The Zn Vacancy-Mediated De-Accumulation Based Process for Hydrogen Production Performance Promotion of 1D Zn─Cd─S Nanorods.

Due to their anisotropy, 1D semiconductor nanorod-based materials have attracted much attention in the process of hydrogen production by solar energy. Nevertheless, the rational design of 1D heterojunction materials and the modulation of photo-generated electron-hole transfer paths remain a challenge. Herein, a ZnCdS@ZnS/MoS core-shell nanorod heterojunction is precisely constructed via in situ growth of discontinuous ZnS shell and MoS NCs on the Zn─Cd─S nanorods.

The dependence of the boson peak on the thickness of CuZr film metallic glasses.

In this study, intensive calculations were performed to investigate the behavior of the low-temperature excess heat capacity of Cu50Zr50 ultrathin film metallic glasses. Our results show that there is a well-defined boson peak in the film metallic glasses and that the boson peak height exhibits an obvious size-dependent feature. Furthermore, there is a critical thickness dc in the curves between the boson peak height and the thickness, where the boson peak height changes abruptly.

A comprehensive study of the red persistent luminescence mechanism of YOS:Eu,Ti,Mg.

YOS:Eu,Ti,Mg, a persistent luminescence (PersL) material that exhibits eye-sensitive red emission for longer than 4-5 h, has attracted much attention and has been intensively researched over the past decade. If it is figured out how to prolong its decay time for longer than 8 h, the amazing candle-like red PersL performance, once lit, can illuminate a room all night without electricity. However, the PersL mechanism is still confusing, since different investigators have their own unique understanding about it based on their personal experimental observations.

Reaction mechanism between small-sized Ce clusters and water molecules II: an ab initio investigation on Ce (n = 1-3) + mHO (m = 2-6).

Possible reactions between the products of the three independent reactions involving a small Ce cluster and a single water molecule, Cen + H2O (n = 1-3), and an additional H2O molecule are systematically investigated. The ground-state isomers of the final products and the reaction pathways involving multiple water molecules are predicted. We find that under either ambient or UV-irradiation conditions, all the reactions can entail low energy barriers.

Structural origin of the high glass-forming ability of CeGaCu alloys.

The CeGaCu amorphous alloy has a good glass-forming ability and many special properties. However, its structure at the atomic scale is unclear. We systematically investigated the structure evolution of Ce70GaxCu30-x (x = 6, 10, 13) glass formation melts by ab initio molecular dynamics (AIMD) simulations.

Reaction mechanism between small-sized Ce clusters and water molecules: an ab initio investigation on Ce + HO.

Reactions of small-sized cerium clusters Cen (n = 1-3) with a single water molecule are systematically investigated theoretically. The ground state structures of the Cen/H2O complex and the reaction pathways between Cen + H2O are predicted. Our results show the size-dependent reactivity of small-sized Ce clusters.

Understanding the quenching nature of Mn in wide band gap inorganic compounds: design principles for Mn phosphors with higher efficiency.

Mn4+ doped phosphors, as an alternative to rare-earth element doped phosphors, have attracted immense attention owing to their ultrahigh quantum efficiency of red emission for potential applications in high rendering white LEDs (light-emitting diodes). Their performance can be largely affected by quenching phenomena such as thermal quenching, concentration quenching and the quenching induced by some intrinsic/extrinsic defects. However, the quenching mechanisms due to the defect levels and host band are still incompletely understood.

Correlation between the electronic structure, topologic structure and dynamic properties of liquid cerium.

In literature, two different kinds of cerium atoms, namely Ce atoms with a localized 4f-electron and an iterant 4f-electron, have been suggested to coexist in low-density liquid cerium (A. Cadien et al., Phys.

Structural, electronic and mechanical properties of sp-hybridized BN phases.

Motivated by the discovery of new phases of carbon under cold high-pressure compression, we performed a global structure search of high-pressure phases of boron nitride (BN). Ten new bulk phases were identified, each energetically more stable than the graphite-like hexagonal BN (h-BN) under high pressures. All ten high-pressure phases could be viewed as involving a stacking of buckled h-BN layers.

Rutile TiO(011)-2 × 1 Reconstructed Surfaces with Optical Absorption over the Visible Light Spectrum.

The stable structures of the reconstructed rutile TiO(011) surface are explored based on an evolutionary method. In addition to the well-known "brookite(001)-like" 2 × 1 reconstruction model, three 2 × 1 reconstruction structures are revealed for the first time, all being more stable in the high Ti-rich condition. Importantly, the predicted TiO-2 × 1 surface model not only is in excellent agreement with the reconstructed metastable surface detected by Tao et al.

New structures of bilayer germanium nanosheets predicted by a particle swarm optimization method.

A global search for the stable structures of bilayer Ge (BLG) is performed, and the most stable and meta-stable BLG structures are predicted for the first time. Phonon-spectrum calculations and ab initio molecular dynamics simulations confirm their dynamical and thermal stability. The computed electronic structures suggest that the most stable structure is metal while the meta-stable structure of BLG is a semiconductor with an indirect band gap (0.

The influence of liquid Pb-Bi on the anti-corrosion behavior of Fe3O4: a first-principles study.

In this work, the influence of Pb and Bi atoms on the anti-corrosion behavior of the oxide film (Fe3O4) formed on steel surface is investigated based on first-principles calculations. Through calculations of the formation energies, we find that Pb and Bi atoms can promote the formation of point defects, such as interstitial atoms and vacancies in Fe3O4. Besides, the effects of the concentration of Pb (or Bi) and pressure on the formation of these defects are also studied.

Persistent Luminescence Hole-Type Materials by Design: Transition-Metal-Doped Carbon Allotrope and Carbides.

Electron traps play a crucial role in a wide variety of compounds of persistent luminescence (PL) materials. However, little attention has been placed on the hole-trap-type PL materials. In this study, a novel hole-dominated persistent luminescence (PL) mechanism is predicted.

Computational analysis of stable hard structures in the Ti-B system.

The lowest energy crystalline structures of various stoichiometric titanium boride (Ti-B) intermetallic compounds are sought based on density functional theory combined with the particle-swarm optimization (PSO) technique. Besides three established experimental structures, i.e.

The search for the most stable structures of silicon-carbon monolayer compounds.

The most stable structures of two-dimensional (2D) silicon-carbon monolayer compounds with different stoichiometric compositions (i.e., Si : C ratio = 2 : 3, 1 : 3 and 1 : 4) are predicted for the first time based on the particle-swarm optimization (PSO) technique combined with density functional theory optimization.

Structural and magnetic evolution of bimetallic MnAu clusters driven by asymmetric atomic migration.

The nanoscale structural, compositional, and magnetic properties are examined for annealed MnAu nanoclusters. The MnAu clusters order into the L1(0) structure, and monotonic size-dependences develop for the composition and lattice parameters, which are well reproduced by our density functional theory calculations. Simultaneously, Mn diffusion forms 5 Å nanoshells on larger clusters inducing significant magnetization in an otherwise antiferromagnetic system.

Efficient electron and hole doping in compositionally abrupt Si/Ge nanowires.

Efficient doping in semiconductor nanowires can be a challenging task in materials science. In this study, we explore effects of various dopant elements (P, N, Al, B, and O) on the electronic properties of three types of compositionally abrupt SiGe nanowires (NWs), namely, the core-shell Ge(core)/Si(shell) and Si(core)/Ge(shell) NWs, and the fused triangular-prism SiGe NW. Based on the density-functional theory calculations, we find that the substitution of Ge by the pentavalent P at the interfacial region between the core and shell of Ge/Si NWs leads to an easy injection of high-density free-electron-like carriers, whereas the substitution of Si by trivalent Al or B at the interfacial region leads to an easy injection of high-density free-hole-like carriers.

Experimental and theoretical studies of hydroxyl-induced magnetism in TiO nanoclusters.

A main challenge in understanding the defect ferromagnetism in dilute magnetic oxides is the direct experimental verification of the presence of a particular kind of defect and distinguishing its magnetic contributions from other defects. The magnetic effect of hydroxyls on TiO nanoclusters has been studied by measuring the evolution of the magnetic moment as a function of moisture exposure time, which increases the hydroxyl concentration. Our combined experiment and density-functional theory (DFT) calculations show that as dissociative water adsorption transforms oxygen vacancies into hydroxyls, the magnetic moment shows a significant increase.

[CTi7(2+)]: Heptacoordinate Carbon Motif?

A heptacoordinate carbon motif [CTi7(2+)] is predicted to be a highly stable structure (with D5h point group symmetry) based on ab initio computation. This motif possesses a sizable HOMO-LUMO gap along with the lowest vibrational frequency greater than 95 cm(-1). An investigation of the motif-containing neutral species [CTi7(2+)][BH4(-)]2 further confirms the chemical stability of the heptacoordinate carbon motif.

Polymorphic phases of sp3-hybridized carbon under cold compression.

It is well established that graphite can be transformed into superhard carbons under cold compression (Mao et al. Science 2003, 302, 425). However, structure of the superhard carbon is yet to be determined experimentally.

Theoretical and experimental characterization of structures of MnAu nanoclusters in the size range of 1-3 nm.

Relative stabilities of MnAu magic-number nanoclusters with 55, 147, 309, and 561 atoms and highly symmetric morphologies (cuboctahedron, icosahedron, onion-like, and core-shell, respectively) are investigated based on density functional theory methods. Through an extensive search, spin arrangements on Mn atoms that give rise to lowest-energy clusters are predicted. The antiferromagnetic spin configurations are found to be the most favorable for all morphologies investigated.