(Certain commercial equipment, instruments, or materials are identified in this in order to adequately specify the experimental procedure. ![]() The lanthanum hexaboride feedstock for SRM 660c was manufactured for NIST with a dedicated processing run (H.C Starck GmbH, Goslar, Germany, now Höganäs AB, SE-263 83 Höganäs, Sweden). It is commonly used for determination of the instrument contribution to the observed line profile, the instrument profile function (IPF), and calibrating powder diffractometers with respect to line position. It consists of approximately 6 g of lanthanum hexaboride (LaB 6) powder specifically prepared to have minimal line broadening. This report describes SRM 660c, the fourth generation of this powder diffraction standard, which is certified with respect to lattice parameter. The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of powder diffractometer performance. One method to accomplish this is to use standards to evaluate instrument performance. However, to successfully collect and interpret the data, the operator must have both a properly aligned instrument and take into consideration the aberrations inherent to the para-focusing optics. The laboratory-based divergent-beam X-ray diffractometer can provide a wealth of structural and microstructural information about a wide variety of materials. Both Type A, statistical, and Type B, systematic, uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 ☌ of a = 0.415 682 6 ± 0.000 008 nm (95% confidence). A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the LaB 6 powder. The microstructure of the LaB 6 powder was engineered specifically to yield a crystallite size above that where size broadening is typically observed and to minimize the crystallographic defects that lead to strain broadening. So that this SRM would be applicable for the neutron diffraction community, the powder was prepared from an isotopically enriched 11B precursor material. It is certified with respect to lattice parameter and consists of approximately 6 g of lanthanum hexaboride (LaB 6) powder. ![]() This report describes SRM 660c, the fourth generation of this powder diffraction SRM, which is used primarily for calibrating powder diffractometers with respect to line position and line shape for the determination of the instrument profile function (IPF). The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to evaluate specific aspects of instrument performance of both X-ray and neutron powder diffractometers.
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