A High‐Temperature Neutron Diffraction and First‐Principles Study of Ti 3 AlC 2 and Ti 3( Al 0.8 Sn 0.2) C 2. Issue 2 (16th December 2013)

• Record Type: Journal Article
• Authors: Lane, Nina J.; Vogel, Sven C.; Caspi, El'ad N.; Dubois, Sylvain; Gauthier‐Brunet, Véronique; Bei, Guo Ping; Barsoum, Michel W.; Zhou, Y.
• Is Part Of: Journal of the American Ceramic Society. Volume 97:Issue 2(2014)
• Page Start: 570
• Page End: 576
• Publication Date: 2013-12-16
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.12696
• Languages: English
• ISSNs: 0002-7820

Abstract

<abstract abstract-type="main" id="jace12696-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Herein, we report on the temperature‐dependent crystal structures of Ti <sub>3</sub> AlC <sub>2</sub> and Ti <sub>3</sub> Al <sub>0.8</sub> Sn <sub>0.2</sub> C <sub>2</sub> in the 373–1273 K temperature range, as determined by Rietveld analysis of high‐temperature neutron diffraction time‐of‐flight data. The compositions are 86(1) wt% Ti <sub>3</sub> AlC <sub>2</sub> and 14(1) wt% TiC <sub>0.92(2)</sub> for the sample with no Sn, and 95(1) wt% Ti <sub>3</sub>( Al <sub>0.8</sub> Sn <sub>0.2</sub>) C <sub>2</sub> and 5(1) wt% Ti <sub>2</sub> AlC for the solid solution with Sn . The average linear volumetric thermal expansion is 8.0(2) × 10<sup>−6</sup> K<sup><italic>−</italic>1</sup> for Ti <sub>3</sub> AlC <sub>2</sub> and 8.2(5) × 10<sup>−6</sup> K<sup>−1</sup> for Ti <sub>3</sub>( Al <sub>0.8</sub> Sn <sub>0.2</sub>) C <sub>2</sub>. The average linear thermal expansion in the <italic>a</italic> and <italic>c</italic> directions, respectively, are 7.6(2) × 10<sup>−6</sup> K<sup>−1</sup> and 8.9(2) × 10<sup>−6</sup> K<sup>−1</sup> for Ti <sub>3</sub> AlC <sub>2</sub>. For Ti <sub>3</sub>( Al <sub>0.8</sub> Sn <sub>0.2</sub>) C <sub>2</sub>, the respective values are 8.0(5) × 10<sup>−6</sup> K<sup>−1</sup> and 8.6(6) × 10<sup>−6</sup> K<sup>−1</sup>. In the case of the solid solution, the quadratic thermal expansion coefficients are also given. Detailed bond lengths analysis shows that the thermal expansions along the <italic>a</italic> and <italic>c</italic> directions are controlled by the thermal expansions of the Ti – C, and Ti – Al bond lengths, respectively. The atomic displacement parameters (ADPs) show that the Al and Sn atoms vibrate with a higher amplitude than the Ti and C atoms. Consistent with first‐principles calculations, the ADPs of the Al/Sn site(s) in Ti <sub>3</sub>( Al <sub>0.8</sub> Sn <sub>0.2</sub>) C<sub>2</sub> are lower than the ADPs of Al in Ti <sub>3</sub> AlC <sub>2</sub>.</p> </abstract>