Re: Li2SnO3
Who know the atom fractional coordinates of Li2SnO3? there is some confusion about the correct coordinates in the old (1954 Lang, Z. Anorg. Allg. Chem.) literature. the correct values are: TITL Lithium stannate TITL Li2 Sn O3 Die Kristallstruktur von Li2SnO3 Kreuzburg G Stewner F Hoppe R TITL Z. Anorg. Allg. Chem. CELL 1.54178 5.29500 9.18400 10.03200 90.000 100.130 90.000 C 2/C Li1 0.23900 0.07800 -0.00100 1.0 0.01 Li2 0.25000 0.25000 0.5 0.5 0.01 Li3 0.0 0.08300 0.25000 0.5 0.01 Sn1 0.0 0.41650 0.25000 0.5 0.01 Sn2 0.0 0.75080 0.25000 0.5 0.01 O1 0.13370 0.25970 0.13330 1.0 0.01 O2 0.11020 0.58440 0.13420 1.0 0.01 O3 0.13460 0.90920 0.13290 1.0 0.01 caroline.
Re: Li2SnO3
TITL Li2 Sn O3 Die Kristallstruktur von Li2SnO3 Kreuzburg G Stewner F Hoppe Actually a more recent paper (using neutron Rietveld refinement :-) is: Hodeau,JL. Marezio,M. Santoro,A. Roth,RS. (1982) J.Solid State Chem 45 170-179 Neutron Profile Refinement of the Structures of Li2 Sn O3 and Li2 Zr O3 Alan. Dr Alan W. Hewat, Diffraction Group Leader. Institut Laue-Langevin, BP 156X Grenoble FRANCE fax (33)4.76.20.76.48 tel (33) 4.76.20.72.13 (or .26) [EMAIL PROTECTED] http://www.ill.fr/dif/AlanHewat.htm
Quantification of soil clay minerals
Dear Marcelo, There is no simple answer to your question about using the Rietveld method to quantify clay minerals in soils, or clay minerals by the Rietveld method in any sample for that matter. If your clay mineral assemblage is simple, and the clay minerals well crystallised with no 2D diffraction effects you may be able to get by. If on the other hand, the clay mineral assemblage is complex and the clay minerals poorly ordered you will face many more problems. Here at Macaulay Institite we tend to prefer the classic RIR method where clay minerals are concerned. Although the RIR method has its own drawbacks and fullpattern approaches seem much more elegant; when it comes to clay minerals, soil clay minerals especially, it can be considerably easier to measure a single peak that can be unequivocally assigned to one clay mineral or another than to try and model the contribution of a combination of poorly ordered clay minerals to a full pattern, invariably including other minerals in addtion to clays. At then end of the day the accuracy of which ever method you use will also depend on how much you know about the clays in your sample. Which ever method you decide upon I would always advise on taking the effort to add an internal standard. Even if you use the Rietveld method the addittion of a standard is about the only way to have some confidence that the quantification of an unknown is reasonable. An age old problem you will also face with clay minerals is preferred orientation, At the Macaulay Institute we spray dry all our samples to be sure that we eliminate preferred orientation before we start. http://www.mluri.sari.ac.uk/newcommercialservices/spray/index.html This makes single/several peak RIR methods much more precise and accurate it also means you have at least one less varaible to refine if you use the Rietveld method. If you want some literature on this subject the chapters by Bish and by Hughes et al on XRPD in the following reference are a good starting point. Amonette, J.E. Zelazny, L.W. (1994) Quantitative methods in soil mineralogy. Soil Science Society of America Inc. Madison, Wisconsin, USA. Sincerely, Steve -- Stephen Hillier Macaulay Land Use Research Inst. Craigiebuckler ABERDEEN AB15 8QH Tel. +44 (0)1224 318611 Fax. +44 (0)1224 311556
Re: Li2SnO3
Dear Dr. Liu: I have handy two reprints about the crystal structure of Li2SnO3. Data are as follows: G.Kreuzburg, F. Stewner und R. Hoppe, Z.Anorg.Allg.Chem., v. 379, pp.242-254,(1970) S.G. C2/c; a=5.295, b=9.184, c=10.032, beta=100.13 deg., Z=8 Single Crystal XRD data Atomposition xyz Biso Li(1)8(f)0.239 0.078 -0.001 1.1 Li(2)4(d) 1/4 1/4 1/2 1.5 Li(3)* 4(e) 0 0.083* 1/4 3.8 Sn(1) 4(e) 0 0.41651/4 0.18 Sn(2) 4(e) 0 0.75081/4 0.15 O(1) 8(f)0.1337 0.2597 0.1333 0.49 O(2) 8(f)0.1102 0.5844 0.1342 0.68 O(3) 8(f)0.1346 0.9092 0.1329 0.48 * calculated (not refined) value END NEXT J.L.Hodeau, M.Marezio, A.Santoro and R.S.Roth, J.Solid State Chem., v.45, pp.170-179 (1982) S.G. C2/c;a=5.2889,b=9.1872,c=10.026, beta=100.348 deg., Z=8 Neutron Powder Diffraction Data x y z Biso Sn(1)4(e)0 0.418 1/4 0.2 Sn(2)4(e)0 0.7501 1/4 0.2 O(1) 8(f) 0.1387 0.2610 0.1339 0.48 O(2) 8(f) 0.1118 0.5853 0.1340 0.19 O(3) 8(f) 0.1343 0.9078 0.1322 0.15 Li(1) 8(f) 0.231 0.073 -0.0006 1.5 Li(2) 4(d)1/41/41/2 1.5 Li(3) 4(e) 0 0.083 1/4 1.5 END K.Petrov E-mail:[EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [EMAIL PROTECTED] To: [EMAIL PROTECTED] [EMAIL PROTECTED] Date: ÞÅÔ×ß×ÔßË, íÁÊ 31, 2001 03:21 Subject: Li2SnO3 Hi,everyone Who know the atom fractional coordinates of Li2SnO3? Please tell me. Thanks in advance. Best regards, Hansan Liu The State Key Lab for Physical Chemistry of the Solid Surface, Xiamen University,P.R.China E-mail:[EMAIL PROTECTED] _ ÏÄÈÕÊÝÉí¡¢°çö¦±¦µä http://shopping.263.net/hotsale/summer/ Á¸ÓÍÃ×ÃæÒûÁÏ£¬ËÍ»õÉÏÃÅ http://shopping.263.net/category19.htm
Betreff[2]: Li2SnO3
Re: spherical harmonics in GSAS question
Dear Sergey ( All), The default values of omega, chi phi (0,90,0), which you will find under 'A' in histogram editing, are appropriate for Bragg-Brentano diffraction geometry. For Debye-Scherrer geometry these should be set to (0,0,0). Since experience has shown that texture is rare for D-S data, changing these is rarely needed. The sample rotation angles found in the spherical harmonics texture menu are only needed for full texture analysis to correct for small sample orientation errors. If you tilt the sample then the appropriate values must be changed to reflect the rotation of the sample. See p141-144 of the GSAS Manual for a full description of the coordinate systems and Eulerian rotation angles used for spherical harmonics texture. Bob Von Dreele At 07:30 PM 5/30/01 -0800, you wrote: Dear All, Could somebody give me a hint on what should be omega, phi and chi angles ideally for Bragg-Bretano geometry (or tell why they should change)? Thanks in advance, Sergey -- Sergey Ushakov post-doc University of California at Davis Thermochemistry Facility Dept. of Chem.Engr.Mat.Sci. One Shields Ave., Davis, CA 95616 ph 530/754-5863 fax 530/752-9307
New GSAS
Hi, I have placed new Windows and Linux versions of GSAS on the ftp site. Changes are as follows 1. A new version (0.99.7a) of the GRWin library is now used. GSAS now uses the mscvrt version of the g77 libaries. The previous version used the crtdll libaries. Consequently the Windows behavior is changed for graphics. The GRWin window is now always on top (i.e. above the console other windows). Do not minimize or delete the GRWin window as that will cause the GSAS routine to crash if another plot is requested. Just slide the GRWin window off to one side or resize it to a postage stamp if it is in the way. 2. The cursor/keyboard now works correctly in all Win versions. 3. Eight simultaneous plots are allowed in all Windows versions of GSAS. The ninth plot overwrites the first, the tenth overwrites the second, etc. 4. gsas2cif now works and produces the calculated background correctly. 5. The line width for the Windows graphics routines has been increased. The resulting emf (encapsulated metafile) files can then be used to insert into a Word or PowerPoint document which will print nicely. A remaining mystery: 1. Empty files (expedt, genles, etc.) are created in Windows under certain conditions. Those of you who are using Win2000 please look at the readme file as there is an easier way to set the correct environment variables GSAS needs to run correctly. No more editing the autoexec.bat file. Please let me know of any problems. Bob Von Dreele
