Nano-sized calcium-deficient apatitic (CDHA) crystals with Ca/P ratios from 1.5 to 1.67 were synthesized using wet chemical method and of needle-like shape with 5-10nm in diameter and 40-50nm in length was observed. The structural environment of the Ca atoms in all the CDHA nano-crystals has been investigated using EXAFS, XANES and EELS. The results reveal that a maximum Fourier transform amplitude occurs at the apatite with a Ca/P ratio of 1.67 and the structural disorder increase following the sequence of 1.67>1.5>1. 6>1.55. A similar phenomenon is also observed in both K-edge XANES and L 2,3-edge ELNES in the Ca atom. The structural analysis further demonstrates that different chemical and biological properties among these CDHA nano-crystals with Ca/P ratio from 1.5 to 1.67 are primarily due to the effect of stoichiometry and non-stoichiometry as compared to the structural order-disorder.
- Calcium-deficient apatites (CDHA)
- Electron energy loss spectrometry (EELS)
- Electron-energy loss near-edge structure (ELNES)
- Needle-like crystals
- X-ray absorption near-edge structure (XANES)