Journal article
Dielectric properties of Ti2AlC and Ti2AlN MAX phases: The conductivity anisotropy
Journal of applied physics, v 104(2), p23531
15 Jul 2008
Abstract
The optical properties of Ti2AlN and Ti2AlC were determined in the 2-80 eV energy range by electron energy loss spectroscopy and in the visible-ultraviolet range, from 1.6 to 5.5 eV, by spectroscopic ellipsometry. Both experimental techniques are angular resolved and in very good agreement over their overlapping energy range. We observe a dependence of the dielectric function as a function of the crystallographic orientation of the crystals. In particular, we notice a shift of the energy position of the plasmon absorption of Ti2AlC with respect to Ti2AlN. Moreover, a drastic change is also observed in the shape of the dielectric function as a function of the composition (or valence electron concentration). The dielectric functions are fitted to an empirical semiclassic Drude-Lorentz model to obtain physical parameters such as the relaxation times. These microscopic parameters are then used in a macroscopic model to yield the transport properties such as the static conductivity as function of the crystal orientation. Ti2AlN is found to be a better conductor than Ti2AlC in all orientations, which is consistent with experimental measurements. A comparison of the electrical and optical properties of these two compounds is made in terms of different electronic properties and interband-intraband transitions deduced from our model. (C) 2008 American Institute of Physics.
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Details
- Title
- Dielectric properties of Ti2AlC and Ti2AlN MAX phases: The conductivity anisotropy
- Creators
- Noel Haddad - ONERA CNRS, LEM, F-92322 Chatillon, FranceEnric Garcia-Caurel - Ecole Polytech, CNRS, LPICM, UMR 7647, F-91128 Palaiseau, FranceLars Hultman - Linkoping Univ, Dept Phys, IFM, Thin Films Phys Div, S-58183 Linkoping, SwedenMichel W. Barsoum - Drexel UniversityGilles Hug - ONERA CNRS, LEM, F-92322 Chatillon, France
- Publication Details
- Journal of applied physics, v 104(2), p23531
- Publisher
- American Institute of Physics
- Number of pages
- 10
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Materials Science and Engineering
- Web of Science ID
- WOS:000258174800045
- Scopus ID
- 2-s2.0-48849106436
- Other Identifier
- 991019167782704721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Physics, Applied