Vibrating Sample Holder for Xrd Analysis with Minimal Sample Preparation

A new approach to sample handling for powder X-ray diffraction analysis is presented that allows characterization of poorly prepared samples. The technique relies on vibrations generated in a sample holder to create movement of the powdered sample in the absence of macroscopic movement of the sample holder itself. The major benefits over conventional sample handling strategies are: 1) the ability to characterize materials with grain sizes up to two orders of magnitude larger than previously possible without degradation of the data; and 2) ease of loading and removal of the samples, with no requirement for complex mechanisms. The Vibrating Sample Holder technique was demonstrated in a laboratory XRD instrument as well as in a miniature XRD/XRF instrument intended for robotic planetary exploration by NASA. A dramatic improvement in data quality for coarse-grained materials was observed, yielding accurate and reproducible intensity data for such materials. The Vibrating Sample Holder will be implemented in CheMin, an XRD/XRF instrument that will be included in NASA’s Mars 2009 Mars Science Laboratory mission. During its 2-year deployment on Mars, the MSL ’09 rover will conduct organic, chemical and mineralogical analyses of the Mars surface. CheMin will perform quantitative mineralogical analyses of powders delivered by an on-board rockcrusher, with no need for further grinding. The vibrating sample holder technique will be useful for a wide range of applications in which difficult samples are encountered, such as: very small amounts of material, as-received or grinding-intolerant material, process control, remote field analysis, etc.