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Electronic Structure And Optical Properties Of Layered Ternary Carbide From First Principles

Posted on:2012-08-09Degree:MasterType:Thesis
Country:ChinaCandidate:S JinFull Text:PDF
GTID:2210330368977635Subject:Condensed matter physics
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The electronic structure and optical properties of the layered ternary compound Ti3AlC2, Ti3GeC2 and Si doping on Ti3GeC2 have been studied by the first principles method based on density function theory. The principles of electronic structure and optical properties of Ti3AlC2 and Ti3GeC2 have been clarified. Moreover, the mechanism of the optical properties has been researched on the basis of the electronic structure. Furthermore, the effect of Si doping on the electronic structure and optical properties of Ti3GeC2 and its mechanism have also been invesigated.The band structure and density of states (DOS) of Ti3AlC2 and Ti3GeC2 have been calculated respectively. The calculated results show that Ti3AlC2 and Ti3GeC2 are electronic conductors, which is consistent with the experimental result. The partial DOS of Ti3AlC2 and Ti3GeC2 have been studied. In addition, the contribution of all the atomic electrons for the DOS has been analyzed as well. The optical properties of Ti3AlC2 and Ti3GeC2 have been calculated. It is found that the dielectric peak is associated with the transitions from Ti p and d states to Al/Ge s and p states. Moreover, the photoconductivity of Ti3AlC2 exhibits two peaks at 2.7 eV and 34.9 eV, respectively. Its energy loss peak at 36.4 eV is due to the electronic transition from Ti p to Ti d states. There are two peaks at 2.6 eV and 34 eV in photoconductivity of Ti3GeC2. The loss function of Ti3GeC2 exhibits two peaks at 5.5 eV and 36 eV, respectively. With respect to Ti3AlC2 and Ti3GeC2, the calculated results show that their reflectivity in the ultraviolet region is high, indicating that they can be promising candidates for anti-Ultraviolet Rays coating material. The reflectivity of Ti3AlC2 and Ti3GeC2 are nonselective in the visible region, indicating that they can be potential materials for temperature control of space vehicles.The electronic structure and optical properties of Si doping on Ti3GeC2 have been studied. The results show that Ti3Si0.5Ge0.5C2 is anisotropic metals. In addition, it is observed that the DOS at the Fermi level is smaller than that of Ti3GeC2, demonstrating that the metal of Ti3Si0.5Ge0.5C2 is weaker. Furthermore, the optical property of Ti3Si0.5Ge0.5C2 has been calculated. The results show that there are two dielectric peaks at 2.23eV and 35.07eV, respectively. In particular, the peak at 2.23 eV is 50% of the corresponding peak in Ti3GeC2. The reflectivity spectrum of Ti3Si0.5Ge0.5C2 in the visible region also is nonselective, implying that it can be potential material for temperature control of space vehicles. In addition, owing to Si doping, the peak of reflectance of Ti3Si0.5Ge0.5C2 in the ultraviolet region decreases, and the wavelength of peak shifts to shortwavelength.
Keywords/Search Tags:Ti3AlC2, Ti3GeC2, first principles, electronic structure, optical properties
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