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In this research, using the Win2k software based on the Cohen–Sham equations and applying the density functional theory with the help of the full potential linearized augmented plane wave method (FP-LAPW), the dynamic, electronic, optical and thermoelectric parameters of the C₅N monolayer have been physically investigated. The results of electronic properties calculations indicate that the C₅N monolayer has metallic and nonmagnetic properties. The maximum absorption of higher energies occurs at the energy of 11.98eV in the $x$ direction. In the $x$ direction, the peaks are evident in the range of the visible light region at energies of 1eV and 3eV while no peak is observed in the visible light region in the $z$ direction. In addition, the phonon dispersion diagram is calculated by the linear response approach along the symmetric points for this structure. The outcomes provide no negative modes in the phonon spectrum, expressing that these structures are dynamically in equilibrium. The use of Boltzmann transfer theory with the relaxation time approximation to investigate the thermoelectric properties of the C₅N monolayer reveals that the low Seebeck coefficient and the increase of thermal conductivity by increasing temperature leads to a very small ZT for the above monolayer. The minimum value of the Seebeck coefficient at the temperature of 300K is −45$\mu$V/K, and with increasing temperature, it exhibits an upward trend to reach −17$\mu$V/K under a temperature of 600K, meaning that the low value of the Seebeck coefficient (less than 100$\mu$V/K) is in agreement with the metallic nature of this monolayer. The metallic property of this structure is considered an important feature in fabricating electrodes (batteries).

A brief review is given on electronic and transport properties of carbon nanotubes mainly from a theoretical point of view. The topics include a description of electronic states in a tight-binding model and in an effective-mass or k · p scheme. Transport properties are discussed including absence of backward scattering except for scatterers with a potential range smaller than the lattice constant, its extension to multi-bands cases, and long-wavelength phonons and electron-phonon scattering.

We use the Kubo model to calculate the lattice contribution to the thermal conductivity (κ_ph) in MgB₂ superconductors. The theory is formulated when heat transfer is limited by the scattering of phonons from defects, grain boundaries, charge carriers, and phonons. The lattice thermal conductivity in normal state of MgB₂ superconductors dominates and is an artifact of strong phonon-impurity and -phonon scattering mechanism. Later on, the electronic contribution to the thermal conductivity (κ_e) is calculated within relaxation time approximation for π and σ band carriers with s wave symmetry. Such an estimate sets an upper bound on κ_e and is about 30% of the total heat transfer at room temperature. The validity of the Wiedemann Franz law is also examined and an enhanced Lorenz number is obtained. Both these channels for heat transfer are clubbed and κ_tot develops a broad peak at about 120 K, before falling off at higher temperatures weakly. The anomalies reported are well-accounted in terms of the scattering mechanism by phonon and electron with impurities. It is shown that the behavior of the thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between electron and lattice contributions. The contribution of carriers toward κ is substantial and is due to the fact that the carriers are condensed and do not carry entropy. We include comparisons with other theoretical calculations on κ_e and available experimental data. The numerical analysis of heat transfer in the metallic phase of MgB₂ shows similar results as those revealed from experiments.

The thermoelectric properties of LaCo_1-xCu_xO_3-δ ceramics are theoretically analyzed, it is observed that thermoelectric figure of merit ZT ( = S²σT/κ) is maximized by Cu substitution in LaCo_1-xCu_x O_3-δ at x = 0.15. The lattice thermal conductivity (κ_ph) and phonon drag thermoelectric power were estimated by the scattering of phonons with defects, grain boundaries, electrons and phonon umklapp scattering to evaluate the thermoelectric figure of merit ZT. The Mott expression is used to estimate the electron diffusive thermoelectric power using Fermi energy as electron free parameter, shows linear temperature dependence. The electron contribution to thermal conductivity (κ_e) is estimated using temperature-dependent electron relaxation time. We found that Cu substitution increases the phonon scattering with grain boundaries and defects which significantly decrease the thermal conductivity and subsequently increase the thermoelectric power. The present numerical analysis of thermoelectric properties will help in designing more efficient thermoelectric materials for thermoelectric applications.

This paper presents a review on our recent work on carbon nanotube field effect transistors, including the development of ohmic contacts, high-κ gate dielectric integration, chemical functionalization for conformal dielectric deposition and pushing the performance limit of nanotube FETs by channel length scaling. Due to the importance of high current operations of electronic devices, we also review the high field electrical transport properties of nanotubes on substrates and in freely suspended forms. Owing to their unique properties originating from their crystalline 1D structure and the strong covalent carbon–carbon bonding configuration, carbon nanotubes are highly promising as building blocks for future electronics. They are found to perform favorably in terms of ON-state current density as compared to the existing silicon technology, owing to their superb electron transport properties and compatibility with high-κ gate dielectrics. Future directions and challenges for carbon nanotube-based electronics are also discussed.

A brief review is given on electronic and transport properties of carbon nanotubes mainly from a theoretical point of view. The topics include a description of electronic states in a tight-binding model and in an effective-mass or k · p scheme. Transport properties are discussed including absence of backward scattering except for scatterers with a potential range smaller than the lattice constant, its extension to multi-bands cases, and long-wavelength phonons and electron-phonon scattering.