1 | <html> |
---|
2 | |
---|
3 | <head> |
---|
4 | <meta http-equiv=Content-Type content="text/html; charset=windows-1252"> |
---|
5 | <meta name=Generator content="Microsoft Word 15 (filtered)"> |
---|
6 | <style> |
---|
7 | <!-- |
---|
8 | /* Font Definitions */ |
---|
9 | @font-face |
---|
10 | {font-family:"Cambria Math"; |
---|
11 | panose-1:2 4 5 3 5 4 6 3 2 4;} |
---|
12 | @font-face |
---|
13 | {font-family:Calibri; |
---|
14 | panose-1:2 15 5 2 2 2 4 3 2 4;} |
---|
15 | @font-face |
---|
16 | {font-family:Tahoma; |
---|
17 | panose-1:2 11 6 4 3 5 4 4 2 4;} |
---|
18 | /* Style Definitions */ |
---|
19 | p.MsoNormal, li.MsoNormal, div.MsoNormal |
---|
20 | {margin:0in; |
---|
21 | margin-bottom:.0001pt; |
---|
22 | font-size:12.0pt; |
---|
23 | font-family:"Times New Roman",serif;} |
---|
24 | h1 |
---|
25 | {mso-style-link:"Heading 1 Char"; |
---|
26 | margin-right:0in; |
---|
27 | margin-left:0in; |
---|
28 | font-size:24.0pt; |
---|
29 | font-family:"Times New Roman",serif; |
---|
30 | font-weight:bold;} |
---|
31 | h2 |
---|
32 | {mso-style-link:"Heading 2 Char"; |
---|
33 | margin-right:0in; |
---|
34 | margin-left:0in; |
---|
35 | font-size:18.0pt; |
---|
36 | font-family:"Times New Roman",serif; |
---|
37 | font-weight:bold;} |
---|
38 | h3 |
---|
39 | {mso-style-link:"Heading 3 Char"; |
---|
40 | margin-right:0in; |
---|
41 | margin-left:0in; |
---|
42 | font-size:13.5pt; |
---|
43 | font-family:"Times New Roman",serif; |
---|
44 | font-weight:bold;} |
---|
45 | h4 |
---|
46 | {mso-style-link:"Heading 4 Char"; |
---|
47 | margin-top:10.0pt; |
---|
48 | margin-right:0in; |
---|
49 | margin-bottom:0in; |
---|
50 | margin-left:0in; |
---|
51 | margin-bottom:.0001pt; |
---|
52 | page-break-after:avoid; |
---|
53 | font-size:13.0pt; |
---|
54 | font-family:"Cambria",serif; |
---|
55 | color:#4F81BD; |
---|
56 | font-weight:bold; |
---|
57 | font-style:italic;} |
---|
58 | h5 |
---|
59 | {mso-style-link:"Heading 5 Char"; |
---|
60 | margin-right:0in; |
---|
61 | margin-left:0in; |
---|
62 | font-size:12.0pt; |
---|
63 | font-family:"Times New Roman",serif; |
---|
64 | color:#4F4FFF; |
---|
65 | font-weight:bold;} |
---|
66 | a:link, span.MsoHyperlink |
---|
67 | {color:blue; |
---|
68 | text-decoration:underline;} |
---|
69 | a:visited, span.MsoHyperlinkFollowed |
---|
70 | {color:purple; |
---|
71 | text-decoration:underline;} |
---|
72 | p.MsoDocumentMap, li.MsoDocumentMap, div.MsoDocumentMap |
---|
73 | {mso-style-link:"Document Map Char"; |
---|
74 | margin:0in; |
---|
75 | margin-bottom:.0001pt; |
---|
76 | font-size:8.0pt; |
---|
77 | font-family:"Tahoma",sans-serif;} |
---|
78 | p |
---|
79 | {margin-right:0in; |
---|
80 | margin-left:0in; |
---|
81 | font-size:12.0pt; |
---|
82 | font-family:"Times New Roman",serif;} |
---|
83 | pre |
---|
84 | {mso-style-link:"HTML Preformatted Char"; |
---|
85 | margin:0in; |
---|
86 | margin-bottom:.0001pt; |
---|
87 | font-size:10.0pt; |
---|
88 | font-family:"Courier New";} |
---|
89 | p.MsoAcetate, li.MsoAcetate, div.MsoAcetate |
---|
90 | {mso-style-link:"Balloon Text Char"; |
---|
91 | margin:0in; |
---|
92 | margin-bottom:.0001pt; |
---|
93 | font-size:8.0pt; |
---|
94 | font-family:"Tahoma",sans-serif;} |
---|
95 | span.MsoPlaceholderText |
---|
96 | {color:gray;} |
---|
97 | p.MsoNoSpacing, li.MsoNoSpacing, div.MsoNoSpacing |
---|
98 | {margin:0in; |
---|
99 | margin-bottom:.0001pt; |
---|
100 | font-size:12.0pt; |
---|
101 | font-family:"Times New Roman",serif;} |
---|
102 | p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph |
---|
103 | {margin-top:0in; |
---|
104 | margin-right:0in; |
---|
105 | margin-bottom:0in; |
---|
106 | margin-left:.5in; |
---|
107 | margin-bottom:.0001pt; |
---|
108 | font-size:12.0pt; |
---|
109 | font-family:"Times New Roman",serif;} |
---|
110 | p.MsoListParagraphCxSpFirst, li.MsoListParagraphCxSpFirst, div.MsoListParagraphCxSpFirst |
---|
111 | {margin-top:0in; |
---|
112 | margin-right:0in; |
---|
113 | margin-bottom:0in; |
---|
114 | margin-left:.5in; |
---|
115 | margin-bottom:.0001pt; |
---|
116 | font-size:12.0pt; |
---|
117 | font-family:"Times New Roman",serif;} |
---|
118 | p.MsoListParagraphCxSpMiddle, li.MsoListParagraphCxSpMiddle, div.MsoListParagraphCxSpMiddle |
---|
119 | {margin-top:0in; |
---|
120 | margin-right:0in; |
---|
121 | margin-bottom:0in; |
---|
122 | margin-left:.5in; |
---|
123 | margin-bottom:.0001pt; |
---|
124 | font-size:12.0pt; |
---|
125 | font-family:"Times New Roman",serif;} |
---|
126 | p.MsoListParagraphCxSpLast, li.MsoListParagraphCxSpLast, div.MsoListParagraphCxSpLast |
---|
127 | {margin-top:0in; |
---|
128 | margin-right:0in; |
---|
129 | margin-bottom:0in; |
---|
130 | margin-left:.5in; |
---|
131 | margin-bottom:.0001pt; |
---|
132 | font-size:12.0pt; |
---|
133 | font-family:"Times New Roman",serif;} |
---|
134 | span.MsoIntenseReference |
---|
135 | {font-variant:small-caps; |
---|
136 | color:#C0504D; |
---|
137 | letter-spacing:.25pt; |
---|
138 | font-weight:bold; |
---|
139 | text-decoration:underline;} |
---|
140 | span.Heading1Char |
---|
141 | {mso-style-name:"Heading 1 Char"; |
---|
142 | mso-style-link:"Heading 1"; |
---|
143 | font-family:"Times New Roman",serif; |
---|
144 | font-weight:bold;} |
---|
145 | span.Heading2Char |
---|
146 | {mso-style-name:"Heading 2 Char"; |
---|
147 | mso-style-link:"Heading 2"; |
---|
148 | font-family:"Times New Roman",serif; |
---|
149 | font-weight:bold;} |
---|
150 | span.Heading3Char |
---|
151 | {mso-style-name:"Heading 3 Char"; |
---|
152 | mso-style-link:"Heading 3"; |
---|
153 | font-family:"Times New Roman",serif; |
---|
154 | font-weight:bold;} |
---|
155 | span.Heading4Char |
---|
156 | {mso-style-name:"Heading 4 Char"; |
---|
157 | mso-style-link:"Heading 4"; |
---|
158 | font-family:"Cambria",serif; |
---|
159 | color:#4F81BD; |
---|
160 | font-weight:bold; |
---|
161 | font-style:italic;} |
---|
162 | span.Heading5Char |
---|
163 | {mso-style-name:"Heading 5 Char"; |
---|
164 | mso-style-link:"Heading 5"; |
---|
165 | font-family:"Times New Roman",serif; |
---|
166 | color:#4F4FFF; |
---|
167 | font-weight:bold;} |
---|
168 | span.HTMLPreformattedChar |
---|
169 | {mso-style-name:"HTML Preformatted Char"; |
---|
170 | mso-style-link:"HTML Preformatted"; |
---|
171 | font-family:"Courier New";} |
---|
172 | p.msonormal0, li.msonormal0, div.msonormal0 |
---|
173 | {mso-style-name:msonormal; |
---|
174 | margin-right:0in; |
---|
175 | margin-left:0in; |
---|
176 | font-size:12.0pt; |
---|
177 | font-family:"Times New Roman",serif;} |
---|
178 | span.DocumentMapChar |
---|
179 | {mso-style-name:"Document Map Char"; |
---|
180 | mso-style-link:"Document Map"; |
---|
181 | font-family:"Tahoma",sans-serif;} |
---|
182 | span.BalloonTextChar |
---|
183 | {mso-style-name:"Balloon Text Char"; |
---|
184 | mso-style-link:"Balloon Text"; |
---|
185 | font-family:"Tahoma",sans-serif;} |
---|
186 | span.GSAS-IItextChar |
---|
187 | {mso-style-name:"GSAS-II text Char"; |
---|
188 | mso-style-link:"GSAS-II text"; |
---|
189 | font-family:"Times New Roman",serif; |
---|
190 | font-weight:bold;} |
---|
191 | p.GSAS-IItext, li.GSAS-IItext, div.GSAS-IItext |
---|
192 | {mso-style-name:"GSAS-II text"; |
---|
193 | mso-style-link:"GSAS-II text Char"; |
---|
194 | margin:0in; |
---|
195 | margin-bottom:.0001pt; |
---|
196 | font-size:12.0pt; |
---|
197 | font-family:"Calibri",sans-serif; |
---|
198 | font-weight:bold;} |
---|
199 | .MsoChpDefault |
---|
200 | {font-size:10.0pt; |
---|
201 | font-family:"Calibri",sans-serif;} |
---|
202 | @page WordSection1 |
---|
203 | {size:8.5in 11.0in; |
---|
204 | margin:1.0in 1.0in 1.0in 1.0in;} |
---|
205 | div.WordSection1 |
---|
206 | {page:WordSection1;} |
---|
207 | --> |
---|
208 | </style> |
---|
209 | |
---|
210 | </head> |
---|
211 | |
---|
212 | <body lang=EN-US link=blue vlink=purple> |
---|
213 | |
---|
214 | <div class=WordSection1> |
---|
215 | |
---|
216 | <h1>Stacking Fault Simulations III</h1> |
---|
217 | |
---|
218 | <p class=MsoNormal>Here we continue the simulation of kaolinites started in |
---|
219 | Stacking Faults-II. If you have not done this exercise and finished by saving |
---|
220 | the project file (kaolinite.gpx) please do that first as this exercise uses the |
---|
221 | results of that exercise. The data we are trying to simulated is from a less |
---|
222 | well ordered kaolinite from Washington County, Georgia (Clay Minerals Society |
---|
223 | Standard KGa-1b) collected with CuKa radiation on a Bruker instrument and thus |
---|
224 | in the Bruker RAW file format. The KGa-1b sample contains a small amount of |
---|
225 | anatase (TiO<sub>2</sub>).</p> |
---|
226 | |
---|
227 | <p class=MsoNormal>If you have not done so already, start GSAS-II and open your |
---|
228 | kaolinite.gpx file.</p> |
---|
229 | |
---|
230 | <h2>Part 1. Create a new phase</h2> |
---|
231 | |
---|
232 | <p class=MsoNormal>We will need a new faulted phase for the simulation of the |
---|
233 | Georgia (Ga-1b) kaolinite pattern. Do <b><span style='font-family:"Calibri",sans-serif'>Data/Add |
---|
234 | new phase</span></b> and give it a name (I chose <b><span style='font-family: |
---|
235 | "Calibri",sans-serif'>Georgia</span></b>); the General tab will be displayed. |
---|
236 | Change the <b><span style='font-family:"Calibri",sans-serif'>Phase type</span></b> |
---|
237 | to <b><span style='font-family:"Calibri",sans-serif'>faulted</span></b>; the |
---|
238 | page will be redrawn and a new tab (Layers) will appear. Select it.</p> |
---|
239 | |
---|
240 | <p class=MsoNormal><img width=624 height=370 id="Picture 1" |
---|
241 | src="Stacking%20Faults-III_files/image002.gif"> We need to enter the kaolinite |
---|
242 | abc* lattice parameters; these can be obtained from the kaolinite.gpx project file. |
---|
243 | Do <b><span style='font-family:"Calibri",sans-serif'>Operations/Copy phase cell</span></b>; |
---|
244 | a file selection dialog will appear showing <b><span style='font-family:"Calibri",sans-serif'>kaolinite.gpx</span></b>. |
---|
245 | Select it and then select <b><span style='font-family:"Calibri",sans-serif'>kaolinite |
---|
246 | abc*</span></b> from the next popup window; the Layers tab will be redrawn with |
---|
247 | the new lattice parameters.</p> |
---|
248 | |
---|
249 | <p class=MsoNormal><img width=624 height=365 id="Picture 2" |
---|
250 | src="Stacking%20Faults-III_files/image004.gif"></p> |
---|
251 | |
---|
252 | <p class=MsoNormal>Well add the layers in a moment.</p> |
---|
253 | |
---|
254 | <h2>Part 2. Import powder data to simulate.</h2> |
---|
255 | |
---|
256 | <p class=MsoNormal>The powder data from the Ga-1b (kaolinite from Washington |
---|
257 | Cty., Georgia) is what we are going to simulate; do <b><span style='font-family: |
---|
258 | "Calibri",sans-serif'>Import/Powder Data/from Bruker RAW file</span></b>. |
---|
259 | Select <b><span style='font-family:"Calibri",sans-serif'>KGA1-CONT.RAW</span></b>; |
---|
260 | answer <b><span style='font-family:"Calibri",sans-serif'>Yes</span></b> for |
---|
261 | question about the file. We will use the internal default instrument |
---|
262 | parameters; press <b><span style='font-family:"Calibri",sans-serif'>Cancel</span></b> |
---|
263 | on the file selection dialog and select <b><span style='font-family:"Calibri",sans-serif'>Defaults |
---|
264 | for CuKa lab data</span></b> from the next popup. The next popup asks about the |
---|
265 | phases to be included.</p> |
---|
266 | |
---|
267 | <p class=MsoNormal><img width=320 height=299 id="Picture 3" |
---|
268 | src="Stacking%20Faults-III_files/image006.gif"></p> |
---|
269 | |
---|
270 | <p class=MsoNormal>Select <b><span style='font-family:"Calibri",sans-serif'>Georgia</span></b> |
---|
271 | which is the faulted phase created in Step 1. The pattern will be displayed.</p> |
---|
272 | |
---|
273 | <p class=MsoNormal><img width=624 height=535 id="Picture 4" |
---|
274 | src="Stacking%20Faults-III_files/image008.gif"></p> |
---|
275 | |
---|
276 | <p class=MsoNormal>It covers 2-70° 2Θ and shows some of the obvious |
---|
277 | characteristics of stacking faults, especially the sharp rise/sloping |
---|
278 | background feature at 20-30° 2Θ. We want to limit the range for the |
---|
279 | simulation to be <b><span style='font-family:"Calibri",sans-serif'>10-52</span></b>° |
---|
280 | 2Θ (do this in <b><span style='font-family:"Calibri",sans-serif'>Limits</span></b> |
---|
281 | under <b><span style='font-family:"Calibri",sans-serif'>PWDR KGA1-CONT.RAW Scan |
---|
282 | 1</span></b>), set the first background coefficient to something reasonable (in |
---|
283 | <b><span style='font-family:"Calibri",sans-serif'>Background</span></b> & |
---|
284 | the flat portion < 20° 2Θ = ~<b><span style='font-family:"Calibri",sans-serif'>80</span></b>). |
---|
285 | In <b><span style='font-family:"Calibri",sans-serif'>Instrument Parameters</span></b> |
---|
286 | change <b><span style='font-family:"Calibri",sans-serif'>W</span></b> to <b><span |
---|
287 | style='font-family:"Calibri",sans-serif'>40</span></b> and in <b><span |
---|
288 | style='font-family:"Calibri",sans-serif'>Sample Parameters</span></b> set the <b><span |
---|
289 | style='font-family:"Calibri",sans-serif'>Histogram scale factor</span></b> to <b><span |
---|
290 | style='font-family:"Calibri",sans-serif'>40</span></b>. Also change <b><span |
---|
291 | style='font-family:"Calibri",sans-serif'>Diffractometer type</span></b> to <b><span |
---|
292 | style='font-family:"Calibri",sans-serif'>Bragg-Brentano</span></b>. The powder |
---|
293 | pattern will show the new limits.</p> |
---|
294 | |
---|
295 | <p class=MsoNormal><img width=624 height=535 id="Picture 5" |
---|
296 | src="Stacking%20Faults-III_files/image010.gif"></p> |
---|
297 | |
---|
298 | <p class=MsoNormal>Finally select the <b><span style='font-family:"Calibri",sans-serif'>Georgia</span></b> |
---|
299 | phase and the <b><span style='font-family:"Calibri",sans-serif'>Data</span></b> |
---|
300 | tab; it will be empty.</p> |
---|
301 | |
---|
302 | <p class=MsoNormal><img width=440 height=192 id="Picture 10" |
---|
303 | src="Stacking%20Faults-III_files/image018.gif"></p> |
---|
304 | |
---|
305 | <p class=MsoNormal>Do <b><span style='font-family:"Calibri",sans-serif'>Edit/Add |
---|
306 | powder histograms</span></b>; a popup will show the available PWDR data sets. Select |
---|
307 | just <b><span style='font-family:"Calibri",sans-serif'>PWDR KGA1-CONT.RAW Scan |
---|
308 | 1</span></b> and press <b><span style='font-family:"Calibri",sans-serif'>OK</span></b>. |
---|
309 | The Data tab will be redrawn; currently none of this information is of use in |
---|
310 | stacking fault simulations.</p> |
---|
311 | |
---|
312 | <h2>Step 3. Setup layer model for simulation.</h2> |
---|
313 | |
---|
314 | <p class=MsoNormal>We now need to fill the layer data with atoms and develop a |
---|
315 | stacking fault model for the simulation. Select the <b><span style='font-family: |
---|
316 | "Calibri",sans-serif'>Georgia</span></b> phase and the <b><span |
---|
317 | style='font-family:"Calibri",sans-serif'>Layers</span></b> tab.</p> |
---|
318 | |
---|
319 | <p class=MsoNormal><img width=624 height=365 id="Picture 6" |
---|
320 | src="Stacking%20Faults-III_files/image019.gif"></p> |
---|
321 | |
---|
322 | <p class=MsoNormal>To begin we need a kaolinite layer; you can use <b><span |
---|
323 | style='font-family:"Calibri",sans-serif'>Import new layer</span></b> as before. |
---|
324 | Select <b><span style='font-family:"Calibri",sans-serif'>kaolinite.gpx</span></b> |
---|
325 | and pick <b><span style='font-family:"Calibri",sans-serif'>kaolinite abc*</span></b> |
---|
326 | from the list of phases; the Layers tab will be redrawn showing the atom list |
---|
327 | for the layer.</p> |
---|
328 | |
---|
329 | <p class=MsoNormal><img width=624 height=377 id="Picture 7" |
---|
330 | src="Stacking%20Faults-III_files/image020.gif"></p> |
---|
331 | |
---|
332 | <p class=MsoNormal>Change the <b><span style='font-family:"Calibri",sans-serif'>Layer |
---|
333 | name</span></b> to <b><span style='font-family:"Calibri",sans-serif'>kaolinite |
---|
334 | A</span></b> (the Layers tab will be redrawn).</p> |
---|
335 | |
---|
336 | <p class=MsoNormal>To make a defect structure we need a second layer which will |
---|
337 | be the same as the first one; select <b><span style='font-family:"Calibri",sans-serif'>Add |
---|
338 | new layer</span></b>. The Layers tab will be redrawn again. Scroll down (might |
---|
339 | need a slight tug on an edge to get the scroll to show) to find the new layer.</p> |
---|
340 | |
---|
341 | <p class=MsoNormal> <img width=624 height=377 id="Picture 9" |
---|
342 | src="Stacking%20Faults-III_files/image021.gif"></p> |
---|
343 | |
---|
344 | <p class=MsoNormal>Change the <b><span style='font-family:"Calibri",sans-serif'>Layer |
---|
345 | name</span></b> to something other than Unk; I used <b><span |
---|
346 | style='font-family:"Calibri",sans-serif'>kaolinite B</span></b> (the tab is |
---|
347 | redrawn). Then change the <b><span style='font-family:"Calibri",sans-serif'>Same |
---|
348 | as</span></b> to <b><span style='font-family:"Calibri",sans-serif'>kaolinite A</span></b>; |
---|
349 | that gives it the same set of atom parameters. Finally change all <b><span |
---|
350 | style='font-family:"Calibri",sans-serif'>Dx=-.368, Dy=-.0246 </span></b>and<b><span |
---|
351 | style='font-family:"Calibri",sans-serif'> Dz=1.0</span></b>; this will be the |
---|
352 | same as the triclinic Kaokuk stacking arrangement. Set the kaolinite A-A and |
---|
353 | B-B probabilities to 1.0 and the cross terms to 0.0 to reproduce the ordered |
---|
354 | stacking. </p> |
---|
355 | |
---|
356 | <h2>Step 4. Simulations of Georgia kaolinite</h2> |
---|
357 | |
---|
358 | <p class=MsoNormal>To do the simulation do <b><span style='font-family:"Calibri",sans-serif'>Operations/Simulate |
---|
359 | pattern</span></b> and <b><span style='font-family:"Calibri",sans-serif'>Ok</span></b> |
---|
360 | for the next two popups. </p> |
---|
361 | |
---|
362 | <p class=MsoNormal>Artioli, M<img width=624 height=535 id="Picture 11" |
---|
363 | src="Stacking%20Faults-III_files/image022.gif"></p> |
---|
364 | |
---|
365 | <p class=MsoNormal>The result should be nearly identical to the one we obtained |
---|
366 | for Keokuk kaolinite and it does not represent the data very well especially in |
---|
367 | the 20-30° 2Θ region. The intent of having the 2<sup>nd</sup> kaolinite |
---|
368 | layer is to displace it relative to the first one as a stacking fault. The |
---|
369 | literature has many such models suggested (e.g. see G. Artioli, et al. Clays |
---|
370 | & Clay Min., 43, 438-445, 1995); a simple one is to displace the 2<sup>nd</sup> |
---|
371 | layer by b/3 which places the SiO4 layer in the same alignment with the |
---|
372 | previous AlO6 layer but with effectively a different orientation than for a pair |
---|
373 | of Keokuk layers. Compare the Keokuk stacking (I pressed the <b><span |
---|
374 | style='font-family:"Calibri",sans-serif'>L</span></b> & <b><span |
---|
375 | style='font-family:"Calibri",sans-serif'>F</span></b> keys get labels & |
---|
376 | fade the 2<sup>nd</sup> layer).</p> |
---|
377 | |
---|
378 | <p class=MsoNormal><img width=477 height=356 id="Picture 12" |
---|
379 | src="Stacking%20Faults-III_files/image023.jpg"></p> |
---|
380 | |
---|
381 | <p class=MsoNormal>With the kaolinite A-B <b><span style='font-family:"Calibri",sans-serif'>Dy</span></b>=1/3-0.0246=<b><span |
---|
382 | style='font-family:"Calibri",sans-serif'>0.3087</span></b>.</p> |
---|
383 | |
---|
384 | <p class=MsoNormal><img width=478 height=358 id="Picture 13" |
---|
385 | src="Stacking%20Faults-III_files/image024.jpg"></p> |
---|
386 | |
---|
387 | <p class=MsoNormal>If you carefully compare these two drawings, you can see |
---|
388 | that the orientation of the 2<sup>nd</sup> (faded) layer with the 1<sup>st</sup> |
---|
389 | layer is the virtually same for both but in different directions. You should check |
---|
390 | that the kaolinite B-A and B-B stacking shows the same relationship (change |
---|
391 | kaolinite B-A <b><span style='font-family:"Calibri",sans-serif'>Dy=0.3087</span></b>). |
---|
392 | Next, change all the probabilities to <b><span style='font-family:"Calibri",sans-serif'>0.5</span></b> |
---|
393 | and rerun the simulation.</p> |
---|
394 | |
---|
395 | <p class=MsoNormal>O low; evidently this data <img width=624 height=535 |
---|
396 | id="Picture 14" src="Stacking%20Faults-III_files/image025.gif"></p> |
---|
397 | |
---|
398 | <p class=MsoNormal>The 20-30° 2Θ region is not well reproduced; the |
---|
399 | features are in the wrong place and are too broad. There is probably too much |
---|
400 | disorder in this model. The <b><span style='font-family:"Calibri",sans-serif'>Histogram |
---|
401 | scale factor</span></b> is also too low; evidently this data set was collected |
---|
402 | with at least twice the step time as the Keokuk one. Go change it to <b><span |
---|
403 | style='font-family:"Calibri",sans-serif'>80</span></b> and rerun the |
---|
404 | simulation. Ive expanded the 20-30° 2Θ region to see the fit.</p> |
---|
405 | |
---|
406 | <p class=MsoNormal><img width=624 height=535 id="Picture 15" |
---|
407 | src="Stacking%20Faults-III_files/image026.gif"></p> |
---|
408 | |
---|
409 | <p class=MsoNormal>You can use trial & error adjusting the probabilities to |
---|
410 | find a better model. One with kaolinite A-A and kaolinite B-B probability of <b><span |
---|
411 | style='font-family:"Calibri",sans-serif'>0.8</span></b> and the cross terms at <b><span |
---|
412 | style='font-family:"Calibri",sans-serif'>0.2</span></b> gives a reasonable |
---|
413 | simulation.</p> |
---|
414 | |
---|
415 | <p class=MsoNormal><img width=624 height=535 id="Picture 16" |
---|
416 | src="Stacking%20Faults-III_files/image027.gif"></p> |
---|
417 | |
---|
418 | <p class=MsoNormal>The background feature in the 20-30° 2Θ is reasonably |
---|
419 | well represented with the peaks correctly positioned and with the right |
---|
420 | intensity. One can create more elaborate models using additional stacking |
---|
421 | layers; see the paper by G. Artioli noted above for some choices. This |
---|
422 | completes the stacking fault simulation exercises; save your project file.</p> |
---|
423 | |
---|
424 | </div> |
---|
425 | |
---|
426 | </body> |
---|
427 | |
---|
428 | </html> |
---|