Location and Schedule

8:00 hs – 9:00 hs: “Advanced Materials Characterization Using Powder Diffraction Techniques and the Powder Diffraction File”. Dr. Thomas Blanton, Executive Director, International Centre for Diffraction Data (ICDD).

9:00 a.m. – 10:05 a.m. (2 lectures, 2 practice sessions): Introduction to X-ray diffraction from single crystals and powders. Results from diffraction experiments and CIF files. X-ray powder diffraction uses for the identification of crystalline phases. Lattice. Unit cell parameters. Atomic coordinates. Bragg’s law. Finite symmetry elements and operations. Crystal systems. Bravais lattices. Reciprocal lattice. Miller indices. Crystal structure solution and refinement overall procedure and free-distribution software used.

10:15 a.m.– 11:40 a.m. (2 lectures, 1 practice session): Indexing powder diffraction patterns. Quadratic formulas. Figures of merit. Indexing practice using free-distribution software (EXPO2014, DICVOL, and McMAILLE).Symmetry in crystals. Asymmetric unit. Infinite symmetry elements and operations. Combination of symmetry operations. Proper and improper symmetry elements and operations. Point groups and space groups of symmetry. International Tables for Crystallography. Systematic absences.

11:50 a.m. – 1:00 p.m. (2 lectures, 2 practice sessions): Practice on determination of the space group symmetry using EXPO2014 and other software.Instrumentation and data collection. Laboratory X-ray powder diffraction (XRPD) with Bragg-Brentano optics. Introduction to X-ray sources, monochromatization, and detectors. Selection of the scan mode, range, step size, and counting time. Synchrotron X-ray powder diffraction. Data aberrations and systematic errors in laboratory diffractometers.

1:00 p.m. – 2:00 p.m. – Lunch break.

2:00 p.m. – 3:40 p.m. (2 lectures, 2 practice sessions): Structure factors. Fourier transform.  Phase problem. Atomic scattering factor, occupancy factor, Debye-Waller factor, atomic displacement parameters. Powder diffraction step intensities and integrated intensities of the reflections. Peak profile functions in X-ray powder diffraction. Exact and partial overlap of diffraction peaks. Whole pattern decomposition methods and extraction of integrated intensities. Practice on the extraction of integrated intensities using EXPO2014.

3:50 p.m. – 5:15 p.m. (1 lecture, 2 practice sessions): Crystal structure solution and refinement steps. Brief overview of direct methods. Direct-space methods to solve crystal structures from powders. Parameterization of the crystal structure solutions. Global optimization algorithms. Available software and overall structure solution steps.Crystal structure solution of divanillin and 2-ethoxybenzamide using direct methods in EXPO2014. Crystal structure solution of phentolamine (direct-space methods).

Tuesday, December 2

9:00 a.m. – 10:35 a.m. (1 lecture, 2 practice sessions): An introduction to the Rietveld method. The residual. Rietveld agreement factors and criteria of fit. Linear and non-linear least squares minimization. Normal equations. Rietveld refinement strategy. Variances and covariances. Constraints and restraints. Practice on a Rietveld fit of LaB₆ line shape standard and the generation of a parameter file for GSAS-II (laboratory X-ray powder diffractometer). Rietveld refinement of 2-ethoxybenzamide with GSAS-II. Soft bond length and bond angle restraints. Refinement of atomic positions and atomic displacement parameters. Visualization of the structure (Mercury software) and generation of a CIF file.

10:45 a.m. – 12:20 p.m. (2 practice sessions): Rietveld refinement of phentolamine using GSAS-II. CIF preparation and validation (PLATON).

12:20 p.m. – 1:20 p.m. – Lunch break.

1:20 p.m. – 2:50 p.m. (2 lectures, 1 practice): The Cambridge Structural Database, software and uses.

2:55 p.m. – 3:25 p.m. (1 lecture): Crystal Explorer software and uses.