固反应后，对粉末进行（27）Al 和（19）F MAS-NMR 研究。
（27）Al MAS-NMR 结果表明，铝从玻璃相（配位数为四，Al（IV））转化为水泥基质（配位数为六，Al（VI））。在短龄水泥中至少检测到两种不同的 Al（VI）物种。讨论了这些物种的归属，并与其他来源的数据进行了比较。考虑了形成[Al（13）（OH）（24）（H（2）O）（12）]（7+）凝聚铝物种的可能性。通过对光谱进行解卷积，评估了水泥中铝（VI）与玻璃中剩余未反应的铝（VI）的比值。估计了水泥基质中各种理论铝物种与玻璃中剩余未反应的铝（VI）的比值。在早期，玻璃和水泥的（19）F MAS-NMR 光谱相同，包含一个主要信号，分配给 Al-F-Sr（n）。
数据证实，铝的转化是一个扩散控制的过程，在早期小于 1 小时，在 1 到 6 小时之间基本完成。与实验数据的比较表明，大多数铝阳离子不形成三羧酸根，但与一个或两个羧酸基团和其他配体配位。在这种水泥配方中，水的量不足和玻璃的量过多会影响玻璃降解机制。
