Components of the McCrone Associates Rigaku micro-XRD instrument.įor all samples, the source is operated at its maximum power of 40 kV/20mA. The tip of a glass rod is heated to melting and pulled to form a thinner fiber approximately 5-10 micrometers in size (Figure 1).įigure 4. At McCrone Associates, our glass fibers are manufactured in-house by our cleanroom staff. Typical powder diffraction instruments mount particles on glass fibers too large for particles in the 10 micrometer size range. The apparatus holding the sample must not be crystalline itself and it should not be a highly absorbing material both qualities would interfere with the sample pattern. Powder diffraction requires that the sample must have rotation in at least one direction using more than one rotation direction simultaneously is advantageous to allow as many crystallographic planes to be exposed as possible. Sample PreparationĪ focused X-ray beam requires that a sample be positioned precisely in its path. The instrument has successfully analyzed particles as “micro-powder” samples down to 6 micrometers in size. with the implementation of a Rigaku MicroMaxx-007 rotating anode source combined with the RAPID-SPIDER X-ray detector. These limits of particle analysis have been overcome at McCrone Associates, Inc. Another option is to analyze the particle at a synchrotron source, also not cost-effective and most likely inconvenient. More X-rays are needed to increase the diffraction probability. For samples in the 10 micrometer size range, the long time needed (10’s of hours) to produce enough diffraction events to create a usable XRD pattern would not be practical. While these tubes are low-cost and easy to maintain, their X-ray flux can only analyze samples 100’s of micrometers in size in a reasonable timeframe because of the low probability of a constructive diffraction event being detected. Typical powder instruments use sealed tubes to generate X-rays. Rotations in several directions expose planes in the sample’s crystal lattice multiple times and produce distinct, detectable diffraction events particular to the sample. The most common use of the X-ray diffraction phenomenon is in powder diffraction instruments where several randomly oriented crystals in a small amount of powder are rotated in an X-ray beam. X-ray diffraction (XRD) has been the indispensable tool for identifying crystal phases.
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