Hi all, The certification of SRM 660b has been completed and the paperwork is in the final stages of review, etc. This process typically takes no longer than a couple of months. The new SRM has been prepared with a dedicated processing run to synthesize LaB6 with the 11boron isotope enriched to a nominal 99% concentration . This will render the SRM relevant to the neutron scattering community. I have a gentlemen's agreement with the vendor that performed the annealing for us to not discuss the specifics of the process; however, the temperature was in the "high teens", dwell time is critical, and a specialized atmosphere was required. The necessity, or lack thereof, of using this SRM is entirely dependent on the application. Measuring material of 20 nm crystallite size on a laboratory diffractometer does not require a terribly good knowledge of the IPF.
My, rather limited, experience with D8 area detectors with a mirror optic (graphite monochromator???) is that the chief problem is particle counting statistics and you are better off using SRM 1976a or 640d. These materials having a lower attenuation (by an order of magnitude) than LaB6 and they display a sufficiently small degree of sample induced broadening that, for this application, they are acceptable for determining the IPF. Regards, Jim James P. Cline Ceramics Division National Institute of Standards and Technology 100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ] Gaithersburg, MD 20899-8523 USA jcl...@nist.gov (301) 975 5793 FAX (301) 975 5334 From: Wing Fai Lai [mailto:wfla...@yahoo.com] Sent: Thursday, February 18, 2010 7:50 PM To: Rietveld_l@ill.fr Subject: Intrumental broadening of 2D detector Dear list members, I'm a beginner in XRD and now trying to estimate the instrumental broadening. My final goal is to measure crystallite size and microstrain of minerals. The equipment I've is Bruker D8 discover with GADDS(2D detector) and XYZ stage. I know this is not a setup for high resolution diffractometry but that's what I have in my lab. I'm unable to get NIST 660 because they have been out of stock for a few months. I've NIST 640d, is it good enough for estimating instrumental broadening or I should prepare LaB6 from heating LaB6(from Sigma) over 300C? Otherwise, do anybody know where can I get 660? My current setup is: 45kV, 45mA, copper anode, graphite monchromator, 30cm detector distance, theta1,theta2 starting at 8 degree, both move at 0.5 step size, to 45degree ,collection time=300s, 0.05mm monocap. After merging the frames, I just integrate the middle part of frames. Is this setup okay or what should be improved? Thanks a lot. Regards, wing fai
