Ignore:
Timestamp:
Apr 21, 2018 7:30:01 PM (5 years ago)
Author:
toby
Message:

update profile params generation tutorial

File:
1 edited

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  • Tutorials/CWInstDemo/FindProfParamCW.htm

    r3342 r3354  
    2525  <o:Author>Brian Toby</o:Author>
    2626  <o:LastAuthor>Brian Toby</o:LastAuthor>
    27   <o:Revision>4</o:Revision>
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    29   <o:Created>2018-04-12T21:09:00Z</o:Created>
    30   <o:LastSaved>2018-04-12T21:19:00Z</o:LastSaved>
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     27  <o:Revision>3</o:Revision>
     28  <o:TotalTime>302</o:TotalTime>
     29  <o:Created>2018-04-21T19:50:00Z</o:Created>
     30  <o:LastSaved>2018-04-21T19:51:00Z</o:LastSaved>
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    694710<div class=WordSection1>
    695711
    696 <h1>Determining Profile Parameters from a Standard</h1>
     712<h1><span style='mso-bidi-font-family:"Times New Roman"'>Determining Profile
     713Parameters from a Standard<o:p></o:p></span></h1>
    697714
    698715<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    745762<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    746763
    747 <h3><span style='font-size:14.0pt'>Step 2: Select Default Instrument Parameters<o:p></o:p></span></h3>
     764<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     7652: Select Default Instrument Parameters<o:p></o:p></span></h3>
    748766
    749767<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    816834normal'>Click on the Limits</b> data tree item, and either change the <span
    817835class=SpellE>Tmin</span> value from 10 to 20 or in the plot <b
    818 style='mso-bidi-font-weight:normal'>ÒdragÓ the green line to the right</b> to approximately
    819 20 degrees. <o:p></o:p></span></p>
     836style='mso-bidi-font-weight:normal'>ÒdragÓ the green line to the right</b> to
     837approximately 20 degrees. <o:p></o:p></span></p>
    820838
    821839<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
    … …  
    829847<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    830848
    831 <h3><span style='font-size:14.0pt'>Step 4: Add Peaks to Fit<o:p></o:p></span></h3>
     849<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     8504: Add Peaks to Fit<o:p></o:p></span></h3>
    832851
    833852<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    834853
    835854<p class=MsoNormal><span style='font-size:14.0pt'>To define peaks, <b
    836 style='mso-bidi-font-weight:normal'>click on the ÒPeak List</b>Ó data tree item.
    837 Note that as below, the peak list is initially empty. <o:p></o:p></span></p>
     855style='mso-bidi-font-weight:normal'>click on the ÒPeak List</b>Ó data tree
     856item. Note that as below, the peak list is initially empty. <o:p></o:p></span></p>
    838857
    839858<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
    … …  
    868887style='font-size:14.0pt'> in the pattern. Note that if a peak is entered in the
    869888wrong place <span class=GramE>it can be moved by ÒdraggingÓ it with the mouse</span>,
    870 or use a right-click to delete it. Be careful to make sure two peaks are not entered
    871 in the same place by accident<span class=GramE>,.</span><o:p></o:p></span></p>
     889or use a right-click to delete it. Be careful to make sure two peaks are not
     890entered in the same place by accident<span class=GramE>,.</span><o:p></o:p></span></p>
    872891
    873892<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
    … …  
    891910<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    892911
    893 <h3><span style='font-size:14.0pt'>Step 5: Refine Peak Areas<o:p></o:p></span></h3>
     912<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     9135: Refine Peak Areas<o:p></o:p></span></h3>
    894914
    895915<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    896916
    897917<p class=MsoNormal><span style='font-size:14.0pt'>By default, the peak
    898 intensities <span class=GramE>are flagged as to be varied</span>, but not any
    899 of the other parameters. It is wise to refine them all, but we want to make
    900 sure the parameters have a chance to converge one step at a time and we should
    901 start with only the intensities.<span style="mso-spacerun:yes">&nbsp;
    902 </span>Use the <b style='mso-bidi-font-weight:normal'>Peak Fitting/<span
    903 class=SpellE>Peakfit</span></b> menu item to perform a peak refinement. You
    904 will be asked for a name to save the project (enter a name such as <span
    905 class=SpellE>peakfit.gpx</span> and press Save). The peaks are then fit, here
    906 optimizing only the intensity values. The console window shows the details of
    907 the refinement:<o:p></o:p></span></p>
     918intensities <span class=GramE>are flagged as to be varied</span>, but not any of
     919the other parameters. It is wise to refine them all, but we want to make sure
     920the parameters have a chance to converge one step at a time and we should start
     921with only the intensities.<span style="mso-spacerun:yes">&nbsp; </span>Use the <b
     922style='mso-bidi-font-weight:normal'>Peak Fitting/<span class=SpellE>Peakfit</span></b>
     923menu item to perform a peak refinement. You will be asked for a name to save
     924the project (enter a name such as <span class=SpellE>peakfit.gpx</span> and
     925press Save). The peaks are then fit, here optimizing only the intensity values.
     926The console window shows the details of the refinement:<o:p></o:p></span></p>
    908927
    909928<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    917936style='font-size:14.0pt'><o:p></o:p></span></p>
    918937
    919 <p class=MsoNormal><span style='font-size:14.0pt'>The warning at the end is
    920 because the default peak parameters describe a peak shape that is significantly
    921 sharper than what is actually present for these data; the step size is actually
    922 fine. This warning will later go away, but if it did not this would indicate
    923 that it would be better to recollect the data with a step size decreased by a
    924 factor of 3-4. <o:p></o:p></span></p>
    925 
    926 <p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    927 
    928 <h3><span style='font-size:14.0pt'>Step 6: Refine peak areas and heights<o:p></o:p></span></h3>
     938<p class=MsoNormal><span style='font-size:14.0pt'>The warning at the end is because
     939the default peak parameters describe a peak shape that is significantly sharper
     940than what is actually present for these data; the step size is actually fine.
     941This warning will later go away, but if it did not this would indicate that it
     942would be better to recollect the data with a step size decreased by a factor of
     9433-4. <o:p></o:p></span></p>
     944
     945<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     946
     947<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     9486: Refine peak areas and heights<o:p></o:p></span></h3>
    929949
    930950<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    973993<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    974994
    975 <h3><span style='font-size:14.0pt'>Step 7: Refine peak areas, heights and
    976 widths (optional)<o:p></o:p></span></h3>
     995<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     9967: Refine peak areas, heights and widths (optional)<o:p></o:p></span></h3>
    977997
    978998<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    9851005style='mso-bidi-font-weight:normal'>Peak Fitting/<span class=SpellE>Peakfit</span></b>
    9861006menu item to start peak refinement. The results in the console window are as
    987 below. <span style="mso-spacerun:yes">&nbsp;</span>This is being done here just
     1007below.<span style="mso-spacerun:yes">&nbsp; </span>This is being done here just
    9881008to see how the individual peaks vary before we fit them with a parametric
    9891009equation. This step is not necessary, but provides a useful graphical reference
    990 to look for any anomalous peaks that one might not want to use. <span
    991 style="mso-spacerun:yes">&nbsp;</span><o:p></o:p></span></p>
     1010to look for any anomalous peaks that one might not want to use.<span
     1011style="mso-spacerun:yes">&nbsp; </span><o:p></o:p></span></p>
    9921012
    9931013<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    10011021<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    10021022
    1003 <h3><span style='font-size:14.0pt'>Step 8: Add more Background terms<o:p></o:p></span></h3>
     1023<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     10248: Add more Background terms<o:p></o:p></span></h3>
    10041025
    10051026<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    10611082<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    10621083
    1063 <h3><span style='font-size:14.0pt'>Step 9: Refine Profile Parameters<o:p></o:p></span></h3>
     1084<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     10859: Refine Profile Parameters<o:p></o:p></span></h3>
    10641086
    10651087<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    11251147also quite well fit now. <o:p></o:p></span></p>
    11261148
    1127 <h3><span style='font-size:14.0pt'>Step 10: Save the Profile Parameters<o:p></o:p></span></h3>
     1149<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     115010: Save the Profile Parameters<o:p></o:p></span></h3>
    11281151
    11291152<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
    11471170independently again, as shown in the next section. <o:p></o:p></span></p>
    11481171
    1149 <h3><span style='font-size:14.0pt'>Step 11: Plot Profile Parameters with
    1150 Individual Peak Widths (optional)<o:p></o:p></span></h3>
     1172<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     117311: Plot Profile Parameters with Individual Peak Widths (optional)<o:p></o:p></span></h3>
    11511174
    11521175<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
    … …  
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    11641187
    11651188<p class=MsoNormal><span style='font-size:14.0pt'>In the <b style='mso-bidi-font-weight:
    … …  
    11691192
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    11751198
    11761199<p class=MsoNormal><span class=GramE><span style='font-size:14.0pt'>and</span></span><span
    … …  
    11841207
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    11901213
    11911214<p class=MsoNormal><span style='font-size:14.0pt'>The displayed lines and
    … …  
    11931216widths are in red and their convolution (total broadening) is shown in blue: <o:p></o:p></span></p>
    11941217
    1195 <p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
     1218<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
    11961219style='font-size:14.0pt;font-family:Symbol;mso-fareast-font-family:Symbol;
    11971220mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'>á<span
    … …  
    12031226is exactly the same as the Gaussian so the blue curve hides the red one. <o:p></o:p></span></p>
    12041227
    1205 <p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
     1228<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
    12061229style='font-size:14.0pt;font-family:Symbol;mso-fareast-font-family:Symbol;
    12071230mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'>á<span
    … …  
    12121235from this instrument is significantly greater than the default</span> values. <o:p></o:p></span></p>
    12131236
    1214 <p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
     1237<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
    12151238style='font-size:14.0pt;font-family:Symbol;mso-fareast-font-family:Symbol;
    12161239mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'>á<span
    12171240style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span></span><![endif]><b
    1218 style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt'>Plus signs
    1219 (points):</span></b><span style='font-size:14.0pt'> these are the widths for
    1220 the individual reflections unconstrained. Note that they agree well with the
    1221 fitted curves (dashed lines).<span style="mso-spacerun:yes">&nbsp; </span><o:p></o:p></span></p>
     1241style='mso-bidi-font-weight:normal'><span style='font-size:14.0pt'>Plus signs (points):</span></b><span
     1242style='font-size:14.0pt'> these are the widths for the individual reflections
     1243unconstrained. Note that they agree well with the fitted curves (dashed
     1244lines).<span style="mso-spacerun:yes">&nbsp; </span><o:p></o:p></span></p>
     1245
     1246<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1247
     1248<p class=MsoNormal><i style='mso-bidi-font-style:normal'><span
     1249style='font-size:14.0pt'>These profile terms are more than adequate for most structural
     1250fitting problems, but it should be noted that these values are not sufficient
     1251to obtain quantitative measurements of <span class=SpellE>microstrain</span> and/or
     1252crystallite size. To obtain even better terms the instrument profile is best
     1253determined by a Rietveld fit for (with a standard where <span class=SpellE>microstrain</span>
     1254and size are known to be negligible or at least have certified values) Those certified
     1255values should be set as input values and not refined to allow U, V, W, X, and Y
     1256to be further refined. Ideally, in addition to higher angle data, the sample would
     1257also have lower angle peaks and SH/L can also be refined. <o:p></o:p></span></i></p>
     1258
     1259<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1260
     1261<h1>Part 2: Test the Profile Parameters</h1>
     1262
     1263<p class=MsoNormal><o:p>&nbsp;</o:p></p>
     1264
     1265<p class=MsoNormal><span style='font-size:14.0pt'>The obvious question will be
     1266how well do these parameters fit the data? To test this, we can start a new refinement
     1267using these parameters and see how well they do. <o:p></o:p></span></p>
     1268
     1269<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1270
     1271<p class=MsoNormal><span class=Heading3Char><span style='font-size:14.0pt'>Step
     12722.1: Read in the Diffraction Data</span></span><span style='font-size:14.0pt'><o:p></o:p></span></p>
     1273
     1274<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1275
     1276<p class=MsoNormal style='mso-pagination:none;tab-stops:28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt;
     1277mso-layout-grid-align:none;text-autospace:none'><span style='font-size:14.0pt'>Use
     1278File/New Project to create an empty project. You can say <span class=GramE>Yes</span>
     1279to the prompt to save the current project (No would not hurt.) As before, <span
     1280class=GramE>use <b style='mso-bidi-font-weight:normal'>Import/Powder Data/from <span
     1281class=SpellE>Brucker</span> RAW file</b> to read <span style='font-family:Courier'>file</span></span></span><span
     1282style='font-size:14.0pt;font-family:Courier'> </span><span style='font-size:
     128314.0pt;font-family:Courier;mso-bidi-font-family:"Menlo Regular";color:black;
     1284mso-fareast-language:EN-US'>LaB6_Jan2018.raw</span><span style='font-size:14.0pt;
     1285font-family:"Menlo Regular";color:black;mso-fareast-language:EN-US'> </span><span
     1286style='font-size:14.0pt'>from the Tutorials <span class=SpellE>CWInstDemo</span>/data
     1287directory (downloaded already from <a
     1288href="https://subversion.xray.aps.anl.gov/pyGSAS/Tutorials/CWInstDemo/data/">https://subversion.xray.aps.anl.gov/pyGSAS/Tutorials/CWInstDemo/data/</a>).
     1289After selecting this file, answer yes to ÒIs this the file you want?Ó<o:p></o:p></span></p>
     1290
     1291<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1292
     1293<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step
     12942.2: Select New Instrument Parameters<o:p></o:p></span></h3>
     1295
     1296<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1297
     1298<p class=MsoNormal><span style='font-size:14.0pt'>The next dialog to appear is
     1299titled, ÒChoose inst. <span class=SpellE>Param</span> file for LaB6_Jan2018.raw
     1300Scan 1 unlike before, we do have profile terms to read, from the file created
     1301in Step 10, above. Select the file written before (such as &lt;<span
     1302class=SpellE><i style='mso-bidi-font-style:normal'>MyInstrument</i></span><i
     1303style='mso-bidi-font-style:normal'>&gt;</i>20-<span class=GramE>70deg.instparm )</span>
     1304and <b style='mso-bidi-font-weight:normal'>press OK</b>. <span
     1305style="mso-spacerun:yes">&nbsp;</span>Note that you may need to change the file
     1306filter to see files of <span class=GramE>type .<span class=SpellE>instparm</span></span>.
     1307<o:p></o:p></span></p>
     1308
     1309<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1310
     1311<p class=MsoNormal><span style='font-size:14.0pt'>At present, the instrument
     1312type is not saved, so go to the Sample Parameters data tree item for the new
     1313histogram and change the <b style='mso-bidi-font-weight:normal'>Diffractometer
     1314type</b> from Debye-<span class=SpellE>Scherrer</span> <b style='mso-bidi-font-weight:
     1315normal'>to Bragg-Brentano</b>.<o:p></o:p></span></p>
     1316
     1317<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1318
     1319<p class=MsoNormal><span style='font-size:14.0pt'>(<span class=GramE>before</span>)<o:p></o:p></span></p>
     1320
     1321<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1322mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_24" o:spid="_x0000_i1070"
     1323 type="#_x0000_t75" style='width:377pt;height:183pt;visibility:visible;
     1324 mso-wrap-style:square'>
     1325 <v:imagedata src="FindProfParamCW_files/image047.png" o:title=""/>
     1326</v:shape><![endif]--><![if !vml]><img border=0 width=379 height=185
     1327src="FindProfParamCW_files/image048.png" v:shapes="Picture_x0020_24"><![endif]></span><span
     1328style='font-size:14.0pt'><o:p></o:p></span></p>
     1329
     1330<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1331
     1332<p class=MsoNormal><span style='font-size:14.0pt'>(<span class=GramE>after</span>)<o:p></o:p></span></p>
     1333
     1334<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1335mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_25" o:spid="_x0000_i1069"
     1336 type="#_x0000_t75" style='width:372pt;height:83pt;visibility:visible;
     1337 mso-wrap-style:square'>
     1338 <v:imagedata src="FindProfParamCW_files/image049.png" o:title=""/>
     1339</v:shape><![endif]--><![if !vml]><img border=0 width=374 height=85
     1340src="FindProfParamCW_files/image050.png" v:shapes="Picture_x0020_25"><![endif]></span><span
     1341style='font-size:14.0pt'><o:p></o:p></span></p>
     1342
     1343<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.3:
     1344Add Phase<o:p></o:p></span></h3>
     1345
     1346<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1347
     1348<p class=MsoNormal><span style='font-size:14.0pt'>We will add a phase for <span
     1349class=GramE>LaB6,</span> since this is a simple material we will input this by
     1350hand rather than trying to import it. <b style='mso-bidi-font-weight:normal'>Use
     1351Data/Add new phase</b> to create a new phase. <b style='mso-bidi-font-weight:
     1352normal'>Enter any name</b> you choose, though LaB6 is a good choice and <b
     1353style='mso-bidi-font-weight:normal'>press OK</b>. <o:p></o:p></span></p>
     1354
     1355<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1356
     1357<p class=MsoNormal><span style='font-size:14.0pt'>The symmetry and cell need to
     1358be edited on the new phaseÕs General tab. <b style='mso-bidi-font-weight:normal'>Click
     1359on the Space Group Button</b> (which defaults to P1) and <b style='mso-bidi-font-weight:
     1360normal'>enter P m -3 m</b> (note use of spaces to separate symmetry axes &#8211;
     1361though in this case since this is a standard setting, omitting the spaces works
     1362too. <span class=GramE>The space group symmetry information is displayed</span>,
     1363<span class=GramE><b style='mso-bidi-font-weight:normal'>click OK</b></span>. <o:p></o:p></span></p>
     1364
     1365<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1366mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_26" o:spid="_x0000_i1068"
     1367 type="#_x0000_t75" style='width:191pt;height:246pt;visibility:visible;
     1368 mso-wrap-style:square'>
     1369 <v:imagedata src="FindProfParamCW_files/image051.png" o:title=""/>
     1370</v:shape><![endif]--><![if !vml]><img border=0 width=193 height=248
     1371src="FindProfParamCW_files/image052.png" v:shapes="Picture_x0020_26"><![endif]></span><span
     1372style='font-size:14.0pt'><o:p></o:p></span></p>
     1373
     1374<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1375
     1376<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
     1377style='font-size:14.0pt'>Change the lattice constant</span></b><span
     1378style='font-size:14.0pt'> (<i style='mso-bidi-font-style:normal'>a</i>) from
     13791.0 to <b style='mso-bidi-font-weight:normal'>4.15689</b> A. (The value for SRM
     1380660b)<o:p></o:p></span></p>
     1381
     1382<p class=MsoNormal><span style="mso-spacerun:yes">&nbsp;</span><span
     1383style='font-size:14.0pt;mso-fareast-language:EN-US;mso-no-proof:yes'><!--[if gte vml 1]><v:shape
     1384 id="Picture_x0020_38" o:spid="_x0000_i1067" type="#_x0000_t75" style='width:5in;
     1385 height:135pt;visibility:visible;mso-wrap-style:square'>
     1386 <v:imagedata src="FindProfParamCW_files/image053.png" o:title=""/>
     1387</v:shape><![endif]--><![if !vml]><img border=0 width=362 height=137
     1388src="FindProfParamCW_files/image054.png" v:shapes="Picture_x0020_38"><![endif]></span><span
     1389style='font-size:14.0pt'><o:p></o:p></span></p>
     1390
     1391<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1392
     1393<p class=MsoNormal><span style='font-size:14.0pt'>Finally add atoms to the
     1394phase by <b style='mso-bidi-font-weight:normal'>clicking on the Atoms</b> <b
     1395style='mso-bidi-font-weight:normal'>tab</b>. Use the <b style='mso-bidi-font-weight:
     1396normal'>Edit Atoms/Append atom</b> menu item to insert an atom. A new atom is
     1397included in the table.<o:p></o:p></span></p>
     1398
     1399<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1400mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_29" o:spid="_x0000_i1066"
     1401 type="#_x0000_t75" style='width:505pt;height:71pt;visibility:visible;
     1402 mso-wrap-style:square'>
     1403 <v:imagedata src="FindProfParamCW_files/image055.png" o:title=""/>
     1404</v:shape><![endif]--><![if !vml]><img border=0 width=507 height=73
     1405src="FindProfParamCW_files/image056.png" v:shapes="Picture_x0020_29"><![endif]></span><span
     1406style='font-size:14.0pt'><o:p></o:p></span></p>
     1407
     1408<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
     1409style='font-size:14.0pt'>Double-Click</span></b><span style='font-size:14.0pt'>
     1410on the <b style='mso-bidi-font-weight:normal'>Type</b> value (H) and which
     1411opens a periodic table window. Click on the <b style='mso-bidi-font-weight:
     1412normal'>arrow next to La</b> to bring up a menu of the defined valences<o:p></o:p></span></p>
     1413
     1414<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1415mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_30" o:spid="_x0000_i1065"
     1416 type="#_x0000_t75" style='width:94pt;height:106pt;visibility:visible;
     1417 mso-wrap-style:square'>
     1418 <v:imagedata src="FindProfParamCW_files/image057.png" o:title=""/>
     1419</v:shape><![endif]--><![if !vml]><img border=0 width=96 height=108
     1420src="FindProfParamCW_files/image058.png" v:shapes="Picture_x0020_30"><![endif]></span><span
     1421style='font-size:14.0pt'><span style="mso-spacerun:yes">&nbsp;</span><o:p></o:p></span></p>
     1422
     1423<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
     1424style='font-size:14.0pt'>Select La</span></b><span style='font-size:14.0pt'> (neutral
     1425atoms are usually preferred) from that pull-down and the period table window
     1426closes. This atom is located at position 0,0,0 so no further editing is needed.
     1427For completeness add the second by using the <b style='mso-bidi-font-weight:
     1428normal'>Edit Atoms/Append atom</b> menu item again. <span class=GramE>to</span>
     1429insert an atom. For the second atom, change the type to boron by <b
     1430style='mso-bidi-font-weight:normal'>Double-Clicking</b> on the <b
     1431style='mso-bidi-font-weight:normal'>Type</b> value (H) and selecting B (the
     1432only choice) from the pull-down. The coordinates for this atom are 0.1975,0.5,0.5
     1433so the x, y and z values must be edited.<o:p></o:p></span></p>
     1434
     1435<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1436mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_31" o:spid="_x0000_i1064"
     1437 type="#_x0000_t75" style='width:513pt;height:56pt;visibility:visible;
     1438 mso-wrap-style:square'>
     1439 <v:imagedata src="FindProfParamCW_files/image059.png" o:title=""/>
     1440</v:shape><![endif]--><![if !vml]><img border=0 width=515 height=58
     1441src="FindProfParamCW_files/image060.png" v:shapes="Picture_x0020_31"><![endif]></span><span
     1442style='font-size:14.0pt'><o:p></o:p></span></p>
     1443
     1444<p class=MsoNormal><span style='font-size:14.0pt'>Note that the site multiplicities
     1445indicate that the stoichiometry is La<sub>1</sub>B<sub>6</sub>, as is expected.<o:p></o:p></span></p>
     1446
     1447<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1448
     1449<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.4:
     1450Link Histogram and Phase<o:p></o:p></span></h3>
     1451
     1452<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1453
     1454<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
     1455style='font-size:14.0pt'>Click</span></b><span style='font-size:14.0pt'> on the
     1456<b style='mso-bidi-font-weight:normal'>Data tab</b> for the phase. Note that there
     1457are no associated histograms:<o:p></o:p></span></p>
     1458
     1459<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1460mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_35" o:spid="_x0000_i1063"
     1461 type="#_x0000_t75" style='width:626pt;height:125pt;visibility:visible;
     1462 mso-wrap-style:square'>
     1463 <v:imagedata src="FindProfParamCW_files/image061.png" o:title=""/>
     1464</v:shape><![endif]--><![if !vml]><img border=0 width=628 height=127
     1465src="FindProfParamCW_files/image062.png" v:shapes="Picture_x0020_35"><![endif]></span><span
     1466style='font-size:14.0pt'><o:p></o:p></span></p>
     1467
     1468<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1469
     1470<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1471normal'>Edit Phase/Add Powder Histogram</b> menu command. <b style='mso-bidi-font-weight:
     1472normal'>Select</b> the one histogram and <b style='mso-bidi-font-weight:normal'>press
     1473OK</b>. <span style="mso-spacerun:yes">&nbsp;</span><o:p></o:p></span></p>
     1474
     1475<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1476mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_36" o:spid="_x0000_i1062"
     1477 type="#_x0000_t75" style='width:250pt;height:190pt;visibility:visible;
     1478 mso-wrap-style:square'>
     1479 <v:imagedata src="FindProfParamCW_files/image063.png" o:title=""/>
     1480</v:shape><![endif]--><![if !vml]><img border=0 width=252 height=192
     1481src="FindProfParamCW_files/image064.png" v:shapes="Picture_x0020_36"><![endif]></span><span
     1482style='font-size:14.0pt'><o:p></o:p></span></p>
     1483
     1484<p class=MsoNormal><span style='font-size:14.0pt'>Nothing needs to be changed
     1485of the new parameters added here:<o:p></o:p></span></p>
     1486
     1487<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1488mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_37" o:spid="_x0000_i1061"
     1489 type="#_x0000_t75" style='width:490pt;height:268pt;visibility:visible;
     1490 mso-wrap-style:square'>
     1491 <v:imagedata src="FindProfParamCW_files/image065.png" o:title=""/>
     1492</v:shape><![endif]--><![if !vml]><img border=0 width=492 height=270
     1493src="FindProfParamCW_files/image066.png" v:shapes="Picture_x0020_37"><![endif]></span><span
     1494style='font-size:14.0pt'><o:p></o:p></span></p>
     1495
     1496<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1497
     1498<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.5:
     1499Refine Histogram Parameters<o:p></o:p></span></h3>
     1500
     1501<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1502
     1503<p class=MsoNormal><span style='font-size:14.0pt'>We will first change a few
     1504histogram parameters. For data tree item <b style='mso-bidi-font-weight:normal'>Limits
     1505change <span class=SpellE>Tmin</span> to 20</b> degrees, as was done before in
     1506step 3. <o:p></o:p></span></p>
     1507
     1508<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1509mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_32" o:spid="_x0000_i1060"
     1510 type="#_x0000_t75" style='width:311pt;height:95pt;visibility:visible;
     1511 mso-wrap-style:square'>
     1512 <v:imagedata src="FindProfParamCW_files/image067.png" o:title=""/>
     1513</v:shape><![endif]--><![if !vml]><img border=0 width=313 height=97
     1514src="FindProfParamCW_files/image068.png" v:shapes="Picture_x0020_32"><![endif]></span><span
     1515style='font-size:14.0pt'><o:p></o:p></span></p>
     1516
     1517<p class=MsoNormal><span style='font-size:14.0pt'>For data tree item <b
     1518style='mso-bidi-font-weight:normal'>Background change </b>the Number of <span
     1519class=SpellE><b style='mso-bidi-font-weight:normal'>coeff</b></span>. <span
     1520class=GramE><b style='mso-bidi-font-weight:normal'>to</b></span><b
     1521style='mso-bidi-font-weight:normal'> 6</b>, as was done before in step 8. <o:p></o:p></span></p>
     1522
     1523<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1524mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_33" o:spid="_x0000_i1059"
     1525 type="#_x0000_t75" style='width:406pt;height:109pt;visibility:visible;
     1526 mso-wrap-style:square'>
     1527 <v:imagedata src="FindProfParamCW_files/image069.png" o:title=""/>
     1528</v:shape><![endif]--><![if !vml]><img border=0 width=408 height=111
     1529src="FindProfParamCW_files/image070.png" v:shapes="Picture_x0020_33"><![endif]></span><span
     1530style='font-size:14.0pt'><o:p></o:p></span></p>
     1531
     1532<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1533
     1534<p class=MsoNormal><span style='font-size:14.0pt'>Note that the refinement flag
     1535is on by default. We will <u>not refine</u> any of the Instrument parameters
     1536but we will refine the <b style='mso-bidi-font-weight:normal'>histogram scale
     1537factor (only)</b> on the <b style='mso-bidi-font-weight:normal'>Sample Parameters</b>.<o:p></o:p></span></p>
     1538
     1539<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1540mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_34" o:spid="_x0000_i1058"
     1541 type="#_x0000_t75" style='width:391pt;height:177pt;visibility:visible;
     1542 mso-wrap-style:square'>
     1543 <v:imagedata src="FindProfParamCW_files/image071.png" o:title=""/>
     1544</v:shape><![endif]--><![if !vml]><img border=0 width=393 height=179
     1545src="FindProfParamCW_files/image072.png" v:shapes="Picture_x0020_34"><![endif]></span><span
     1546style='font-size:14.0pt'><o:p></o:p></span></p>
     1547
     1548<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1549
     1550<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1551normal'>Calculate/Refine</b> menu item to start refinement.<span
     1552style="mso-spacerun:yes">&nbsp; </span>The program will prompt requesting a
     1553name for the <span class=GramE>newly-created</span> .<span class=SpellE>gpx</span>
     1554file. <o:p></o:p></span></p>
     1555
     1556<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1557
     1558<p class=MsoNormal><span style='font-size:14.0pt'>The fit is not very good. <b
     1559style='mso-bidi-font-weight:normal'>Clicking</b> on the histogramÕs (<b
     1560style='mso-bidi-font-weight:normal'>PWDR</b>) data tree item and zooming in
     1561shows that the <span class=GramE>tick are</span> not well aligned with the
     1562peaks. This is due to sample displacement. <o:p></o:p></span></p>
     1563
     1564<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1565mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_40" o:spid="_x0000_i1057"
     1566 type="#_x0000_t75" style='width:419pt;height:309pt;visibility:visible;
     1567 mso-wrap-style:square'>
     1568 <v:imagedata src="FindProfParamCW_files/image073.png" o:title=""/>
     1569</v:shape><![endif]--><![if !vml]><img border=0 width=421 height=311
     1570src="FindProfParamCW_files/image074.png" v:shapes="Picture_x0020_40"><![endif]></span><span
     1571style='font-size:14.0pt'><o:p></o:p></span></p>
     1572
     1573<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1574
     1575<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.6:
     1576Refine an additional Histogram Parameter<o:p></o:p></span></h3>
     1577
     1578<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1579
     1580<p class=MsoNormal><span style='font-size:14.0pt'>The position of the sample is
     1581never well determined in a Bragg-Brentano instrument, so the sample
     1582displacement should always be varied. Click on <b style='mso-bidi-font-weight:
     1583normal'>Sample Parameters </b>and turn on refinement of <b style='mso-bidi-font-weight:
     1584normal'>Sample displacement</b>.<o:p></o:p></span></p>
     1585
     1586<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1587mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_41" o:spid="_x0000_i1056"
     1588 type="#_x0000_t75" style='width:338pt;height:192pt;visibility:visible;
     1589 mso-wrap-style:square'>
     1590 <v:imagedata src="FindProfParamCW_files/image075.png" o:title=""/>
     1591</v:shape><![endif]--><![if !vml]><img border=0 width=340 height=194
     1592src="FindProfParamCW_files/image076.png" v:shapes="Picture_x0020_41"><![endif]></span><span
     1593style='font-size:14.0pt'><o:p></o:p></span></p>
     1594
     1595<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1596
     1597<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1598normal'>Calculate/Refine</b> menu item to start another refinement.<span
     1599style="mso-spacerun:yes">&nbsp; </span>Significant improvement is seen and even
     1600more if <b style='mso-bidi-font-weight:normal'>Calculate/Refine</b> is used a
     1601second time. <o:p></o:p></span></p>
     1602
     1603<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1604mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_42" o:spid="_x0000_i1055"
     1605 type="#_x0000_t75" style='width:425pt;height:315pt;visibility:visible;
     1606 mso-wrap-style:square'>
     1607 <v:imagedata src="FindProfParamCW_files/image077.png" o:title=""/>
     1608</v:shape><![endif]--><![if !vml]><img border=0 width=427 height=317
     1609src="FindProfParamCW_files/image078.png" v:shapes="Picture_x0020_42"><![endif]></span><span
     1610style='font-size:14.0pt'><o:p></o:p></span></p>
     1611
     1612<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1613mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_43" o:spid="_x0000_i1054"
     1614 type="#_x0000_t75" style='width:425pt;height:296pt;visibility:visible;
     1615 mso-wrap-style:square'>
     1616 <v:imagedata src="FindProfParamCW_files/image079.png" o:title=""/>
     1617</v:shape><![endif]--><![if !vml]><img border=0 width=427 height=298
     1618src="FindProfParamCW_files/image080.png" v:shapes="Picture_x0020_43"><![endif]></span><span
     1619style='font-size:14.0pt'><o:p></o:p></span></p>
     1620
     1621<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.6:
     1622Turn on Le Bail fitting<o:p></o:p></span></h3>
     1623
     1624<p class=MsoNormal><span style='font-size:14.0pt'>Part of the problem in the
     1625fit is that the intensities are not well fit in the model. Rather than fitting
     1626the few free structural parameters (x for B and <span class=SpellE>Uiso</span>
     1627values), we will treat the intensities are arbitrary using Le Bail fitting. <span
     1628class=GramE>This is done by clicking on the <b style='mso-bidi-font-weight:
     1629normal'>Phase tree item</b></span> and the <b style='mso-bidi-font-weight:normal'>Data
     1630tab</b> and <b style='mso-bidi-font-weight:normal'>setting</b> the <b
     1631style='mso-bidi-font-weight:normal'>do <span class=SpellE>LeBail</span></b>
     1632extraction flag.<o:p></o:p></span></p>
     1633
     1634<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1635mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_44" o:spid="_x0000_i1053"
     1636 type="#_x0000_t75" style='width:469pt;height:97pt;visibility:visible;
     1637 mso-wrap-style:square'>
     1638 <v:imagedata src="FindProfParamCW_files/image081.png" o:title=""/>
     1639</v:shape><![endif]--><![if !vml]><img border=0 width=471 height=99
     1640src="FindProfParamCW_files/image082.png" v:shapes="Picture_x0020_44"><![endif]></span><span
     1641style='font-size:14.0pt'><span style="mso-spacerun:yes">&nbsp;</span><o:p></o:p></span></p>
     1642
     1643<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1644
     1645<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1646normal'>Calculate/Refine</b> menu item to start another refinement.<span
     1647style="mso-spacerun:yes">&nbsp; </span>A warning message that ÒSteepest
     1648Descents dominatesÓ this is because a high degree of parameter correlation
     1649occurs as the reflection intensities change. The fit does not improve very much
     1650if <b style='mso-bidi-font-weight:normal'>Calculate/Refine</b> is used a second
     1651time but the warning goes away. <o:p></o:p></span></p>
     1652
     1653<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'><o:p>&nbsp;</o:p></span></h3>
     1654
     1655<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.7:
     1656Fit Lattice<o:p></o:p></span></h3>
     1657
     1658<p class=MsoNormal><span style='font-size:14.0pt'>While this should not be
     1659needed for a standard, it is clear by looking at the plots that peaks are still
     1660not quite line up. In a less dense sample it might be reasonable to refine the
     1661sample transparency, but here the only reasonable parameter is to refine the
     1662lattice. On the <b style='mso-bidi-font-weight:normal'>Phase</b>Õs <b
     1663style='mso-bidi-font-weight:normal'>General</b> tab press the <b
     1664style='mso-bidi-font-weight:normal'>Refine unit cell</b> control.<o:p></o:p></span></p>
     1665
     1666<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1667mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_46" o:spid="_x0000_i1052"
     1668 type="#_x0000_t75" style='width:354pt;height:129pt;visibility:visible;
     1669 mso-wrap-style:square'>
     1670 <v:imagedata src="FindProfParamCW_files/image083.png" o:title=""/>
     1671</v:shape><![endif]--><![if !vml]><img border=0 width=356 height=131
     1672src="FindProfParamCW_files/image084.png" v:shapes="Picture_x0020_46"><![endif]></span><span
     1673style='font-size:14.0pt'><o:p></o:p></span></p>
     1674
     1675<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1676normal'>Calculate/Refine</b> menu item to start another refinement and the
     1677positioning of the peaks improves significantly. <o:p></o:p></span></p>
     1678
     1679<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.8:
     1680Fit <span class=SpellE>MicroStrain</span><o:p></o:p></span></h3>
     1681
     1682<p class=MsoNormal><span style='font-size:14.0pt'>The remaining major problem
     1683is that we have not treated the sample broadening and LaB6 does have some <span
     1684class=SpellE>microstrain</span>. That can be refined on <span class=GramE>the <span
     1685style="mso-spacerun:yes">&nbsp;</span>s</span>. One is that can be refined with
     1686the <b style='mso-bidi-font-weight:normal'>Phase</b>Õs <b style='mso-bidi-font-weight:
     1687normal'>Data</b> tab with the <span class=SpellE>microstrain</span> control.<o:p></o:p></span></p>
     1688
     1689<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1690mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_45" o:spid="_x0000_i1051"
     1691 type="#_x0000_t75" style='width:729pt;height:104pt;visibility:visible;
     1692 mso-wrap-style:square'>
     1693 <v:imagedata src="FindProfParamCW_files/image085.png" o:title=""/>
     1694</v:shape><![endif]--><![if !vml]><img border=0 width=731 height=106
     1695src="FindProfParamCW_files/image086.png" v:shapes="Picture_x0020_45"><![endif]></span><span
     1696style='font-size:14.0pt'><o:p></o:p></span></p>
     1697
     1698<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1699
     1700<p class=MsoNormal><span style='font-size:14.0pt'>Use the <b style='mso-bidi-font-weight:
     1701normal'>Calculate/Refine</b> menu item to start another refinement. A second
     1702refinement cycle brings the <span class=SpellE>Rw</span> to circa 5.8%. The fit
     1703improves dramatically and <span class=SpellE>microstrain</span> refines to a
     1704non-physical negative value. This is because our somewhat na•ve approach above
     1705assumed no sample broadening. <o:p></o:p></span></p>
     1706
     1707<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1708
     1709<p class=MsoNormal><i style='mso-bidi-font-style:normal'><span
     1710style='font-size:14.0pt'>This shows why if determination of <span class=SpellE>microstrain</span>
     1711and/or crystallite size broadening <span class=GramE>is intended to be measured</span>
     1712quantitatively, the instrument profile is best determined by a Rietveld fit and
     1713with fixed (known) values for the <span class=SpellE>microstrain</span> and
     1714size in the standard. <o:p></o:p></span></i></p>
     1715
     1716<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.9:
     1717Additional Parameters<o:p></o:p></span></h3>
     1718
     1719<p class=MsoNormal><span style='font-size:14.0pt'>For these data, it appears
     1720the ratio of Kalpha1 and Kalpha2 is not exactly the theoretical value of 0.5.
     1721This can happen due to monochromator tuning. Allowing this to shift slightly by
     1722including brings the <span class=SpellE>Rw</span> to circa 4.9%.<o:p></o:p></span></p>
     1723
     1724<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1725mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_47" o:spid="_x0000_i1050"
     1726 type="#_x0000_t75" style='width:277pt;height:88pt;visibility:visible;
     1727 mso-wrap-style:square'>
     1728 <v:imagedata src="FindProfParamCW_files/image087.png" o:title=""/>
     1729</v:shape><![endif]--><![if !vml]><img border=0 width=279 height=90
     1730src="FindProfParamCW_files/image088.png" v:shapes="Picture_x0020_47"><![endif]></span><span
     1731style='font-size:14.0pt'><o:p></o:p></span></p>
     1732
     1733<p class=MsoNormal><span style='font-size:14.0pt'>The fit is quite good without
     1734fitting the instrumental profile terms: <o:p></o:p></span></p>
     1735
     1736<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1737mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_49" o:spid="_x0000_i1049"
     1738 type="#_x0000_t75" style='width:627pt;height:363pt;visibility:visible;
     1739 mso-wrap-style:square'>
     1740 <v:imagedata src="FindProfParamCW_files/image089.png" o:title=""/>
     1741</v:shape><![endif]--><![if !vml]><img border=0 width=629 height=365
     1742src="FindProfParamCW_files/image090.png" v:shapes="Picture_x0020_49"><![endif]></span><span
     1743style='font-size:14.0pt'><o:p></o:p></span></p>
     1744
     1745<p class=MsoNormal><span style='font-size:14.0pt'><o:p>&nbsp;</o:p></span></p>
     1746
     1747<h3><span style='font-size:14.0pt;mso-bidi-font-family:"Times New Roman"'>Step 2.10:
     1748Profile Term Quality Check<o:p></o:p></span></h3>
     1749
     1750<p class=MsoNormal><span style='font-size:14.0pt'>The quality of the profile
     1751parameters we previously fit can be demonstrated by turning off refinement of the
     1752<span class=SpellE>microstrain</span> term and refining the U, V, W and X &amp;
     1753Y terms. This produces a small improvement in the fit (expected as one fitting
     1754parameter as been replaced by 5), but the changes are very small, as noted by
     1755the Instrument Parameter terms plot:<o:p></o:p></span></p>
     1756
     1757<p class=MsoNormal><span style='font-size:14.0pt;mso-fareast-language:EN-US;
     1758mso-no-proof:yes'><!--[if gte vml 1]><v:shape id="Picture_x0020_48" o:spid="_x0000_i1048"
     1759 type="#_x0000_t75" style='width:531pt;height:395pt;visibility:visible;
     1760 mso-wrap-style:square'>
     1761 <v:imagedata src="FindProfParamCW_files/image091.png" o:title=""/>
     1762</v:shape><![endif]--><![if !vml]><img border=0 width=533 height=397
     1763src="FindProfParamCW_files/image092.png" v:shapes="Picture_x0020_48"><![endif]></span><span
     1764style='font-size:14.0pt'><o:p></o:p></span></p>
    12221765
    12231766</div>
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