mabied
Hi
I am beginner in using TOPAS-Academic, so I wonder if anyone can send me practical example for doing micro-structure analysis (Crystallite size, microstrain)) of a powder patterns using topas.
Thanks
Mabied
mabied
I have learned to do it, just I wonder if possible to know the direction of the obtained strain using hkl, d ..etc
Thanks
Mabied
rowlesmr
mabied
Thanks, it sound useful :-)
Best Regards
Mabied
jadebressnan
Analysis is very important everywhere and there are many benefits that we can get from doing an Analysis of a micro structure.Also some data and information that is needed for that.
fgispert
Dear all,
I'm trying to find the units used in TOPAS for microstrain. I can't find the units employed for e0 parameter calculated by the macro e0_from_Strain(...). I think that the units employed are in % but I'm not sure. Can anyone help me?
Thanks a lot,
Francesc
alancoelho
The e0 in the e0_from_Strain macro is defined as:
e0 = Voigt_FWHM_GL(Strain_G_prm, Strain_L_prm) / 4
Voigt_FWHM_GL gives a FWHM of a Voigt in 2Th degrees as the Strain_G and Strain_L macros are in 2Th degrees. To convert to strain (as a ratio as per the definition of strain) then multiply by Pi/360. Thus
e0 as a strain ratio (ie. delte_d/d) = e0_from_Strain Pi/360
Also, Reprints of Balzar's work can be downloaded from:
http://www.ccp14.ac.uk/ccp/web-mirrors/balzar/div853/balzar/research.htm
alancoelho
Just a reminder that the e0_from_Strain macro has been modified to include the Pi/360 scaling constant for Version 5 with all current Version 5 users being updated and informed of the change.
alhansen
Dear all,
I'm wonderung what happened to the e0_from_Strain macro in Version 6. I used my Version 5 inp file, fixed all the variables to ensure the're the same in both versions. Yet, the values of e0 are extremely different. although the values of Strain_L and Strain_G are the same.
from the log file:
Version 5: prm = Voigt_FWHM_GL((!sgc), (!slc)) .25 3.14159265358979/360; : 0.09029`_0.00152 prm !sgc 0.26525`_0.00502 gauss_fwhm = (!sgc) Tan(Th); prm !slc 0.15881`_0.00549 lor_fwhm = (!slc) Tan(Th);
and Version 6: prm = Voigt_FWHM_GL((!sgc), (!slc)) .25 3.14159265358979/360; : 0.00079 prm !sgc 0.26525_0.00502 gauss_fwhm = (!sgc) Tan(Th); prm !slc 0.15881_0.00549 lor_fwhm = (!slc) Tan(Th);
Actually, this leaves me a little confused.
Best,
Anna
alancoelho
Hi Anna
There's a Pi/360 difference between the two values for e0. Are you sure the output you supplied are from the same program. The e0_from_Strain macro should look like:
macro e0_from_Strain(e0, sgc, sgv, slc, slv)
{
#m_argu sgc
#m_argu slc
prm = Voigt_FWHM_GL(CeV_or_0(sgc, sgv), CeV_or_0(slc, slv)) .25 Pi/360; : e0
#m_ifarg sgv "" #m_else
Strain_G(sgc, sgv)
#m_endif
#m_ifarg slv "" #m_else
Strain_L(slc, slv)
#m_endif
}
In general the value of e0*360/pi() should be in the same ball park as sgc and slc. V6 seems to be doing the right thing.
Having said the above I think the Version 5 TOPAS.INC may not have contained the fix. Can you check please that your TOPAS.INC has the above macro and let me know.
cheers
alan
alhansen
Dear Alan,
thank you for your answer! It helped me alot. The macro in the topas.inc of my Version 6 looks exactly like yours:
macro e0_from_Strain(e0, sgc, sgv, slc, slv)
{
#m_argu sgc
#m_argu slc
prm = Voigt_FWHM_GL(CeV_or_0(sgc, sgv), CeV_or_0(slc, slv)) .25 Pi/360; : e0
#m_ifarg sgv "" #m_else
Strain_G(sgc, sgv)
#m_endif
#m_ifarg slv "" #m_else
Strain_L(slc, slv)
#m_endif
}
I'll check it for our other Topas Versions as well...
Best,
Anna
mynam22
Hi
I am using Topas Academic V5. Recently we had to re-install it on a new computer. There is an issue that I'd like to find the answer to.
When I run my old scripts on the new software, I get different values for strain (e0_from_Strain), it would change from 0.00125 to 0.14336. Based on what I have read here, I realized that there has been an update on V5 several years ago. I just want to make sure that when I multiply the strain output in the new software by PI/360, I will get delte_d/d value. I appreciate your help.
Thank you