X-RAY-POWDER DIFFRACTION ANALYSIS OF SILVER BEHENATE, A POSSIBLE LOW-ANGLE DIFFRACTION STANDARD

Silver behenate, a possible low-angle diffraction standard, was charac terized using the powder diffraction technique. Diffraction patterns o btained with 1.54 angstrom synchrotron and Cu Kalpha radiations showed thirteen regularly spaced (001) peaks in the range 1.5-20.0-degrees 2 theta. With the National Institute of Standards and Technology's stand ard reference material silicon as an internal standard, the long spaci ng of silver behenate was accurately determined from the profile-fitte d synchrotron diffraction peaks, with d001 = 58.380 (3) angstrom. This result was in agreement with that obtained from the Cu Kalpha pattern . The profile widths of the silver behenate peaks were found to be con sistently larger than those of the silicon peaks, indicating significa nt line broadening for silver behenate. The average crystallite size a long the long-spacing direction of silver behenate was estimated using the Scherrer equation, giving D(avg) = 900 (50) angstrom. Because sil ver behenate has a large number of well defined diffraction peaks dist ributed evenly in the 1.5-20.0-degrees 2theta range, it is suitable fo r use as an angle-calibration standard for low-angle diffraction. Howe ver, care must be taken if silver behenate is to be used as a peak-pro file calibration standard because of line broadening.