CHARACTERIZATION OF CERAMIC MATERIALS WITH BIGDIFF - A SYNCHROTRON-RADIATION DEBYE-SCHERRER POWDER DIFFRACTOMETER

Experiments have been conducted to evaluate the potential of the BIGDI FF Debye-Scherrer diffractometer (radius of 573 mm) for characterizing ceramic materials using synchrotron radiation, The instrument has bee n tested at a wavelength of 0.1538 nm (1.5378 Angstrom), under in vacu o conditions, with standard reference materials and an alumina-matrix ceramic specimen using capillary-mounted (diameter of 0.5 mm) powdered material. The diffraction patterns that have been recorded with imagi ng plates over a period of 15 min provide phase detectability that is clearly superior to Bragg-Brentano laboratory X-rag diffractometry dat a that is collected in 1 h., The superiority of BIGDIFF for the analys is of phase composition becomes very pronounced for trace phases (<1%) , The sharper definition of the Bragg peaks with BIGDIFF synchrotron r adiation data also leads to improved estimates of nonlinear residual s train and crystallite size data, The superior performance of BIGDIFF i s principally due to (i) the intensity of the synchrotron radiation in cident beam that is achieved with high collimation and monochromaticit y (E/Delta E approximate to 10(4)), (ii) the large ratio of the camera radius to the capillary radius, and (iii) the spatial resolution and dynamic range of the imaging plates.