Dear Ed,
you need to take the cos(theta) instead of the sin(theta)..... Of course
you have to consider the instrumental resolution, otherwise you
underestimate size.
Good recovery (or what you say in English...)
Andreas Leineweber
Edward Laitila wrote:
Stephen,
The peak profile gives information about the crystallite or coherent
diffracting domain size along with microstrain. You cannot not get a grain size
unless the crystallite size can be related to the grain size from knowledge of
the microstructure. The crystallite size can be estimated using the Scherrer
equation assuming no microstrains and a spherical shape. The equation is the
thickness or size = (0.9 X lambda)/(breadth(radians) X sin(theata)), that is if
I remember correctly since I am currently in the hospital. I hope this helps, a
rather simple calculation that provides a good estimate. I should note there
are correction schemes of gaussian and lorentzian (I normally use a geometric
mean of the two) that is important when the breadth is only a couple of
hundreds or less (please see B.D. Cullity Elements of X-Ray Diffraction in my
opinion one of the best XRD references). Also the values change with angle so I
typically have found averaging the values of the 5 lowest an!
gl!
e peaks is close to the Warren-Averbach results.
Cheers,
Ed
----- Original Message -----
From: [EMAIL PROTECTED]
To: "Rietveld L" <Rietveld_L@ill.fr>
Sent: Wednesday, November 12, 2008 5:42:37 AM GMT -05:00 US/Canada Eastern
Subject: Suggestion about software(s) for size profile-broadening calculation
Dear all experts in XRD,
As stated in the header, does anyone know if there is some software(s)
available for estimation of average crystal grain size using the peak
breath of XRD data? I just want to know some rough values so as to
compare my samples prepared at different conditions. Many thanks for
your kind helps.
Great appreciate.
stephen
