Speaking of internal standards. Can someone recommend a source of bulk alumina to use for production samples. I don't find 'linde A' listed in the Buehler catalog anymore. I'm not sure which of the various grades they list to order or if there is a better place to order it.
Doug Allen Usually just lurking on this list -----Original Message----- From: Jim Cline [mailto:[EMAIL PROTECTED] Sent: Thursday, May 06, 2004 1:18 PM To: [EMAIL PROTECTED] Hi, At 03:48 PM 5/6/2004 -0400, you wrote: >Jim > >Excellent news! This amorphous standard issue has been driving me >nuts. When you say phase purity do you mean purity in terms of >crystalline phase content? Yes. Jim >Pam > >Dr Pamela Whitfield CChem MRSC >Energy Materials Group >Institute for Chemical Process and Environmental Technology Building >M12 National Research Council Canada >1200 Montreal Road >Ottawa ON K1A 0R6 >CANADA >Tel: (613) 998 8462 Fax: (613) 991 2384 >Email: <mailto:[EMAIL PROTECTED]> >ICPET WWW: http://icpet-itpce.nrc-cnrc.gc.ca > > >-----Original Message----- >From: Jim Cline [mailto:[EMAIL PROTECTED] >Sent: May 6, 2004 3:43 PM >To: [EMAIL PROTECTED] > > >Hi all, > >This is to say that I'm am nearly finished with the re-certification of >SRM 676 for amorphous content. The revised certificate, offering a >discussion as to the certification method, will be on the NIST website >shortly, after the review process is completed. The certified phase >purity of SRM 676 (retroactive to units in the field) is 91.75% +/- >1.5%. > >Regards, > >Jim > >At 01:44 PM 5/6/2004 -0400, you wrote: > >Robert > > > >As previously mentioned many Rietveld programs will do what you want > >if you're willing to do the amorphous content calculations by hand > >afterwards. Some commercial software has it built in. I've done work > >in this area, and there are some pitfalls of which you must be aware, > >or your results may be VERY unreliable. > > > >1. microabsorption. If your phases are similar in composition and > >your 'spike' phase has a similar absorption then this might not be a > >problem. However, there are instances in which extreme > >microabsorption can make a accurate determination practically > >impossible (other than possibly changing your tube to a more friendly > >wavelength). There is the Brindley correction that can sort of > >correct moderate microabsorption, but you need to know >your > >particle size, and ideally it needs to have a narrow distribution. >Reducing > >the particle size of your sample to sub-micron levels helps > >significantly. > > > >2. spike phase. Many so-called crystalline phases aren't as fully > >crystalline as you might think. The SRM676 alumina had it's > >amorphous content measured a while back using neutrons and came out > >as 1.77 +- 0.68%. It doesn't sound alot but can make a big difference > >to your final results. Many 'crystalline' phases can be significantly > >higher. Microabsorption can be an issue with the spike so choose > >your spike carefully, and ideally standardise it using SRM676. > >Remember to include the error in the SRM676 amorphous content if > >quoting absolute amorphous contents rather than relative amounts. > > > >3. particle statistics. This is equally as important when looking at >purely > >crystalline materials, but errors due to poor particle statistics can >really > >mess up amorphous content work. Ideally, micronise your sample > >before running it, but if they're nanomaterials then it might not be > >an issue. > > > >4. surface roughness. I noticed that you probably work with >nanomaterials. > >They tend to be fluffy, and such samples (at least on our instrument) > >show noticeable surface roughness effects on low angle reflections. > >If this is the case for your samples then you will either have to > >correct it or >densify > >your sample somehow (or both). > > > > > >Some of this stuff was covered in the results of the quantitative > >analysis round robin a while back: > > > >Outcomes of the International Union of Crystallography Commission on > >Powder Diffraction Round Robin on Quantitative Phase Analysis: > >samples 1a to 1h I. C. Madsen, N. V. Y. Scarlett, L. M. D. Cranswick > >and T. Lwin, J. Appl. Cryst. (2001). 34, 409-426 > > > >Outcomes of the International Union of Crystallography Commission on > >Powder Diffraction Round Robin on Quantitative Phase Analysis: > >samples 2, 3, 4, synthetic bauxite, natural granodiorite and > >pharmaceuticals N. V. Y. Scarlett, I. C. Madsen, L. M. D. Cranswick, > >T. Lwin, E. Groleau, >G. > >Stephenson, M. Aylmore and N. Agron-Olshina > >J. Appl. Cryst. (2002). 35, 383-400 > > > > > >It would be useful to cross-check your technique on a couple of dummy > >samples if at all possible to make sure you're not being mislead. > >Have fun!! > > > >Pam > > > > > > > >Dr Pamela Whitfield CChem MRSC > >Energy Materials Group > >Institute for Chemical Process and Environmental Technology Building > >M12 National Research Council Canada > >1200 Montreal Road > >Ottawa ON K1A 0R6 > >CANADA > >Tel: (613) 998 8462 Fax: (613) 991 2384 > >Email: <mailto:[EMAIL PROTECTED]> > >ICPET WWW: http://icpet-itpce.nrc-cnrc.gc.ca > > > > > >-----Original Message----- > >From: Robert Mauricot [mailto:[EMAIL PROTECTED] > >Sent: May 6, 2004 10:57 AM > >To: [EMAIL PROTECTED] > > > > > >Dear all, > > > >I have a powder diffraction of an amorphous multiphase material. I > >want to do a quantitative analysis of the amorphous phase. Can > >anyone tell me what software does it. > > > >Sincery > > > >R.mauricot > > > > > >Cemes-CNRS > >Toulouse 31077 France > >Laboratoire NaNomat > >James P. Cline [EMAIL PROTECTED] >Ceramics Division Voice (301) 975 >5793 >National Institute of Standards and Technology FAX (301) 975 5334 100 >Bureau Dr. stop 8520 >Gaithersburg, MD 20899-8523 USA James P. Cline [EMAIL PROTECTED] Ceramics Division Voice (301) 975 5793 National Institute of Standards and Technology FAX (301) 975 5334 100 Bureau Dr. stop 8520 Gaithersburg, MD 20899-8523 USA
