X-ray determination of crystalline hydroxyapatite to amorphous calcium-phosphate ratio in plasma sprayed coatings
✍ Scribed by Keller, Ludwig ;Dollase, W. A.
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 188 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0021-9304
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✦ Synopsis
A method to measure the amorphous calcium phosphate (ACP) content of plasma sprayed hydroxyapatite (HA) coatings is presented. The areas of the crystalline peaks and the broad amorphous "hump" in an X-ray diffraction scan of a mixture of crystalline and amorphous HA can be fitted using conventional nonlinear least-squares methods. The weight fraction of the amorphous component in a mixture of unknown proportions is obtained from the measured hump fraction using a linear expression requiring a single calibration constant. This calibration constant may be determined by applying the same sample preparation, X-ray mea-surement, and least-squares fitting methods to a single standard of known (weighed) proportions as used to measure the unknown(s). Application of this method to a set of 12 samples yields an "index of crystallinity" for plasma sprayed HA coatings with an estimated standard deviation of 1 wt % ACP across the entire compositional range.