Abstract
The stability of yttrium silicate apatite has been investigated by studying the influence of iron as a "stabilising cation" and also by using different synthesis routes. The formation of apatite in samples has been followed by X-ray diffraction and by 29Si MAS NMR spectroscopy. The apatite phase appears to be stable at high temperatures (≈1700°C) especially when heated in a nitrogen atmosphere; it can also occur in a metastable state when heated in air at lower temperatures; ≈1600°C if prepared from a Y2O3-SiO2 mixture or in the range 950°C < T < 1150°C if synthesised by the sol-gel process. Longer heat-treatments result in its decomposition into Y2Si2O7 and Y2SiO5. Iron appears to have two roles depending on the temperature; it stabilises the apatite phase at high temperatures when produced by the sol-gel route and catalyses the decomposition of sol-gel derived apatite at low temperatures.
Original language | English |
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Pages (from-to) | 495-502 |
Number of pages | 8 |
Journal | Solid State Sciences |
Volume | 3 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2001 |