LINX Learning


What is a material?
Materials in material’s science are often solids. We may find these solids all around us, in for example smartphones, cars, pots, and pans. Solids are composed of atoms in a three-dimensional lattice as shown in figure 1 below. Solids in an ordered lattice are known as crystalline materials or simply crystals. The lattice structure of these materials may give them a span of different properties, they can for example be magnetic, conductive, or isolating.

3D gitter
Figure 1: 3D lattice.
Credit: Prolineserver, CC BY-SA 3.0, via Wikimedia Commons

What is crystallography?
Crystallography is the science of crystal’s composition and structure. Crystallographers explore crystals through X-ray experiments. By shooting X-rays into a crystal scientist can learn something about its inner build. Crystallography can explore where atoms are positioned in a crystal lattice, their respective properties, and states.

What are X-rays?
X-rays are a type of light that cannot be seen by the naked eye. Light is defined by its energy. X-rays have more energy than the light we know from our daily lives. Measurements and experiments in crystallography use changes in X-rays’ very specific energy, direction or angle as an examining tool.

What is imaging?
X-ray techniques are some of the most used for imaging. X-rays can be used on objects where there are areas through which the rays penetrate and areas where they are blocked. X-rays can be blocked by certain metals or other massive materials. X-rays have therefore become widely popular in medicine. The rays are not blocked by skin, muscles, or fat, but by bones. By exploiting that fact about X-rays scientists have developed imaging techniques.


Celebrating Crystallography – An animated adventure
This video gives a short run-through of the history of crystallography’s history and usage. From 1913, where father-son researcher team were the first to shoot an X-ray onto a salt-crystal, to the Mars Rover which today does crystallographic experiments in space. An animated and humoristic approach to a complicated scientific subject.

What is Crystallography?
This video gives a light introduction to crystallography and X-rays. The video is in stop motion and uses a good mix of humor, drawing to explain the origin of X-rays what scientists use the techniques for.

SINE2020 and ILL, Small Angle Neutron Scattering
This video is a drawn stop motion video that explains how scientists use neutrons and the small angle scattering technique to find the shape and size of particles in shampoo. The video also gives a wider sense of what scientists also use neutrons for.

Mars Diffracts! X-ray Crystallography and Space Exploration
This video is a short documentary on how X-rays are used to explore the Martian surface. X-rays help with the analysis of the surficial composition and structure of Martian rocks with the Mars Rover as pilot.

Digital Sandstone Rock Analysis Scanned with High-Resolution X-ray Computed Tomography
This video explains, through animations and real examples, how a step by step geological examination of the earths crust undergoes with X-ray imaging techniques. Researchers use these examinations to decide how and where drillings in the crust must be made.

How X-rays see through your skin – Ge Wang
This video answers the question on how X-rays can see into a person and thereby assist doctors in diagnosing broken bones or tumors.



Et røntgenbillede af en brystkasse
Figure 2: An X-ray image of a chest.
Credit: Mikael Häggström, CC0, via Wikimedia Commons.

Et røntgenbillede af en rygsæk
Figure 3: An X-ray image of a backpack.
Credit: The original uploader was IDuke at English Wikipedia., CC BY 2.5, via Wikimedia Commons.

A large number X-ray images are taken every day all over the world. Imaging techniques are probably the most common X-ray techniques. The images map and show bones, tumors, organs etc. as in figure 2. X-ray imaging techniques can also see into non-biological subjects as seen in airports. In figure 3 one can, with X-rays, see the contents of a backpack containing among other things, batteries, bottles, and a camera.

With simple X-ray imaging techniques, only a flat image can be acquired. Radiologists and scientists can create a 3D-image of their subject by rotating it while the X-ray images are taken. To make it even smarter subjects are scanned in their lengths while they are rotating. This technique is called a CT-scan – which makes cross section images with X-rays. CT-scans have helped the health sector with looking into patients in 3D. The technique can very precisely find the placement, size, and appearance of a tumor.

In figure 4 below we see how a CT-scan can give high resolution imaging of the brain from the top of the skull down to the bottom near the jawbone. The images are taken on a new section every time and the, more than 30, images can together form a 3D image of the brain. Any potential tumors or blood clots can be accurately pinpointed and dealt with.

CT-skanning af kranie
Figure 4: CT-scan of a brain, lower right corner is the start of the scan from the top of the cranium. Top left corner is the end of the scan at the bottom of the cranium near the jawbone.

Bore prøver fra undergrunden
Figure 5: Core drill samples from soil near oil fields to aid in in the examination of faults and cracks in oil field minerals..
Credit: Joshua Doubek, CC BY-SA 3.0, via Wikimedia Commons.

The strength of CT can also be utilized in geology when geologists for example want to drill for crude oil. Geologists use CT to pinpoint where and how they wish to proceed with drilling. CT also makes it possible to be on target with high precision.

In figure 5 above, one can see drill samples from oil fields. These are used to determine faults and cracks in minerals. Geologists can hereafter lay a plan for the most efficient drilling.

X-ray diffraction

Skitse af diffraktion
Figure 6: Sketch of diffraction.
Credit: U. Vainio, Public domain, via Wikimedia Commons.

Eksempel på diffraktion fra enkeltkrystal
Figure 7: Example of diffraction from a single crystal.
Credit: Del45, Public domain, via Wikimedia Commons.

X-ray diffraction is used to find the build and atomic constituents of a crystalline material. And what does that mean? Elements as for example metals prefer to align themselves to an ordered lattice. A lattice in a crystal can reflect-rays when certain conditions are met.

In figure 6 a sketch of diffraction from a large single crystal is seen. In figure 7 an example of a result of a diffraction experiment is shown. Diffraction from different layers of the ordered lattice can interfere with each other and give systematic dots as seen in figure 7.

Figure 8: Chocolate.

Modern chocolate is improved with the help of X-ray diffraction. The cacao in chocolate is crystallized – i.e. it is set in an ordered lattice. Chocolate producers exploit this fact about cacao to tune their recipes. Producers add or remove cacao and sugar to ensure the best crystal in the chocolate – which gives the snap in the chocolate and can determine the shimmer of the chocolate.

Computer chip
Figure 9: Computer chips.

Computer chips are in almost all kind of modern technology the smart phone is for example run by a computer chip. Computer chips are made of a crystalline material, namely the semiconductor, which can open and close for the electricity in the chip. Researchers and chip-producers use X-ray diffraction techniques to determine how to tune semi-conductor technology. The better the crystal the more powerful computers and smartphones we get.

Small angle scattering of neutrons and X-rays
To analyze ordinary crystals with a lattice structure scientists use X-ray diffraction. With unordered systems that are not in a lattice structure scientists cannot use diffraction. Instead scientists use solve this issue with small angle scattering.

Small angle scattering can use neutrons, that are elementary particles found in atoms, as well as light namely X-rays. A particle or light is shot or shone onto a subject in a small angle between 0 and 5 degrees. Some subjects scatter light or particles while other subjects are invisible to the shot. Looking at the biological subject in figure 10, scientists can use small angle scattering to get an idea of the size of the subject, its shape, how its outer surface looks in relation to its inner surface and the general relationship between the volumes and sizes of the respective surfaces.

When scientists use particles like neutrons for small angle scattering on a subject, they usually must know something about the subject’s atoms. Neutrons usually have the advantage of being most sensitive to atomic nuclei or their magnetic properties.

Biologiske prøver
Figure 10: Biological samples eligible for small angle scattering experiments.
Credit: LadyofHats, Public domain, via Wikimedia Commons


Quantum Mechanics and Neutron Scattering 1/2

Quantum Mechanics and Neutron Scattering 2/2

Small Angle Neutron Scattering by the Monstars

Small angle scattering demonstration using hairs in laserlight! Part 1

Small angle scattering demonstration using hairs in laserlight! Part 2