Nano-Crystalline and High-Temperature Ceramics
Ceramics are the industrial material of choice when it comes to severe conditions such as high temperatures and steep thermal gradients in melting furnaces, rapid thermal cycling in reactors or chemical corrosion in filter beds. While only a fairly small group of chemical compounds are sufficiently resilient to withstand such conditions, the physical make-up of the material plays an important role in providing strength. Granular ceramics also play an important role as sensors of industrial process parameters such as temperature, pressure or reactant concentration. Again, the physical microstructure, i.e. the size, shape and arrangement of the grains in the granular ceramic determine the behaviour of the material.
In the Materials Physics group, a combination of experimental techniques are applied to study the structure and its response to severe thermal and chemical conditions on all length scales from the atomic level to individual grains to macroscopic specimens. The atomic structure is determined by Nuclear Magnetic Resonance (NMR), a technique in which the electron density of the material under study is determined by subjecting the sample to radio-frequency magnetic fields. The structure of crystalline components and the strain caused in them by thermal effects are probed by X-Ray Diffraction (XRD), and the three-dimensional arrangement of both granular and continuous phases in a granular ceramic is investigated by Small-Angle X-ray Scattering (SAXS), a synchrotron-based experiment which exploits the fact that interfaces between components with different index of refraction scatter light (including x-rays) at an angle determined by the curvature of the interface.
With all three techniques, NMR, XRD and SAXS, we aim to conduct experiments under controlled in-situ conditions, i.e. with well-characterised thermal gradients and chemical conditions. This requires the design and construction of sample cells for dedicated experiments. Currently, we operate a laser-heated NMR probe, and a laser-heated diffraction cell with integrated pyro-microscope is currently being planned.