This is a can of worms that keeps cropping up now and again. Rather than go into masses of detail I'd suggest looking at the Rietveld mailing list archive for some fairly detailed discussions on the subject. I'd go with Bob's route as it's applicable in a laboratory environment but foolproof it isn't and good sample preparation is vital. Pam
________________________________ From: Von Dreele, Robert B. [mailto:[EMAIL PROTECTED] Sent: Wed 27/02/2008 11:52 AM To: rietveld_l@ill.fr Subject: RE: % Crystallinity John (& others), The best way to determine %crystallinity (or %amorphous) is to do "spiking" experiments with material with known (preferably ~100%) crystallinity. The change in the apparent phase fractions by Bragg intensities as compared to that expected from the masses can be used to estimate the fraction that doesn't Bragg scatter (i.e. the amorphous content). The spiking material should also be chosen to have nearly matching absorption to avoid systematic effects (e.g. Brindley corrections). It does not have to be the same phase as the crystalline phase in your sample. There are literature references to this but I can't recall the exact ones to look at. Perhaps others might know them better. (BTW - this is not a PDF problem). Bob Von Dreele ________________________________ From: john o callaghan [mailto:[EMAIL PROTECTED] Sent: Wed 2/27/2008 5:58 AM To: rietveld_l@ill.fr Subject: % Crystallinity Dear Users, I'm trying to determine the percentage crystallinity in a crystalline/amorphous mixture, could someone point me in a foolproof direction. Thanks, John ________________________________ Free upgrade for your Windows Live Messenger! Click here! <http://get.live.com/>
<<winmail.dat>>
