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Surface Effect on Electronic, Magnetic and Optical Properties of PtCoBi Half-Heusler: A DFT Study

Rezazadeh Hamed, Hantehzadeh Mohamadreza, Boochani Arash

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

155--166

EN

The electronic, magnetic, and optical properties of PtCoBi half-Heusler compound [001] surfaces and its bulk state have been investigated in the framework of density functional theory using GGA approximation. The half-metallic behaviors of CoBiterm, CoPt-term and PtBi-term decrease with respect to its bulk state. The spin polarization at the Fermi level is 73.2% for the bulk state, and it is -64.4% and -64.1% for the CoBi-term and PtBi-term, respectively while less polarization has been observed for the CoPt-term. All terminations have given almost similar optical responses to light. Plasmon oscillations for the terminations occur in the range of 12.5 to 14.5 eV (21 to 22 eV) along xx (zz), and it occurs at 23 eV for the bulk state. The refractive index for the bulk and all three terminations is very high in the infrared and visible areas, meaning a very strong metallic trend in these compounds. The phenomenon of super-luminance occurs for the incident light with energy exceeding 5.5 eV for all three terminations, and it occurs in the range of 10 eV for the bulk mode. These terminations show transparent behavior after the energy of 10 eV.

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Enhancement of Thermoelectric Efficiency and Optical Properties of Hydrogen Absorption in SiC:Mn Nanotube

Shahraki Amir Toofani, Gol Heydar Ali Shafiei, Kimiagar Salimeh, Dehnavi Naser Zare

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 2

397--403

EN

The effects of hydrogen absorption and manganese substitution on structural, electronic, optical, and thermoelectric properties of silicon-carbon nanotubes (SiCNT) are studied using the density functional theory and the GGA approximation. An examination of the PDOS curves and the electronic band structure showed that the Mn substitution leads to an increase in magnetic anisotropy and the occurrence of semi-metallic behavior and that the hydrogen absorption shifts the band gap toward the lower energies. A study of these nanostructures’ thermoelectric behavior reveals that the H absorption leads to a significant escalation in the figure of merit of the SiCNT to about 1.6 in the room temperature range. The effects of the H absorption on this nanotube’s optical properties, including the dielectric functions and its absorption spectra, are also investigated.

3

Theoretical studies on the structural, electronic and optical properties of BeZnO alloys

Xiong D. P., Zhou S. L., He M., Wang Q., Zhang W., Feng Z. Y.

Materials Science Poland

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2020

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Vol. 38, No. 4

629--636

EN

The structural, electronic and optical properties of BexZn1−xO alloys were studied using the density functional theory and Hubbard-U method. Uo,p = 10.2 eV for O 2p and UZn,d = 1.4 eV for Zn 3d were adopted as the Hubbard U values. For BexZn1−xO alloys, the lattice constants a and c decrease linearly as Be concentration increases, the bandgap increases with a large bowing parameter of 6.95 eV, the formation enthalpies have the maximum value with Be concentration at 0.625, corresponding to the possible Be concentration to form phase separation. These calculations comply well with the experimental and other theoretical results. Furthermore, optical properties, such as dielectric function ∈(ω), reflectivity R(ω), absorption coefficient α(ω), were calculated and discussed for BexZn1−xO alloys with the incident photon energy ranging from 0 eV to 30 eV.