Particle formation

Chemistry is the science of the transformation of matter.

When making batch syntheses the final product is analyzed where after some parameters, such as temperature, synthesis time, pH, concentration etc. are changed in order observe how it affects the final product. It is possible to investigate how particle forms and growth as a function of time by doing an in situ study which is often done at synchrotron facilities.

With new synchrotron instrumentation and time resolution, the complexity of the reactions that can be studied will be improved. In-situ Powder X-Ray Diffraction (PXRD) has for the past decade been used extensively for studies of crystal-lization and solid state transformations and recently we introduced for the first time in-situ supercritical fluid reactors, which allow studies at high pressure and high temperature.

Supercritical fluid processes are ideal for synthesis of nanoparticles on a time scale of seconds rather than hours. This new field will provide novel insights about nanoparticle growth, formation and structure.

This is possible by monitoring the reaction with scattering measurements employing hard X-rays or neutrons. By measuring both Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS) information on particle size and aggregation can be obtained (from SAXS) at the same time as information on crystallite size, crystallinity and phase transformations (from WAXS)

A diffractiogram showing how CeZrO particles are formed as function of time.

Do you want to read more about crystallography and how we use it in Danish? The paper Se nanomarterialer blive til - in situ krystallografi was published in Aktuel Naturvidenskab in 2015. Read it here.

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