Mario, You may want to check for the presence of solid solution in your siderite (especially Ca and Mg). In my experience refining the PO in siderite with measurable amounts of Ca or Mg correlates significantly with the occupancy if the Fe/(Ca or Mg) ratio is not constrained to the true chemistry. The chemistry may be estimated by the d104 shift.
Dipo Omotoso Natural Resources Canada CETC-Devon #1 Oil Patch drive, Devon AB. T9G 1A8. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Mon 10/27/2008 7:10 PM To: [EMAIL PROTECTED]; Rietveld_l@ill.fr Subject: RE: Quantitative analysis Dear Mario, Please tell me a little about the data collection conditions you used for this work:- How was the sample prepared (hand ground, micronised in McCrone mill ????) What was the tube target Cu, Co, other ?? Cheers Ian Madsen ________________________________________ From: [EMAIL PROTECTED] [EMAIL PROTECTED] Sent: Tuesday, October 28, 2008 2:48 AM To: Rietveld_l@ill.fr Subject: Quantitative analysis Dear all, I have this question, I have been refined one mixture (of well-know percentage composition) of CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in CaCO3 (104) and CaF2 (111) with good results. When I add to the mixture FeCO3 and I refine with preferential orientation (104), it happens that when I don´t apply the preferential orientation in all this phases, I have correct values of percentage composition, but when I apply the preferential orientation the refinement is good but with incorrect values of percentage composition. This experiment has been taken in Bragg Brentano geometry. How I should refine this mixture? Thanks a lot by your help. Mario Macías Universidad Industrial de Santander Colombia
