Our presenter is Joe Swider of McCrone Associates. The com- mon method for quantitative texture analysis by X- rays diffraction (XRD) from a crystalline medium is based on the measurement of pole figures (PF) (.Charles Zona (CZ): Hi, my name is Charles Zona, and I’d like to welcome everyone to today’s McCrone Group webinar. Powder diffraction file (PDF) database Generally, ALL peaks found in a PDF pattern must also be seen in in the diffractogram, otherwise it is not a valid match Possible exceptions: Small peaks may be not detectable if the noise level is too high Missing peaks may be the result of a very strong preferred orientation effect (intensities. X-ray diffraction Powder techniques.
Joe Swider (JS): Hello, and good afternoon. It can tell us whether swelling. Knowing the clay mineral composition of the shale can be useful in drilling. Results are sensitive to variations in sample preparation as well as to irregularities in the sample. Modern instrumentation and automation gives fast results. Joe will field questions from the audience immediately following today’s presentation, and now, I will hand the program over to Joe.X-ray diffraction is widely used for the phase identification of a crystalline material and can provide valuable information.
Bragg’s description of diffraction by a crystal, although not physical, is useful to explain X-ray diffraction in an intuitive way and to provide a. The Fe3O4 nanoparticles were characterized by powdered X-ray diffraction (XRD), transmission electron microscopy (TEM).X-ray diffraction ii) the diffracted signal decreases with the scattering angle, therefore X-ray diffraction peaks at high scattering angles are on average weak iii) the latter effect is increased by static and dynamic positional disorder. I routinely look at samples using X-ray diffraction, and also scanning electron microscopy with energy dispersive X-ray spectrometry, or SEM/EDS.BibTex Kaynak Gster PDF. I have been with McCrone for almost 14 years in their electron optics group.
Another good example is calcium carbonate, a very common material. How the atoms are arranged in a sample can show very different physical properties, if you look at rutile, anatase, or brookite. The mass percent stays the same no matter how those atoms are arranged however, titanium dioxide can exist as at least three different forms. You can see, on the right side, the phase. You can also distinguish the degree, or if, something is crystalline or amorphous using x-ray diffraction.How is phase identification different than typical elemental identification? In elemental identification the question is, what is the amount of each element in the sample? For instance, on this slide, I have titanium dioxide. It’s commonly used for inorganics, but more and more is being used for organics, in particular, with pharmaceuticals.
If they interact constructively, it produces a bright line in a diffraction pattern. X-rays interact with materials as waves, and when they do this, they can interfere with each other, depending on the phase of the wave. Calcite, commonly known as chalk, is very different than aragonite, which is known to be a portion, or part of, mother-of-pearl.Now I will briefly explain a small amount of X-ray diffraction theory. Property-wise they are very different. Both of the samples, if they were analyzed using EDS or some other elemental technique, would show exactly the same amounts of calcium, carbon, and oxygen however, you can see—because the atoms are arranged differently—they look very different.
X Ray Diffraction Software To Translate
We use system software to translate the ring pattern to a 2θ versus intensity plot such as this. The center of that circle, where there is an “x,” is actually where the sample would be, and the diffraction pattern rings are outward from that center. The instrumentation we use at McCrone Associates uses a filmless film technique.This is an example of an XRD ring pattern, which many of you, if you’ve done XRD decades ago with photographic film, it looks about the same, or may be a little wider. They can be detected electronically through a charge coupled device (a type of camera), or they can be collected all at once on film. As the sample rotates, it does give off constructive interference, which are bright lines in a pattern and are detected.
We have two Rigaku micro XRD instruments, both instruments utilize a rotating anode, which is a high intensity x-ray source much higher than typical sealed tubes. The ICDD database is updated every year, and it has over 350,000 references.I would like to talk about the instrumentation we use at McCrone Associates for XRD. Almost all references by the International Center for Diffraction Data (ICDD), which is a database we use, is in the form of 2θ versus intensity. If you look at our XRD data, you can see that the first three peaks going from left to right between 20-30 are very intense, which of those three rings a smaller peak, which was the weaker ring, etc.We need to translate the XRD data from the image to the 2θ versus intensity for reference purposes.
Typically, particles are analyzed for SEM/EDS analysis first. The SEM image shows this more explicitly with a 9 µm particle adhered to the glass fiber, just using a simple adhesive.Now that these particles are mounted and we know how they are mounted, how would this fit into an analysis scheme? There are a couple of ways we can do it. For XRD, for particles, the cleanroom can draw out fiber optics to the size of about 5–10 µm for the mounting of small particles.Here’s an image of a tungsten needle mounting a particle onto one of these thin glass fibers. Our cleanroom can extract particles for various techniques, but also can mount them for XRD. Particles can be in hundred microns down to 10 µm in size, and the beam size for these both of the instruments is 100 µm.Now that we have this instrument, we utilize our exceptional cleanroom for extraction and mounting particles.
X Ray Diffraction Verification Of Phase
Usually, when something comes in for XRD, we will ask if you need elemental analysis, and what kind of data analysis do you need? Do you need a simple comparison to the ICDD? Do you need to know if it’s crystalline or amorphous? Or, do you have your own standard to compare to? Some common requests we get for analysis are pharmaceutical verification of phase. We can also work with particles that are extracted, or as a result of filtration, isolate them and analyze them on SEM/EDS and/or XRD. We can also look at surfaces or areas on large samples as pictured on the right.With particles, powders, and bulk, these are some of the types of samples we receive for analysis. We use a 100 µm beam, so the amount of sample we require is very little.
We look at contamination identification, corrosion products, paints and pigments, a wide variety of organics, and can determine crystallinity.
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