A High‐Temperature Neutron Diffraction and First‐Principles Study of Ti3AlC2 and Ti3(Al0.8Sn0.2)C2
Abstract
Herein, we report on the temperature‐dependent crystal structures of Ti 3 AlC 2 and Ti 3 Al 0.8 Sn 0.2 C 2 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 3 AlC 2 and 14(1) wt% TiC 0.92(2) for the sample with no Sn , and 95(1) wt% Ti 3( Al 0.8 Sn 0.2) C 2 and 5(1) wt% Ti 2 AlC for the solid solution with Sn . The average linear volumetric thermal expansion is 8.0(2) × 10−6 K −1 for Ti 3 AlC 2 and 8.2(5) × 10−6 K−1 for Ti 3( Al 0.8 Sn 0.2) C 2. The average linear thermal expansion in the a and c directions, respectively, are 7.6(2) × 10−6 K−1 and 8.9(2) × 10−6 K−1 for Ti 3 AlC 2. For Ti 3( Al 0.8 Sn 0.2) C 2, the respective values are 8.0(5) × 10−6 K−1 and 8.6(6) × 10−6 K−1. 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 a and c 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 3( Al 0.8 Sn 0.2) C2 are lower than the ADPs of Al in Ti 3 AlC 2.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 16, 2013
- Source ID
- 10.1111/jace.12696
Entities
People
- El’ad N. Caspi
- Guo Ping Bei
- Michel Barsoum
- Nina J. Lane
- Sven C. Vogel
- Sylvain Dubois
- Véronique Gauthier‐brunet
Organizations
- Army Research Office
- Center for Nanoscale Materials
- Drexel University
- Los Alamos Neutron Science Center
- United States Department of Energy