Leandro, You probably should consult the references suggested by Alan Hewat and Reinhard Kleeberg before you read anything into your "reasonable" Rwp. Kaolinite is grossly over-parametized in your refinement strategy. If you are stuck with TOPAS, you may want to contact Arnt Kern (Bruker) about last year's TOPAS workshop. I recall that there was a paper on refinement strategies for disordered clays.
Dipo Omotoso CANMET Energy Technology Centre - Devon Energy Technology and Programs Sector Natural Resources Canada #1 Oil Patch Drive, Devon, AB. Canada Groupe des techniques perfectionnées de séparation Centre de la technologie de l'énergie de CANMET - Devon Secteur de la technologie et des programmes de l'énergie Ressources naturelles Canada -----Original Message----- From: Leandro Bravo [mailto:[EMAIL PROTECTED] Sent: Thursday, March 15, 2007 4:15 PM To: rietveld_l@ill.fr Subject: Re: Problems using TOPAS R (Rietveld refinement) Ok, I´m starting to have sucess in the kaolinite refinement, the quantification is giving me reasonable values. I´m refining the thermal factors, all the atoms positions in the kaolinite, the lattice parameters and the cystallite size. Lattice parameters and crystallite size are giving me very good numbers, with very low errors (about 0,09). In the thermal factors, I realized that alll of them tend to 20, so after all refinements I put them to 20, and refine all over again. I don´t care that much for atoms positions, I´m only using them because refining only lattice, thermal and cry size wasn´t enough to make a good calculated pattern to compare with the measured one. In the calcite and dolomite I refine: lattice parameters, cry size and thermal factors. And use on both a preferred orientation correction (spherical harmonics 4 th order). The RWP is about 16. I´d to hear some opinions about this strategy of refinement, if you think that I can spare some refining cycles or even fix some values to reduce erros in the refinement. _________________________________________________________________ Descubra como mandar Torpedos SMS do seu Messenger para o celular dos seus amigos. http://mobile.msn.com/
