Electronic structures and bonding properties of Ti₂AlC and Ti₃AlC₂

Abstract

The relation among electronic structure, chemical bond and property of Ti₂AlC, Ti₃AlC₂ and doping Si into Ti₂AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti₂AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti₃AlC₂, especially in Ti-Al, are stronger than those in Ti₂AlC. Therefore, in synthesis of Ti₂AlC, the addition of Si enhances the Ti₃AlC₂ content instead of Ti₂AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti₂AlC and Ti₃AlC₂. The DOS of Ti₃AlC₂ is much like that of Ti₂AlC. Ti₂Si_xAl_1−xC has more obvious tendency to form a semiconductor than Ti₂AlC, which is seen from the obvious difference of partial DOS between Si and Al 3p.

Keywords

Ti₂AlC / Ti₃SiC₂ / doping / electronic structure / chemical bond

References

[1] Zhimei S., Yanchun Z., Jian Z. The Anomalous Flow Behaviour in the Layered Ti₃SiC₂ Ceramic[J]. Philosophical Magazine Letters, 2000, 80(5): 289-293.

[2] Zhu J. Study on Synthesis and Properties of Ternary Layered Carbide Ti ₃ SiC ₂[D], 2003. Wuhan: Wuhan University of Tecnology.

[3] Min X.-m., Xing X.-l., Mei B. Electronic Structure and Chemical Bond of Ti₃SiC₂ and Adding Al Element[J]. J. Wuhan Uni. Tech.-Mat. Sci. Ed., 2006, 21(2): 221-23.

[4] Ellis D. E., Painter G. S. Discrete Variational Method for the Energy-bond Problem with General Crystal Potential[J]. Phys. Rev., B, 1970, 2: 2 87-2 898.

[5] Xiao S.-X., Wang C.-Y., Chen T.-L. The Method of Density Function and Discrete Variation Used in Chemistry and Material Physics[M], 1998. Beijing: Science Press.

[6] Zhou W. Study on Fraction of Ti ₂ AlC Ceramics[D], 2003. Wuhan: Wuhan University of Tecnology.

[7] Min X.-m., Xiao R.-j., Wang H., Wang W.-min. Electronic Structure and Chemical Bond of Titanium Diboride[J]. J. Wuhan Uni. Tech.-Mat. Sci. Ed., 2003, 18(2): 11-14.

[8] Farber L., Levin I., Barsoum M. W., . High-resolution Transmission Electron Microscopy of some Ti _n+1 AX _b Compounds (n=1,2; A=Al or Al; X=C or N)[J]. J. Applied Phys., 1999, 86(5): 2 540-2 543.

[9] Barsoum M. W., Yoo H. I., Polushina I. K., . Electrical Conductivity, Thermopower, and Hall Effect of Ti₃AlC₂, Ti₄AlN₃, and Ti₃SiC₂[J]. Phys. Re. B, 2000, 62(15): 10 194-10 198.