AR STEM – state of the art atomic resolution scanning transmission electron microscope
The development of new technologies in the areas included in the idea of the sustainable development, like renewable resources, remediation of waste water, low-carbon technologies, etc. are strongly connected with the parallel development of new materials. During the study of modern materials it could be seen that the crystal structure and chemical composition on very small scale, sometimes even on the atomic level, influence strongly the properties. In last decades also fast development of the instruments that enable the study of very small volumes is present. As a top-end of such instruments is the scanning transmission electron microscope with the atomic resolution (AR STEM).
Such a microscope, built in Japan (Jeol, ARM 200 CF) was purchased for the first time in Slovenia as a joint project of National Institute of Chemistry and Centre of Excellence for low-carbon technologies. Instrument is installed in the specially designed and prepared room in the Pregel research centre at the National Institute of Chemistry, Ljubljana, Slovenia.
With this, extremely complex and expensive tool, it is possible to examine solid samples at up to 150 million magnification and observe columns of atoms. From the distribution of the atoms we can determine the crystal structure and using specific spectroscopy methods like energy dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS) we can find the quantity of specific elements. Beside that we can determine the local bonding, coordination and valence state of the atoms. Using all these data we ca practically completely describe the structure of nanoparticles, crystal boundaries, two dimensional defects, etc. Using tomography, where we take images at different tilting angles we can reconstruct the 3D shape of the particles or macromolecules.
The instrument will be very important tool for different projects and also for direct analysis of the materials and products from Slovenian industry. With detailed analysis and knowledge of microstructure evolution during the fabrication we will be able to improve the properties and to create better conditions for marketing of the products.
EFTEM (energy filetered TEM) image of catalyst based on Cu3Pt embeded in carbon matrix. Carbon – green, platinum – cyan and copper – blue.
HAADF/STEM (high-angle annular dark-field scanning transmission electron microscopy) image of copper (darker contras) and platinum (brighter) atoms in 20nm sized nanoparticle of catalyst based on Cu3Pt compound. On the outer side of the particle Pt rich »skin« layer could be observed.
HAADF/STEM image at atomic resolution
Coherent boundary between two phases in the (K,Na)NbO3 system. Nb atoms (brighter contrast) occupy B perovskite sites while K and Na are on the A sites (darker contrast)
|EQUIPMENT||MultiMode V Scanning Probe Microscope (Veeco Instruments Inc.)|
|Year of purchase||2008|
|Access to equipment||Access to the machine is limited to partners, which claim a share. These are employes of different laboratories of NIC, Faculty of chemistry and chemical technology, Faculty of pharmacy and Faculty of mechanical engineering MB.|
|Purpose of equipment and additional information||Characterisation of different materials at the molecular level. Possiblity of in situ measurements and use to analyse biological systems in their living environment.|
|Price for use of equipment (EUR/h)||12,71|