# XRD nano-hydroxyapatite

1. Sep 23, 2009

### Msl

Hello!

I would like to ask your help in the interpretation of Xrd data from hydroxyapatite nanopowder.
I know from the start that powders which I am analysing are already crystalline (another techniques were used to confirme that) but I keep having a characteristic spectrum of amorphous hydroxyapatite.
Why does this happen? What´s the influence of crystal size during in XRD procedure?

Thank you !

2. Sep 23, 2009

### Dave_H

Hello,
A small crystal size will induce a broadening effect of the Debye rings. This relationship is discribed by:

B=0.9$$\lambda$$/tcos($$\theta$$)

B = broadening of diffraction line measure at FWHM
t = crystal size diameter

B is the broadening of the peak due to grain size alone, therefore you must correct for the specific machine, do this using a large grained standard (of the same material).

B2 = BM2 - Bs2
Where BM is the measured breadth of the diffraction line and Bs is the measured breadth of the of the standard line.

I hope this helps, all this info can be found with much better explanation in:

Elements of X-Ray Diffraction, 2nd Edition, B.D. Cullity

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