ASTAR: Automatic Crystal Orientation and Phase Mapping Package for TEM
Click here to view the Editor's interview with Stavros Nicolopoulos at M&M
Electron backscatter(ing) diffraction (EBSD) orientation maps in the SEM have usually poor resolution in comparison with TEM maps showing detailed nanostructure. SEM spatial resolution is generally much lower than TEM. EBSD orientation maps in SEM rely on Kikuchi lines generation from sample surface. EBSD-SEM surface specimen preparation is a very critical and time consuming step to produce well defined Kikuchi lines. Many materials (e.g. many ceramics or heavily deformed metals) do not show any Kikuchi line contrast so EBSD-SEM is not possible. And it is a time consuming technique (e.g. hours typical time for EBSD map).
ASTAR is a new technique for phase/orientation mapping in the TEM. With ASTAR, a sample area is scanned (e.g. a matrix of 500x500 points) at TEM resolution (e.g. 5-nm stepsize for FEG-TEM to 20-nm stepsize for a LaB6 TEM). Scanning is performed by dedicated unit Spinning Star (no STEM needed).
Spot ED patterns are collected from a sample area (a matrix of 500x500 points) with a fast dedicated CCD camera (external or online). All collected spot ED patterns are stored in a dedicated computer for comparison with databank of known crystal phases and orientations. Template generation of all possible simulated orientations(every1º) within the stereographic triangle for existing crystallattice(s) and symmetry.
Cross-correlation comparison of all collected ED patterns with all simulated templates to deduce detailed phase and orientation mapping. Detailed map generation (nm) for all crystal phases and orientations.
ASTAR can easily be retrofitted to any old or new 100-400 kV TEM.
For further information download a brochure here: http://www.nanomegas.com/files/ASTARwebPRESENTATION.pdf.
Contact: NanoMEGAS SPRL, Blvd Edmond Machtens 79, B-1080 , Brussels BELGIUM
Email: info@nanomegas.com nanomegas@gmail.com * Please send your request to both e-mails to ensure a quick reply.
