Shape change and phase transition of needle-like non-stoichiometric apatite crystals
✍ Scribed by L. Yubao; C. P. A. T. Klein; J. Wijn; S. Meer; K. Groot
- Publisher
- Springer
- Year
- 1994
- Tongue
- English
- Weight
- 983 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0957-4530
No coin nor oath required. For personal study only.
✦ Synopsis
Nanometre-size needle-like non-stoichiometric apatite crystals are made in our laboratory by hydrothermal treatment at 140°C at a pressure of 0.3 MPa for 2 h. The shape change and phase transition of these crystals are studied using transmission electron microscopy (TEM), X-ray diffractometer (XRD) and infrared spectroscopy (IR). The results show that water molecules are present in the crystal structure of non-stoichiometric apatite. The condensation of HP042-ions can happen over a wide temperature range more than 600°C and is followed closely by the reaction of P20 4-ions with OH-ions. The obvious TCP phase at 750°C is the outcome of the fusion and recrystallization of the needle-like crystals at 650 °C and 750 °C. Generally, stoichiometric apatite cannot contain water in its crystal structure while non-stoichiometric apatite can. Maybe this is the reason why bone contains non-stoichiometric apatite.