Structural refinements of the individual grains within polycrystals and powders

A method is presented for simultaneous structural refinement of up to several hundred grains inside powders or polycrystals. The method is based on the use of hard X-rays and the indexing program GRAINDEX, where grain orientations are found by scanning in Euler space. Conventional experimental setups and refinement programs for single-crystal work can be applied. The method is validated by a study of a sintered plate of α-Al 2 O 3 , containing of the order of 1500 grains in the gauge volume. 57 of the largest grains were refined with respect to the Alz and Ox positions as well as the isotropic atomic displacement parameters. The R1 values were 3.4% and 3.8% for the grain average and the best grain, respectively. A discussion of the potential of the method is presented, as well as the main limitation: grain size and overlap of diffraction spots.

[1]  J. Janin,et al.  Macromolecular crystallography with synchrotron radiation: photographic data collection and polarization correction , 1982 .

[2]  Christian Baerlocher,et al.  An Ordered Form of the Extra-Large-Pore Zeolite UTD-1: Synthesis and Structure Analysis from Powder Diffraction Data , 1999 .

[3]  Henning Friis Poulsen,et al.  Tracking: a method for structural characterization of grains in powders or polycrystals , 2001 .

[4]  Lynne B. McCusker,et al.  Rietveld refinement guidelines , 1999 .

[5]  R. J. Hill,et al.  The electron distribution in corundum. A study of the utility of merging single‐crystal and powder diffraction data , 1993 .

[6]  Maria Cristina Burla,et al.  EXPO: a program for full powder pattern decomposition and crystal structure solution , 1999 .

[7]  E. Lauridsen,et al.  Kinetics of individual grains during recrystallization , 2000 .

[8]  K. Harris,et al.  Contemporary Advances in the Use of Powder X-Ray Diffraction for Structure Determination. , 2001, Angewandte Chemie.

[9]  R. Blessing,et al.  An empirical correction for absorption anisotropy. , 1995, Acta crystallographica. Section A, Foundations of crystallography.

[10]  H. Poulsen,et al.  In Situ Measurement of Grain Rotation During Deformation of Polycrystals , 2001, Science.

[11]  McCusker,et al.  Single-crystal-like diffraction data from polycrystalline materials , 1999, Science.

[12]  Manfred S. Weiss,et al.  Global indicators of X-ray data quality , 2001 .

[13]  D. Juul Jensen,et al.  Three-dimensional maps of grain boundaries and the stress state of individual grains in polycrystals and powders , 2001 .

[14]  Maria Cristina Burla,et al.  On the Number of Statistically Independent Observations in a Powder Diffraction Pattern , 1995 .

[15]  R. Blessing.  Outlier Treatment in Data Merging , 1997 .

[16]  R. Dreele.  Combined Rietveld and stereochemical restraint refinement of a protein crystal structure , 1999 .