# Changeset 3055 for Tutorials

Ignore:
Timestamp:
Sep 8, 2017 1:47:41 PM (5 years ago)
Message:

update for 2 frame

Location:
Tutorials/2DTexture
Files:
51 deleted
53 edited

Unmodified
Removed
• ## Tutorials/2DTexture/Texture analysis of 2D data in GSAS-II.htm

 r2385 Von Dreele Von Dreele 10 2143 vondreele 12 2274 2015-05-14T17:06:00Z 2016-07-28T18:35:00Z 54 4339 24736 2017-09-08T18:45:00Z 47 4356 24830 Argonne National Laboratory 206 58 29017 29128 16.00 Print 124 Clean Clean mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-536870145 1073786111 1 0 415 0;} mso-font-signature:-536859905 -1073732485 9 0 511 0;} @font-face {font-family:Tahoma; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

o:title="" chromakey="white"/>  and , take on values according to the crystal and sample symmetries, respectively, and thus the two inner o:title="" chromakey="white"/>  terms are nonzero so the rest are excluded o:title="" chromakey="white"/> coefficients is sufficient to describe the effect on the diffraction patterns due to texture. The crystal o:title="" chromakey="white"/> , is defined for each reflection, h, via polar and azimuthal coordinates ( , is defined according to polar and azimuthal coordinates (y,
o:title="" chromakey="white"/>  and   tan(

o:title="" chromakey="white"/>  and , are developed from

o:title="" chromakey="white"/>

o:title="" chromakey="white"/> , are defined via a Fourier expansion as

o:title="" chromakey="white"/>

o:title="" chromakey="white"/>

o:title="" chromakey="white"/> .  These Fourier coefficients are determined so o:title="" chromakey="white"/>

o:title="" chromakey="white"/>  and  are combined depending on the symmetry and the o:title="" chromakey="white"/>  and .  For cubic crystal symmetry, the term  is obtained directly from the Fourier o:title="" chromakey="white"/>

o:title="" chromakey="white"/> , as tabulated by Bunge (1982).

o:title="" chromakey="white"/> , and the three sample orientation angles, Ws,  and the sample orientation angles

If the texture is random then J = 1, otherwise J > 1; for a single crystal J = ¥.

margin-left:0in;line-height:115%'>If the texture is random then J = 1, otherwise J > 1; for a single crystal J = ¥.

In GSAS-II the texture is defined in two ways to accommodate the two possible uses of this correction. In one a suite of to accommodate the two possible uses of this correction. In one, a suite of spherical harmonics coefficients is defined for the texture of a phase in the sample; this can have any of the possible sample symmetries and is the usual result desired for texture analysis. The other is the suite of spherical harmonics terms for cylindrical sample symmetry for each phase in each powder pattern (histogram) and is usually used to accommodate preferred orientation effects in a Rietveld refinement. The former description allows refinement of the sample orientation zeros, Ws, harmonics terms for cylindrical sample symmetry for each phase in each powder pattern (histogram) and is usually used to accommodate preferred orientation effects in a Rietveld refinement. The former description allows refinement of the sample orientation zeros, Ws, Cs, Fs, but the latter description does not (they are entries are listed in bold face below as bold face below as Help/About GSAS-II, which lists first the name of the menu (here Help) and second the name of the entry in the menu (here Help) and second the name of the entry in the menu (here About GSAS-II).

Use the Import/Image/from GE image file menu item to read the data file into the current GSAS-II project. A file selection dialog will be shown; its appearance will depend on your OS. Change the search directory to About GSAS-II).

Use the Data/Read image data menu item to read the data file into the current GSAS-II project. A file selection dialog will be shown; its appearance will depend on your OS. Change the search directory to 2DTexture/data and then select the file NDC5_01588_1.ge2. A (faint) image will appear

and the Image Controls data page will show

minor-latin;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin'>2DTexture/data and then select the file NDC5_01588_1.ge2. An image will appear

and the Image Controls data page will show

The detector was previously calibrated and the coefficients are stored in a file found by doing Operations/Load Controls from the Image Controls menu. A file selection popup will appear showing NDC5.imctrl; select it and press Open. The Parms/Load Controls from the Image Controls window will be repainted with the new values (do a reselect of the image from the tree and then Image Controls to make sure the image is up to date.)

Controls menu. A file selection popup will appear showing NDC5.imctrl; select it and press Open. The Image Controls window will be repainted with the new values and the image will be redrawn.

The detail in

For texture analysis we will need to integrate the image into a number of slices sampling the style='mso-no-proof:yes'>

For texture analysis we will need to integrate the image into a number of slices sampling the changing ring intensity with azimuthal angle. Also note that the image seems to have

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The

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It turns out

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Change the

for one ring. This level is too low. Return to the Image Controls item in the data tree.

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for one ring. This level is too low. Return to the Image Controls item in the data tree.

We are now ready to integrate the image; do Operations/Integrate from the Integration/Integrate from the Image

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0.005 for both.
Use the Data/Add mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Data/Add new phase to enter the Atoms tab begin by doing Edit/Append atom twice then fill in the Type and coordinates boxes. A double click of the Type entry will show a popup of the Periodic Table; select the element as appropriate. NB: GSAS-II happily takes 1/2 & 1/4 for coordinate values; these get converted to their decimal equivalent upon entry. Note the use of a nonstandard space group designation for B19. When done the B2 Atoms table should look like

and the B19 Atoms table should be

minor-latin;mso-hansi-theme-font:minor-latin'>Edit Atoms/Append atom
twice then fill in the Type and coordinates boxes. A double click of the Type entry will show a popup of the Periodic Table; select the element as appropriate. NB: GSAS-II happily takes 1/2 & 1/4 for coordinate values; these get converted to their decimal equivalent upon entry. Note the use of a nonstandard space group designation for B19. When done the B2 Atoms table should look like

and the B19 Atoms table should be

Next go to the tab for each phase; there will be a message indicating the lack of data for each. Do Edit/Add mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Add powder histograms, do

and that for B19 will be

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and that for B19 will be

You should now varying the phase fractions instead.

Next select the B2 phase and pick the Data tab; you will see

Next select the B2 phase and pick the Data tab; you will see

Select the box. Then do Edit/Copy data, select Set All & press OK to copy these to the other histograms. Next select the B19 phase and repeat this process. We are now ready for the first refinement; do Calculate/Refine from the main GSAS-II data tree window. A progress bar popup will appear and when done a Refinement results popup will show with Rw~32%. Press OK to load this result; GSAS-II will return you to the last window you were using and display the 1st powder pattern showing you the fit

mso-hansi-theme-font:minor-latin'>Edit Phase/Copy data
, select Set All & press OK to copy these to the other histograms. Next select the B19 phase and repeat this process. We are now ready for the first refinement; do Calculate/Refine from the main GSAS-II data tree window. A progress bar popup will appear and when done a Refinement results popup will show with Rw~32%. Press OK to load this result; GSAS-II will return you to the last window you were using and display (NB: pick the 1st PWDR entry) the 1st powder pattern showing you the fit

This is quite poor. You can survey the fit successively by 1st selecting say the 1st PWDR entry from the tree and then using the up/down arrow keys to step to the next one; the plot will redraw at each step (NB: at full scale) and the data window will show statistics of the fit. There is a substantial intensity discrepancy; this is due to the texture. It is also evident that some of the peaks are out of place relative to the reflection markers; this is due to macroscopic strain in the drawn wire. For the B2 phase select the Texture tab; it should look like

next one; the plot will redraw at each step (NB: at the same scale as the 1st one selected) and the data window will show statistics of the fit. There is a substantial intensity discrepancy; this is due to the texture. It is also evident that some of the peaks are out of place relative to the reflection markers; this is due to macroscopic strain in the drawn wire. For the B2 phase select the Texture tab; it should look like

The texture

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Then go to the

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Then do Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy flags to have

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Then go to the boxes and do Edit/Copy flags as before. The tab will look like

minor-latin'>Edit Phase/Copy flags
as before. The tab will look like

Now do

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The calculated mso-hansi-theme-font:minor-latin'>microstrain box. Then do Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy flags to set it for the other PWDR data sets. Do the same for the Calculate/Refine from the main menu. The fit will be substantially improved with Rw ~9.2%.

substantially improved with Rw ~10%.

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It is evident

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And a drawing

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This shows the

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This phase is direction. Again we want to increment the Harmonic order to the next higher level (8). Again do Calculate/Refine from the main menu; the Rwp has dropped to ~7.9%. One can add the atom Rwp has dropped to ~8.9%. One can add the atom Uiso for the Ni and Ti atoms in the B2 phase and the coordinates and Uiso for the B19 phase. The Rw drops a bit further to ~7.4%. B19 phase. The Rw drops a bit further to ~8.4%. Finally, we can increase the harmonic order again for the B19 phase (it is very strongly textured!) to 10 and the B2 phase to 12; the final refinement converged to Rw ~6.8% and the B19 inverse pole converged to Rw ~7.8% and the B19 inverse pole figure has peaks at ~18 MRD (Multiple of Random Distribution) and the B2 phase peaks are ~7MRD.

and inverse pole figure

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and inverse pole figure

The B2

and inverse pole figure

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and inverse pole figure

This completes

This begins the texture analysis in much the same way as Method A except that all the initial refinements are done sequentially, that is refinements are done for the parameters associated with each powder pattern to convergence in a serial the texture analysis in much the same way as Method A except that all the initial refinements are done sequentially, that is refinements are done for the parameters associated with each powder pattern to convergence in a serial fashion. In this case where there are 10 PWDR data sets, there will be 10 refinements done in sequence. Parameters that span all the data (e.g. lattice mso-hansi-theme-font:minor-latin'>Spherical harmonics. Then do Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy data to copy both the flag and the model to the other PWDR entries.

mso-hansi-theme-font:minor-latin'>Spherical harmonics
. Then do Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy data to copy both the flag and the model to the other PWDR entries.

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Press the

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You have the

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There is a row

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To set these v:shapes="Picture_x0020_5">

Check the D11 box under Hydrostatic/elastic strain, set the Harmonic order to 6 and check the Refine box for it (Preferred orientation). Then in two steps, do Edit/Copy flags and Set All for the file selection. Then do Edit/Copy selected data; that will bring up a new popup

Check the D11 box under Hydrostatic/elastic strain, set the Harmonic order to 6 and check the Refine box for it (Preferred orientation). Then in two steps, do Edit Phase/Copy flags and Set All for the file selection. Then do Edit Phase/Copy selected data; that will bring up a new popup

This allows you to select which parameters to copy data and flags. Select Pref. Ori. And press OK; the file selection is next. Do Set All and OK to do this copy. That copies the full spherical harmonics model to the other data sets. Select one to check if youd like.

you to select which parameters to copy data and flags. Select Pref. Ori. And press OK; the file selection is next. Do Set All and OK to do this copy. That copies the full spherical harmonics model to the other data sets. Select one to check if youd like.

Next do the same thing for the B19 phase; here there are 4 Dij parameters to check (do all of them) and use spherical harmonics order 4. When done that Data window will look like

same thing for the B19 phase; here there are 4 Dij parameters to check (do all of them) and use spherical harmonics order 4. When done that Data window will look like

We are now ready for the next refinement; do Calculate/Sequential refine. Be careful not (by habit say) pick Refine; a warning popup will appear. After it completes the Sequential refinement results shows that the fit is better but convergence wasnt quite complete.

ready for the next refinement; do Calculate/Sequential refine. Be careful not (by habit say) pick Refine; a warning popup will appear. After it completes the Sequential refinement results shows that the fit is better but convergence wasnt quite complete.

It is probably

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As our experience in Method A, the calculated peaks are too sharp. We need to vary the mustrain parameters for both phases. Go to the Data tab for each phase, check the microstrain box and do Edit/Copy flags for all the data sets. Then do another Calculate/Sequential refine. My Sequential refinement results showed great improvement but incomplete refinement

tab for each phase, check the microstrain box and do Edit Phase/Copy flags for all the data sets. Then do another Calculate/Sequential refine. My Sequential refinement results showed great improvement but incomplete refinement

Repeating the

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Examination of

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Showing that perhaps the B19 phase needs high order spherical harmonics. Select the Data tab for the B19 phase and change the Harmonic order to 6. Then do Edit/Copy selected data for Pref.Ori. to the other data sets. This (after few repeats) gives a further improvement in the fit

tab for the B19 phase and change the Harmonic order to 6. Then do Edit Phase/Copy selected data for Pref.Ori. to the other data sets. This (after few repeats) gives a further improvement in the fit

This fit is 0in;line-height:115%'>Step 2. Texture analysis

During the sequential refinements done in Step 1, we fitted the profiles allowing strain parameters (Dij) for peak position shifts and microstrain for peak shape. We modeled the intensity variation with a spherical harmonics preferred orientation correction. If you select any PWDR entry from the GSAS-II data tree and pick the Reflection List subentry (at the bottom) you can see the magnitude of this correction for each reflection in each phase.

During the sequential refinements done in Step 1, we fitted the profiles allowing strain parameters (Dij) for peak position shifts and microstrain for peak shape. We modeled the intensity variation with a spherical harmonics preferred orientation correction. If you select any PWDR entry from the GSAS-II data tree and pick the Reflection List subentry (at the bottom) you can see the magnitude of this correction for each reflection in each phase.

For the B2

and for the B19 phase we see

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and for the B19 phase we see

The preferred

Since this sample has wire texture, well use the default Texture model (cylindrical). Then set the Harmonic order to 12 (what we used earlier) and check the Refine and Show coeff boxes. The data window will be redrawn (and a blank plot will appear).

Do Texture/Refine texture from the menu; the window will be repainted and a bullseye pole figure will appear.

Change the Texture plot type to Inverse pole figure to get a more useful plot

sample has wire texture, well use the default Texture model (cylindrical). Then set the Harmonic order to 12 (what we used earlier) and check the Refine and Show coeff boxes. The data window will be redrawn (and an orange blank plot will appear).

Do Texture/Refine texture from the menu; the window will be repainted and a bullseye pole figure will appear.

Change the Texture plot type to Inverse pole figure to get a more useful plot

This is essentially the same as we obtained earlier in Method A (maybe not quite as strong here).

essentially the same as we obtained earlier in Method A (maybe not quite as strong here).

Now select the Texture tab for the B19 phase and do the same; use Harmonic order 10 as we did earlier in Method A. After setting the two flags and doing Texture/Refine texture we get

Texture tab for the B19 phase and do the same; use Harmonic order 10 as we did earlier in Method A. After setting the two flags and doing Texture/Refine texture we get

And a bullseye

Again this is very similar to what we found in Method A but again not quite as strong (max MRD ~13 instead of ~18).

Now do a File/Save project from the main menu; this saves the final texture results done in Step 2 (you also will need it for Method C).

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Again this is very similar to what we found in Method A but again not quite as strong (max MRD ~10 instead of ~18) and a bit choppier.

Now do a File/Save project from the main menu; this saves the final texture results done in Step 2 (you also will need it for Method C).

Here we want to clear refinement flags for all parameters that need not be varied in a texture analysis refinement. The general rule is to not refine any parameter unless we expect it to affect the peak intensities. These are listed below:

texture analysis refinement. The general rule is to not refine any parameter unless we expect it to affect the peak intensities. These are listed below:

Data tab. Clear the Data tab. Clear the Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy flags selecting all data to clear all the flags and an Edit/Copy selected data for Pref.Ori to copy the zeroed out harmonic coefficients.

mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy selected data for Pref.Ori to copy the zeroed out harmonic coefficients.

Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy flags selecting all data to clear all the flags and an Edit/Copy mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit Phase/Copy selected data for

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id="Picture_x0020_109" o:spid="_x0000_i1030" type="#_x0000_t75" style='width:468pt; height:177pt;visibility:visible;mso-wrap-style:square'>

Texture tab. Set the Set the Harmonic order to zero and then

In this case you do want to do a nonsequential full refinement, so press the OK button. A quick look at the console will show that there are 61 variables in this refinement. If yours shows more then you didnt clear all the flags in Step 1. The

In this case you do want to do a nonsequential full refinement, so press the OK button. A quick look at the console will show that there are 61 variables in this refinement. If yours shows more then you didnt clear all the flags in Step 1. The Sequential results entry is

which is almost identical to that from Method A. The style='mso-no-proof:yes'>

which is almost identical to that from Method A. The coefficients are seen in

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Now select the

and also almost identical to what was obtained in Method A; the coefficients are seen in

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and also almost identical to what was obtained in Method A; the coefficients are seen in

With this

• ## Tutorials/2DTexture/Texture analysis of 2D data in GSAS-II_files/filelist.xml

 r1856
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