### Question regarding FullProf limits for unit cell parameters

Dear all, I am currently trying to perform a simple refinement of Corundum in the hexagonal setting, namely the unit cell parameters (a=b=4.7589 A, c=12.991 A, alpha=beta=90 deg., gamma=120 deg): Refining the cell parameters a and c works without problems, and putting limits to the refinement of the parameter c also works as expected. However, when I try to add limits to the parameter a (=b) I am running into issues: The original value is a=4.7589 A, and I would like to add the following limits: Min=4.7 A, Max=4.8 A. Hence, I have added the following line in the pcr-file: ! Limits for selected parameters : 1 4.7 4.8 0. 0 Cell_A_ph1_pat1 After running FullProf, I found the following section in the .out-file: => The following parameter limits have been read: -> Parameter no.:1 Limits: 4.70004.8000 Step for SA & BoundaryCond: 0.0 -> Modified internal limit for cell parameter no.:1 Limits: 0.0 0.0 -> Modified internal limit for cell parameter no.:1 Limits: 0.0 0.0 -> Modified internal limit for cell parameter no.:1 Limits: 0.0 0.0 -- SYMBOLIC NAMES AND INITIAL VALUES OF PARAMETERS TO BE VARIED: -- -> Parameter number1 -> Symbolic Name: Cell_A_ph1_pat1 4.7589002 As you can see, the limits "Min=4.7 A" and "Max=4.8 A" have been read from the pcr-file, however, FullProf then seems to calculate "modified internal limits" for this parameter, and these are zero in this case. As you can imagine, the refinement does not work, of course. I have also tried the same for a cubic structure (in which case you also have "coupled" unit cell vector lengths); this worked without problems. I have searched the FullProf documentation as well as the tutorials and finally the web, but I could not find anything about it. Do you have any idea why this might happen? Am I doing something wrong? Thank you very much in advance! Holger Putz Crystal Impact Dr. H. Putz & Dr. K. Brandenburg GbR Kreuzherrenstr. 102 53227 Bonn Germany Tel . : +49-228-9813643 Fax : +49-228-9813644 E-mail: <mailto:i...@crystalimpact.de> i...@crystalimpact.de Web : <https://www.crystalimpact.de> https://www.crystalimpact.de ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++

### Cell parameters

Dear all I am looking for references about cell parameters of mixed orthoferrites of La and Y. (Y(1-x)LaxFeO3). I have crystal data for the end members of the serie but I can not find any reference about cell parameters of intermediate compositions. Any information would be useful. Many thanks, Susana Conconi Centro de Tecnología de Recursos Minerales y Cerámica M.B.Gonnet Argentina

### Le Bail vs Rietveld for crystallite size and cell parameters?

Dear All, I was wondering if there are any advantages of using Rietveld vs Le Bail refinements when crystallite size and cell parameters are the only variables of interest? Thank you, Sergey -- Sergey Ushakov PhD Staff Research Associate Peter A Rock Thermochemistry Laboratory and NEAT ORU University of California at Davis One Shields Avenue, Davis, CA 95616 phone (530) 754-5863 Fax (530) 752-9307 __ This message was written entirely with recycled electrons.

### Re: Le Bail vs Rietveld for crystallite size and cell parameters?

Hi ! I have worked with both methods in ZnO, I have found that it is easier work with Le Bail or Pawley when you are looking for size strain and lattice parameters, because you just need some data about the crystal structure. But this is just an specific case. Best wishes Miguel Hesiquio-Garduño Profesor Titular A Departamento de Ciencia de Materiales Academia de Ciencias de la Ingeniería ESFM-IPN. tel 57 29 60 00 ext. 55003, ext. 55011 Dear All, I was wondering if there are any advantages of using Rietveld vs Le Bail refinements when crystallite size and cell parameters are the only variables of interest? Thank you, Sergey -- Sergey Ushakov PhD Staff Research Associate Peter A Rock Thermochemistry Laboratory and NEAT ORU University of California at Davis One Shields Avenue, Davis, CA 95616 phone (530) 754-5863 Fax (530) 752-9307 __ This message was written entirely with recycled electrons.

### Re: Le Bail vs Rietveld for crystallite size and cell parameters?

Le-Bail and Pawley methods give extra freedom to intensities which may lead to adverse correlations between peak intensities and shape especially for noisy and overlapped data. In Rietveld refinement the intensities are restrained by the structure model and the instrument-related parameters, so if the parameters are chosen correctly you have a chance to reduce the correlations and obtain more accurate results. Unfortunately, it is not always easy to choose structural and instrumental parameters correctly enough. Anyhow, it is better to try both variants and see the difference that might give, besides, an estimation of the uncertainties. Regards, Leonid Solovyov Dear All, I was wondering if there are any advantages of using Rietveld vs Le Bail refinements when crystallite size and cell parameters are the only variables of interest? Thank you, Sergey __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

### Fwd: Re: [sdpd] Pt cell parameters versus temperature

The thermal evolution of the lattice parameters of Pt was discussed in 2005 on the SDPD list. One of the replies follows. Andy Subject: Re: [sdpd] Pt cell parameters versus temperature Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=lima; d=yahoogroups.com; b=CuDrO+yyy0Nh8qEUzQ0xiV4P0Iu8gngFyBiEnODlH+PJ7noFbaEKZRKf24kfnc/bhsnTFHQz/3B/nMQK/Yf9vD2LIint/8323+ezU77AXRLZC55KELYPO66uaWkNMQBS; X-Yahoo-Newman-Property: groups-email X-Sender: [EMAIL PROTECTED] X-Apparently-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] X-Originating-IP: 66.163.178.154 X-eGroups-Msg-Info: 1:12:0:0 From: Anatoliy Senyshyn [EMAIL PROTECTED] X-Yahoo-Profile: asenyshyn Sender: [EMAIL PROTECTED] Mailing-List: list [EMAIL PROTECTED]; contact [EMAIL PROTECTED] Delivered-To: mailing list [EMAIL PROTECTED] List-Id: sdpd.yahoogroups.com List-Unsubscribe: mailto:[EMAIL PROTECTED] Date: Thu, 13 Oct 2005 09:10:31 -0700 (PDT) Reply-To: [EMAIL PROTECTED] Dear Guilhem, on answer to your interest in the lattice parameters of platinum for high temperature: T(C) a(A) 25 3.924 171.7 3.930 350.6 3.935 459.3 3.939 586.7 3.944 698.2 3.948 797.7 3.952 904.9 3.957 960.7 3.959 1027.5 3.962 1104.8 3.966 1154.3 3.969 1233.5 3.973 1267.1 3.975 1293.0 3.977 1300.8 3.978 1339.5 3.980 The uncertainty of values have been found ca. 0.001 A approximately. These data were taken from preprint of Bouchaib Manoun, Surendra K. Saxena, and Hanns-Peter Liermann Thermal Expansion of Polycrystalline Ti3SiC2 in the 25114001C Temperature Range J. Am. Ceram. Soc., 00 [0] xx (2005). Also I can recommend to see: 1. http://nvl.nist.gov/pub/nistpubs/jres/091/6/V91-6.pdfhttp://nvl.nist.gov/pub/nistpubs/jres/091/6/V91-6.pdf 2. James W. Edwards, Rudolph Speiser, and Herrick L. Johnston High Temperature Structure and Thermal Expansion of Some Metals as Determined by X-Ray Diffraction Data. I. Platinum, Tantalum, Niobium, and Molybdenum Journal of Applied Physics -- April 1951 -- Volume 22, Issue 4, pp. 424-428 3. G K White Thermal expansion of platinum at low temperatures J. Phys. F: Met. Phys. 2 L30-L31 You can calculate thermal dependence of lattice parameters from the thermal dependence of expansion coefficient presented in Refs. 13 via V-T equation of state: a(T)=a(T0)*exp(int(alpha(x),dx,T0,T)), where a(T0) means the known lattice parameter at fixed temperature T0, alpha(T) - thermal expansion coefficient, int(alpha(x),dx,T0,T) - integration of thermal expansion coefficient alpha(x) over x from T0 to temperature T. Good luck, Anatoliy Senyshyn --- Guilhem DEZANNEAU [EMAIL PROTECTED] wrote: Hello i am searching for Platinum cell parameters evolution versus temperature. thanks a lot Guilhem ___ Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger Téléchargez cette version sur http://fr.messenger.yahoo.comhttp://fr.messenger.yahoo.com __ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.comhttp://mail.yahoo.com SPONSORED LINKS http://groups.yahoo.com/gads?t=msk=Sciencew1=Sciencew2=Powderw3=Physicsw4=Physic+readerc=4s=57.sig=UmdE2tefuTt7TpRFnaoqlQScience http://groups.yahoo.com/gads?t=msk=Powderw1=Sciencew2=Powderw3=Physicsw4=Physic+readerc=4s=57.sig=SBXZA6gDDVEdRB-hwfXlfgPowder http://groups.yahoo.com/gads?t=msk=Physicsw1=Sciencew2=Powderw3=Physicsw4=Physic+readerc=4s=57.sig=fuWZcMmNALIwuXNOQNhSRAPhysics http://groups.yahoo.com/gads?t=msk=Physic+readerw1=Sciencew2=Powderw3=Physicsw4=Physic+readerc=4s=57.sig=_03sEdzC_vZcyJK_SP7f-wPhysic reader -- YAHOO! GROUPS LINKS * Visit your group http://groups.yahoo.com/group/sdpdsdpd on the web. * * To unsubscribe from this group, send an email to: * mailto:[EMAIL PROTECTED][EMAIL PROTECTED] * * Your use of Yahoo! Groups is subject to the http://docs.yahoo.com/info/terms/Yahoo! Terms of Service. --

### GSAS and cell parameters refinement

Dear all, Is it possible, in GSAS, to refine only one (or two...) of the cell parameters? If yes, is there anyone that can explain me how to do? Thank you very much Riccardo Vivani Dipartimento di Chimica Perugia - ITALY

### Re: GSAS and cell parameters refinement

Dear Riccardo, You can do this indirectly by fixing (y l o l f) the parameters you wish to keep constant. I believe that RM11, RM22 and RM33 are likely to correspond to you lattice parameters, and the cross terms to your angles. However my memory is hazy, but if you have a quick play about it should become clear. Jonathan. On Tue, 22 May 2001, Riccardo Vivani wrote: Dear all, Is it possible, in GSAS, to refine only one (or two...) of the cell parameters? If yes, is there anyone that can explain me how to do? Thank you very much Riccardo Vivani Dipartimento di Chimica Perugia - ITALY * * Jonathan Burley * * Inorganic Chemistry Laboratories* * South Parks Road* * Oxford * * OX1 3QR * * (01865) (2)72602* * e-mail : [EMAIL PROTECTED] * *