Dear Collages:
I can understand the difference in the form of the rocking curve for the cases of textured and un-textured materials. However, I would like to know if there is any way to discriminate between the possible cases of texture or graininess using the rocking curve or a set of rocking curves. Is any difference expected in both cases (texture and graininess)? Regards -------------------------------------------------------------- Angel L. Ortiz, PhD Associate Professor (Reader) Materials Science and Engineering Department of Mechanical, Energy and Materials Engineering University of Extremadura, Badajoz 06006, Spain (34) 924289600 Ext:86726 (Phone) (34) 924289601 (Fax) http://materiales.unex.es/miembros/personal/al-ortiz/index.html --------------------------------------------------------------- De: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] En nombre de Mikko Heikkilä Enviado el: viernes, 25 de octubre de 2013 10:56 Para: 'Angel L. Ortiz'; Rietveld_l@ill.fr Asunto: RE: rocking curve Dear Prof. Ortiz and other colleagues, that is a good question, I suppose I need to think that a bit more, but heres my quick feelings about that. Since I measure with point detector I measure just a slice from the full diffractogram I would see with a 2D detector, so I will get wrong intensities or even miss some reflections if the sample is textured or very grainy. If I see a reflection, set two theta to that angle and do a rocking curve (or equal omega scan), I will have a probability with respect to surface normal of finding crystallites with that lattice spacing. If I get a peak, then I have an oriented film. If its just constant background, Id say the crystallites causing that reflection are evenly distributed and theres no orientation, like in this case of mine. If I have a veeery low amount of crystallites, well, Im not sure what would happen. Since that rocking curve is in any case a sum of intensities of reflecting crystallites, I suppose very small amount of crystallites would cause the rocking to fluctuate in some manner (although I dont think Ill ever have that small amount of crystallites). Then again even for small amount but oriented crystallites it would give a peak, if all are oriented to same direction. Thats my thoughts, please correct me if Im totally mistaken with this. BR, Mikko From: Angel L. Ortiz [mailto:alor...@unex.es] Sent: 25. lokakuuta 2013 11:19 To: 'Mikko Heikkilä'; Rietveld_l@ill.fr Subject: rocking curve Dear colleagues How can one distinguish between texture and graininess using the rocking curve?. Which would be the expected difference in the rocking curve in each case? I am not clear on this. Regards -------------------------------------------------------------- Angel L. Ortiz, PhD Associate Professor (Reader) Materials Science and Engineering Department of Mechanical, Energy and Materials Engineering University of Extremadura, Badajoz 06006, Spain (34) 924289600 Ext:86726 (Phone) (34) 924289601 (Fax) http://materiales.unex.es/miembros/personal/al-ortiz/index.html --------------------------------------------------------------- De: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] En nombre de Mikko Heikkilä Enviado el: viernes, 25 de octubre de 2013 9:32 Para: Rietveld_l@ill.fr Asunto: phase id for Friday refreshment Dear Rietvelders, I decided to completely embarrass myself and ask you a simple phase identification question. Ive had some trouble in trying to figure out whats going on with one measurement done in our lab. The sample is a ~30nm film heat treated in air at 500C, composition is Ce:Sn in close to 1:1 ratio plus oxygen in addition to those. I cant tell if theres any very light elements as we only have EDX data at the moment, and the actual amount of O is still unclear due to 3-4nm of native SiO2 under the sample and I dont have any XPS/RBS/SIMS profile data yet. I cant find anything from our databases that would fit even remotely close to the measured data. (we have ages old PDF2 but Ive imported every CeOx, SnOx and CexSnyOz structure I could find from latest ICSD). Indexing is a bit frustrating as well since I cant be sure if its a single phase, and I dont have too much experience with unknowns anyway. The measurement was done in grazing incidence mode with 1deg incident angle (it seems that there was some 0.014deg of 2theta shift back then). Ive done rocking curve measurements from the first six reflections, based on that it doesnt seem to be textured so there shouldnt be reflections missing due to that (particle statistics is obviously a different matter ). When measuring with different incident angles (from 0.25 to 3.75 2th) the diffractograms dont seem to change, so theres probably no separate layers but one homogeneous matter. The data is found here for those interesting in trying: http://www.helsinki.fi/~mwheikki/temp/ And before you ask, theres no reflections below the one at 23.5 2th. And its a Cu tube. I really appreciate any effort and time any of you might spend with the data. Im currently trying to find something from the literature but no success so far. Hopefully you can make me feel stupid and find out the easy solution before I do J Have a nice weekend! BR, Mikko --- Mikko Heikkilä, M.Sc., Laboratory engineer Laboratory of Inorganic Chemistry Department of Chemistry P.O. Box 55 (A.I. Virtasen aukio 1) FI-00014 University of Helsinki phone: +358919150216 mobile: +358504160572 email: mikko.j.heikk...@helsinki.fi
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