Re: quantitative analysis - perovskites - preferred orientation

2014-02-06 Thread Leonid Solovyov
Dear Lukasz, First of all, in the majority of Rietveld programs the uniaxial preferred orientation (such as [100]) can not be handled adequately for cubic systems since the programs normally generate only one symmetrically equivalent hkl for a diffraction peak. In DDM, for such cases, I include

RE: Quantitative analysis

2008-10-29 Thread Daniel Chateigner
hi all, not only fibre like, but single component fibre, and with the fibre axis parrallel to the sample normal (i.e. "cyclic fibre". this is very restrictive and generally does not correspond to the real texture. Contrarilly to what has been said here or there, the March-Dollase does not ensure P

Re: Quantitative analysis

2008-10-29 Thread Radovan Cerny
[EMAIL PROTECTED] a écrit : Hi Blaise In Bragg-Brentano mode, sample spinning does nothin for PO. This is because the diffraction vector is normal to the sample surface, and sample spinning rotates along this vector. That's wrong! As I have already written, the empirical PO corrections li

RE: Quantitative analysis

2008-10-28 Thread Matthew.Rowles
8892 Fax: +61 3 9562 8919 (site) Email: [EMAIL PROTECTED] From: Mibeck, Blaise [mailto:[EMAIL PROTECTED] Sent: Wednesday, 29 October 2008 01:25 To: rietveld_l@ill.fr Subject: RE: Quantitative analysis I am learning QPA and am worried about PO. I wonder why s

RE: Quantitative analysis

2008-10-28 Thread Martin
Spinning the sample doesn't reduce preferred orientation much. It does, however, improve ones counting statistics very nicely. Martin M Vickers Dept. of Chemistry UCL 20, Gordon Street London WC1E 0HX Subject: RE: Quantitative analysisDate: Tue, 28 Oct 2008

RE: Quantitative analysis

2008-10-28 Thread mariomacias
ipo Omotoso > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: October 28, 2008 8:24 AM > To: Rietveld_l@ill.fr > Subject: RE: Quantitative analysis > >>Dear all, > > the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3

RE: Quantitative analysis

2008-10-28 Thread Omotoso, Oladipo
:24 AM To: Rietveld_l@ill.fr Subject: RE: Quantitative analysis >Dear all, the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3 (20%), and FeCO3 (24%). The data obtained without PO are: CaCO3 (24%), CaF2 (36%), SiO2 (1%), Al2O3 (17%), and FeCO3 (23%). The data obtained with PO are

Re: Quantitative analysis

2008-10-28 Thread Radovan Cerny
in; [EMAIL PROTECTED]; rietveld_l@ill.fr *Subject:* RE: Quantitative analysis I agree that it's always best to avoid preferred orientation, but that is easier said than done on a routine basis. I have personally had good luck with the M-D PO correction on many known samples, as long as the PO

RE: Quantitative analysis

2008-10-28 Thread Mibeck, Blaise
n has nearly always led to poor quant results for me. It most certainly cannot be applied safely. Martin -- M Vickers Dept of Chemistry UCL ________ > Subject: Re: Quantitative analysis > Date: Tue, 28 Oct 2008 02:5

RE: Quantitative analysis

2008-10-28 Thread mariomacias
>Dear all, the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3 (20%), and FeCO3 (24%). The data obtained without PO are: CaCO3 (24%), CaF2 (36%), SiO2 (1%), Al2O3 (17%), and FeCO3 (23%). The data obtained with PO are: CaCO3 (19%), CaF2 (32%), SiO2 (2%), Al2O3 (31%), and FeCO3 (16%).

RE: Quantitative analysis

2008-10-28 Thread David L. Bish
poor quant results for me. It most certainly cannot be applied safely. Martin -- M Vickers Dept of Chemistry UCL -- > Subject: Re: Quantitative analysis > Date: Tue, 28 Oct 2008 02:53:20 -0700 > From: [EMAIL PROTECTED] > To: Rietveld_l

RE: Quantitative analysis

2008-10-28 Thread Whitfield, Pamela
998-8462Fax: (613) 991 2384 Email: [EMAIL PROTECTED] -Original Message- From: Leonid Solovyov [mailto:[EMAIL PROTECTED] Sent: October 28, 2008 5:53 AM To: Rietveld_l@ill.fr Subject: Re: Quantitative analysis Dear Mario, One more possible problem of applying preferred orientation cor

RE: Quantitative analysis

2008-10-28 Thread mariomacias
Dear all, The data collection conditions is: hand grind (35 microns), scan: 2Theta/Theta Coupled, to steps 2 sec., target Cu, graphite monochromator, side loading. The correction of preferential orientation has been refined by March-Dollase model. Thanks a lot, Mario. Dear Mario, > > Please

RE: Quantitative analysis

2008-10-28 Thread Omotoso, Oladipo
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

Re: Quantitative analysis

2008-10-28 Thread Radovan Cerny
> Subject: Re: Quantitative analysis > Date: Tue, 28 Oct 2008 02:53:20 -0700 > From: [EMAIL PROTECTED] > To: Rietveld_l@ill.fr > > Dear Mario, > > One more possible problem of applying preferred

RE: Quantitative analysis

2008-10-28 Thread Martin
Sorry to disagree. Experience tells me otherwise - the March-Dollase correction has nearly always led to poor quant results for me. It most certainly cannot be applied safely. Martin -- M Vickers Dept of Chemistry UCL > Subject: Re: Quantitat

Re: Quantitative analysis

2008-10-28 Thread Leonid Solovyov
Dear Mario, One more possible problem of applying preferred orientation corrections in QPA is that not all of them are normalized. For example, the March-Dollase correction is normalized and can be applied safely, but the Rietveld-Toraya correction is inapplicable to QPA as it does not preserve

RE: Quantitative analysis

2008-10-27 Thread Martin
Dear Mario, My experience of quant Rietveld is much the same as yours - poor quant result if using any sort of PO function. Advise as others have here - reduce PO. Capillary geometry may help in many instances but in this case could then have problems with absorption seeing as you will most like

RE: Quantitative analysis

2008-10-27 Thread Ian.Madsen
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 PROTECTE

RE: Quantitative analysis

2008-10-27 Thread Kurt Leinenweber
Dear Mario, If the quantity of FeCO3 appears to be smaller than the actual value, then it could be due to absorption. If you are using a copper source (CuKalpha) then that excites iron fluorescence, which is radiated equally in all directions... this means that the beam does not penetrate the

Re: Quantitative analysis

2008-10-27 Thread gregor
Dear Mario, I only use PO to check if it applies. If yes, I make a new preparation to avoid PO. Also, graininess may look similar to PO, and this would surely bias QPA if PO refinement is allowed for. So my advice is: grind, grind, grind. Best miguel On 27 Oct 2008 at 10:48, [EMAIL PROTECTE