Commission on Powder Diffraction

D. K. Smith and R. J. Hill. (Photo WLD)

Proposed Round Robin Project on Quantitative Phase Analysis

The difficulties of quantification by diffraction methods in the past have been the limited accuracy available when using individual peaks or peak clusters in the analysis. In the last ten years, whole pattern methods have been developed to eliminate the difficulties of decomposing the peak overlaps to acquire the necessary intensity information when using a limited number of peaks. Whole-pattern fitting, Rietveld analysis and combinations of these methods have shown considerable promise toward improvement of accuracy. With the increased application of these new approaches, it is now time to test the new procedures to determine the limiting factors which affect the accuracy under a variety of conditions.

During this next triennium, the CPD will be organizing and initiating a round-robin project on phase quantification by diffraction methods. The project will be designed to test the preparation of samples, the collection of the data, and the analysis of the data by the variety of programs that are available. We invite input from interested individuals concerning design of the project. We would appreciate suggestions as to the types of tests that should be performed and the types of samples that should be included. We would also like to hear from potential participants who would be interested in performing the necessary tests.

Input may be directed to D. K. Smith, Dept. of Geosciences, Pennsylvania State U., University Park, PA 16802, USA. FAX: 814-863-7845, e:mail: smith@vax1.mrl.psu.edu.

Conferences and Workshops

An International Workshop on "Advanced Powder Diffraction Techniques in Mineral and Materials Processing", Pretoria, South Africa, October 1994, organized by the South African Crystallography Society and the Mineralogical Association of South Africa. CPD member Lynn McCusker is the Chairman of the Scientific Program Committee.

A Workshop on "Ab initio Determination of Crystal Structure from Powder Diffraction Data," Oxford, July 1995, was organized by Bill David of the Rutherford Appleton Laboratory, UK.

A survey on the determination of crystallite size and microstrain from powder diffraction data, co-organized with the ICDD, was run in conjunction with the International Conference on Powder Diffraction, Liptovsky Mikulos, Slovakia, August 1995 (PMCS-95). CPD member Jaroslav Fiala is the Chairman of the Scientific Program Committee.

I take this opportunity to express the gratitude of CPD members to Ray Young for his superb Chairmanship of the CPD during its first six years.