[GSAS-II] Regarding dislocation density calculation using crystallite size and microstrain

[Toby, Brian H.]

For the list archives, Bob’s reply:

Dear Sorb,
GSAS-II reports microstrain values as 10^-6 strain. To give 10^-3 values, simply divide the GSAS-II values by 1000.
Bob

On Jun 8, 2023, at 12:55 AM, Sorub via GSAS-II <gsas-ii at aps.anl.gov> wrote:

Dear Brian,
I am a regular user of HPCAT beamline, APS.

I want to calculate the dislocation density of silicon phases. I need to include both microstrain and domain size contributions in the equation.
As we know,
Dislocation density, ρd = (ρD * ρS)1/2
Contribution from domain size (D), ρD = 3/D2
Contribution from microstrain, ρS = k(εl)2/b2
εl  is equivalent to the average microstrain
In this equation, the microstrain calculations reported in the literature are of the order of 10-3
In GSAS II, the microstrain is of the order of 106
Do we need any conversion factor to calculate the microstrain to make it to the order of 10-3? Otherwise, we will overestimate the dislocation density
The Williamson-Hall plot gives the microstrain of the Si ambient phase of the order 10-3
Please provide your valuable suggestions to tackle this issue
Thanks
Regards
Sorb Y A
Iowa State University
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