Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 31: Postersitzung II

MM 31.22: Poster

Mittwoch, 16. März 2011, 17:15–18:45, P5

Towards the study of electric field gradients in M₂AlC (M = Ti, Nb, V, Cr) MAX phases — •Daniel Jürgens¹, Christoph Brüsewitz¹, Michael Uhrmacher¹, Hans Hofsäss¹, and Michel W. Barsoum² — ¹Georg-August-Universität Göttingen, II. Phys. Inst., Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Dep. Mat. Sci. & Eng., Drexel University, Philadelphia, PA 19104, USA

Layered ternary carbides like Ti₂AlC and Nb₂AlC have attracted great attention in recent time. These materials belong to the MAX phase family whose compounds show an unique combination of both metal- and ceramic-like properties. Some features are their excellent thermal and electrical conductivity even at high temperatures, their low density and high oxidation resistance as well as their easy machinability.
The purpose of this work is to describe and understand their physical behavior on atomic scale since many investigations came to the conclusion that the observed characteristics on the mm or even µm scale have their origin in the microstructure. To do so the technique of perturbed angular correlation (PAC) was used beside XRD to gain detailed information about the atomic environment. Radioactive ¹¹¹In ions, decaying by a γ-γ cascade, were implanted into the samples, sensing as spies their local surrounding via hyperfine interactions. This method was applied to Ti₂AlC, Nb₂AlC, V₂AlC and Cr₂AlC. In each material an axially symmetric EFG was found with a characteristic quadrupole coupling constant ν_Q variing between 180 MHz and 260 MHz, which decreases linearly with increasing measurement temperature. This work is supported by the DFG under contract HO 1125/19-1.