The development of the powder profile refinement in the 1960s at the Reactor Centre at Petten, NL

What is it about?

It is about profile refinement, generally known as Rietveld refinement. In the 1960s at the Reactor Centre Netherlands at Petten, Bert Loopstra started a neutron-diffraction group and hired later Bob van Laar. Loopstra had the idea of using all the data points of a measured powder diagram to refine structural parameters. Van Laar worked it out mathematically and presented an example of fitting the full peak shape. Then Bert and Bob decided to wait for computer power and programming knowledge, of which neither had any experience. The computer power came in the form of the Electrologica computers, and the programming experience with Hugo Rietveld as new member of the group. In this paper the origins of profile refinement are explored. It is shown that the community should have recognised the merits of the inventor of the principle, instead of accepting the version of events as promoted by Rietveld, in which he claimed the idea came to him in a flash of inspiration.

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Why is it important?

With the recent passing of Hugo Rietveld, the death of Bert Loopstra in 1998 and before other pioneers disappear, it is important to set down the historically correct account. It is also important because the method is used daily in both neutron and X-ray powder diffraction with many thousands of references. Our paper shows clearly the correct historical account, which can be found by exploring the existing crystallographic literature about the subject.

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