No abstract

The X-Ray diffraction (XRD) technique has been used to characterize crystalline phases in mixtures ever since its discovery. In contrast to the spectroscopy, it can provide quantitative phase information via Rietveld refinement [1]. While spectroscopy is commonly used to map surface elemental distributions, XRD has not been popular for such mapping applications-likely due to the lack of suitable instruments and analysis software. Nowadays, high brilliance and high energy synchrotron Xrays are available, that can penetrate relatively thick bulk materials. And with highly collimated micronsize beams, the technique can generate tens of thousands diffraction patterns in a few hours-which can cover a few cm 2 surface with sub-mm resolution. Quantitative analysis of such big data sets remains a challenge since most Rietveld refinement programs were not developed with such applications in mind.