[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

CA : A Cancer Journal for Clinicians

Nitrogen doping has been an effective way to tailor the properties of graphene and render its potential use for various applications. Three common bonding configurations are normally obtained when doping nitrogen into the graphene: pyridinic N, pyrrolic N, and graphitic N. This paper reviews nitrogen-doped graphene, including various synthesis methods to introduce N doping and various characterization techniques for the examination of various N bonding configurations. Potential applications of N-graphene are also reviewed on the basis of experimental and theoretical studies.

https://s3-eu-west-1.amazonaws.com/pfigshare-u-files/1431849/NitrogenReviewonRecentProgressinNitrogenDopedGrapheneSynthesisCharacterizationandItsPotentialApplications.pdf

Review on Recent Progress in Nitrogen-Doped Graphene: Synthesis, Characterization, and Its Potential Applications

日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

The electronic ground state of a periodic system is usually described in terms of extended Bloch orbitals, but an alternative representation in terms of localized "Wannier functions" was introduced by Gregory Wannier in 1937. The connection between the Bloch and Wannier representations is realized by families of transformations in a continuous space of unitary matrices, carrying a large degree of arbitrariness. Since 1997, methods have been developed that allow one to iteratively transform the extended Bloch orbitals of a first-principles calculation into a unique set of maximally localized Wannier functions, accomplishing the solid-state equivalent of constructing localized molecular orbitals, or "Boys orbitals" as previously known from the chemistry literature. These developments are reviewed here, and a survey of the applications of these methods is presented. This latter includes a description of their use in analyzing the nature of chemical bonding, or as a local probe of phenomena related to electric polarization and orbital magnetization. Wannier interpolation schemes are also reviewed, by which quantities computed on a coarse reciprocal-space mesh can be used to interpolate onto much finer meshes at low cost, and applications in which Wannier functions are used as efficient basis functions are discussed. Finally the construction and use of Wannier functions outside the context of electronic-structure theory is presented, for cases that include phonon excitations, photonic crystals, and cold-atom optical lattices.

Maximally-localized Wannier Functions: Theory and Applications

The magnetic phase diagram has been mapped out via the measurements of electronic resistivity, magnetization, and specific heat in the cobalt-based layered $L$Co${}_{1\ensuremath{-}x}$Fe${}_{x}$AsO ($L=\mathrm{La}$, Sm) compounds. The ferromagnetic (FM) transition at $\ensuremath{\sim}$63 K for LaCoAsO is rapidly suppressed upon Fe doping, and ultimately disappears around $x$ $=$ 0.3 in the LaCo${}_{1\ensuremath{-}x}$Fe${}_{x}$AsO system. When La is replaced by magnetic rare-earth element Sm, the $3d$ electrons first undergo a FM transition at ${T}_{c}\ensuremath{\sim}75$ K, followed by an antiferromagnetic (AFM) transition at a lower temperature ${T}_{N1}\ensuremath{\sim}45$ K. With partial Fe doping on the Co site, both FM (${T}_{c}$) and AFM (${T}_{N1}$) transition temperatures are significantly suppressed, and finally approach 0 K at $x=0.3$ and 0.2, respectively. Meanwhile, a third magnetic transition at ${T}_{N2}\ensuremath{\sim}5.6$ K for SmCoAsO, associated with the AFM order of the Sm${}^{3+}$ 4$f$ moments, is uncovered and ${T}_{N2}$ is found to be almost robust against the small Fe doping. These results suggest that the 4$f$ electrons of Sm${}^{3+}$ have an important effect on the magnetic behavior of 3$d$ electrons in the 1111 type Co-based $L$Co${}_{1\ensuremath{-}x}$Fe${}_{x}$AsO systems. In contrast, the magnetism of the $f$ electrons is relatively unaffected by the variation of the 3$d$ electrons. The rich magnetic phase diagram in the Co-rich side of the $L$Co${}_{1\ensuremath{-}x}$Fe${}_{x}$AsO system, therefore, is established.

Magnetic phase diagram in the Co-rich side of the L Co 1 − x Fe x AsO ( L = La, Sm) system

Aluminium film has been electrodeposited onto sintered NdFeB magnet at room temperature (25°C) in ionic liquid electrolytes named aluminium chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Electrodeposition mechanism of Al film is analysed using cyclic voltammetry and chronoamperometry measurements. Structure and morphology of specimen are characterised and analysed using X-ray diffraction, energy-dispersive X-ray spectrum and atomic force microscopy. The results indicate that the process of Al electrodeposition follows the three-dimensional instantaneous nucleation mechanism. As the potentials vary from −0.4 to −0.8 V, the diffusion coefficient (D) of and the calculated number density of Al valid nuclei sites (N0) on the sintered NdFeB magnet both increases. The deposited films consist of pure fcc phase of Al metal, and Al grains with crystal orientation of {111}, {200}, {220} and {311} are dominant components. Al film deposited at −0.6 V has finer and smoother surface, with the r...

Effect of potential on aluminium early-stage electrodeposition onto NdFeB magnet

The temperature evolution of the upper critical field $H_{c2}(T)$ in the noncentrosymmetric superconductor PbTaSe$_2$ was determined via resistivity measurements down to 0.5 K. A pronounced positive curvature in the $H_{c2}$-$T$ phase diagram was observed in the whole temperature range below $T_c$. The Seebeck coefficient $S(T)$ in the temperature range 5K$\leq$$T$$\leq$350K was found to be negative in sign, modest in magnitude and non-linear in temperature. In addition, the superconducting transition temperature $T_c$ under hydrostatic pressure shows a marked non-monotonic variation, decreasing initially with the applied pressure up to $P_c$$\sim$5-10 kbar but then rising with further pressurization. The underlying physical mechanisms of all these findings have been discussed.

Upward curvature of the upper critical field and the V-shaped pressure dependence of $T_c$ in the noncentrosymmetric superconductor PbTaSe$_2$

We present results on the energetics and dynamics of Au atoms interacting with alkanethiol monolayers using molecular dynamics in conjunction with quantum-mechanical calculations. Using a classical force field calibrated by first-principle calculations, we have found that under certain physical conditions, gold atoms can penetrate the molecular monolayer to join the underlying Au(111) surface. We have investigated the dependence of surface coverage and temperature, and have found that our results agree well with available experimental observations. The electronic structure of the system, the potential energy as a function of penetration depth, and the charge transfer at the interface between the molecules and the Au(111) surface are analyzed to determine the potential implications for experiments.

Molecular Dynamics Simulations of Au Penetration through Alkanethiol Monolayers on the Au(111) Surface

Via ab initio simulation, we study the behavior of interfaces of water with silica nanotubes. We find profound differences between zero and finite tensile strains and between unconfined (exterior) versus confined (interior) water. For these distinct cases, we characterize the fracture dynamics of the silica nanotube and the underlying physical mechanisms.

Chao Cao

Papers

Magnetic phase diagram in the Co-rich side of the L Co 1 − x Fe x AsO ( L = La, Sm) system

Effect of potential on aluminium early-stage electrodeposition onto NdFeB magnet

Upward curvature of the upper critical field and the V-shaped pressure dependence of $T_c$ in the noncentrosymmetric superconductor PbTaSe$_2$

Molecular Dynamics Simulations of Au Penetration through Alkanethiol Monolayers on the Au(111) Surface

Predictive first-principles simulations of strain-induced phenomena at water-silica nanotube interfaces.