Influence of dynamic crystallization on exchange-coupled NdFeB nanocrystalline permanent magnets

Dynamic crystallization was introduced to improve the magnetic properties of NdFeB nanocrystalline permanent magnets by optimizing microstructure.The microstructure was studied by X-ray diffraction(XRD)and transmission electron microscopy(TEM).It has been determined that,compared with the conventional heat treatment,dynamic crystallization can shorten the crystallization time.Moreover,dynamic crystallization can refine grains,enhance the exchange-coupled interaction among grains,and promote the magnetic properties.As a result,the optimal magnetic properties of Nd_(10.5)(FeCoZr)_(83.4)B_(6.1)(B_(r)=0.685 T,H_(ci)=732 kA·m^(-1),H_(cb)=429 kA·m^(-1),(BH)_(m)=75 kJ·m^(-3))are obtained after dynamic crystallization heat treatment at 700℃for 10 min.

Static and Dynamic Analysis of Lasing Action from Single and Coupled Photonic Crystal Nanocavity Lasers

The single and coupled photonic crystal nanocavity lasers are fabricated in the InGaAsP material system and their static and dynamic features are compared. The coupled-cavity lasers show a larger lasing e^ciency and generate an output power higher than the single-cavity lasers, results that are consistent with the theoretical results obtained by rate equations. In dynamic regime, the single-cavity lasers produce pulses as short as 113 ps, while the coupled-cavity lasers show a significantly longer lasing duration. These results indicate that the photonic crystal laser is a promising candidate for the light source in high-speed photonic integrated circuit.

A New Chirality Invertible Photoswitch:Light-Driven Axially Chiral Hydrazone Enabling Dynamic Handedness Inversion of Self-Organized Helical Superstructure

Inspired by nature,dynamic self-organized helical superstructures are becoming attractive as building blocks in soft photonic crystals and advanced chiroptical devices.Herein,a chirality invertible hydrazone photoswitch,possessing high helical twisting power(HTP)was judiciously designed and synthesized.Due to the photoinduced configuration changes of the hydrazone photoswitch,it displayed superior thermal stability and strikingly reversible HTP changes.By incorporating a novel chiral hydrazone(CH)into the liquid crystal(LC)host,a handedness invertible cholesteric liquid crystal(CLC)helical superstructure with high thermal stability and light-modulated photonic bandgap was prepared.We inferred that the mechanism of chirality inversion of the novel CH photoswitch derived from changes in the dihedral angle between the two naphthalene rings induced by hydrazone isomerization.Therefore,the influence of chemical structures on its photoresponsiveness was explored.Finally,the potential applications of this advanced light-driven CLC in soft photonic crystals,showing erasable and rewritable colorful patterns and chiroptical templates to induce handedness invertible circularly polarized luminescence were illustrated.

Phonon Dispersion in Equiatomic Li-Based Binary Alloys

The computations of the phonon dispersion curves （PDC） of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom （PAA） is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree （H） and Ichimaru-Utsumi （IU） are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.

A repeated interdiffusion method for efficient planar formamidinium perovskite solar cells

A repeated interdiffusion method is described for phase-stable and high-quality （FA,MA）PbI3 film. The crys- tallization and growth of the perovskite films can be well controlled by adjusting the reactant concentrations. With this method, dense, smooth perovskite films with large crystals have been obtained. Finally, a PCE of 16.5% as well as a steady-state efficiency of 16.3% is achieved in the planar perovskite solar cell.

Research on the nanometric machining of a single crystal nickel via molecular dynamics simulation

Molecular dynamics simulations are employed to study the nanometric machining process of single crystal nickel. Atoms from different machining zones had different atomic crystal structures owing to the differences in the actions of the cutting tool. The stacking fault tetrahedral was formed by a series of dislocation reactions, and it maintained the stable structure after the dislocation reactions. In addition, evidence of crystal transition and recovery was found by analyzing the number variations in different types of atoms in the primary shear zone, amorphous region, and crystalline region. The effects of machining speed on the cutting force, chip and subsurface defects, and temperature of the contact zone between the tool and workpiece were investigated. The results suggest that higher the machining speed, larger is the cutting force. The degree of amorphousness of chip atoms and the depth and extent of subsurface defects increase with the machining speed. The average friction coefficient first decreases and then increases with the machining speed because of the temperature difference between the chip and machining surface.

Pseudorotaxane Ligand-Induced Formation of Copper(I)lodide Cluster Based Assembly Materials:From Zero to Three Dimensional

Comprehensive Summary In this work,we have successfully obtained a series of novel copper(I)–iodide clusters(CuI NCs)based assembly materials by combining supramolecular pseudorotaxane ligands{[Mebpe^(+)]PF_(6)^(–)@CB[6](CB[6]=cucurbit[6]uril),L’·PF_(6)}and linkers{BPHF@CB[6],[BPHF=C_(14)H_(20)N_(4)(PF_(6))_(2)],L·PF_(6)},including discrete cluster CuI 1 and extended cluster organic frameworks MORF 1 and MORF 2.CuI 1 can be described as a dumbbell-shaped molecule with its body-centered site and two vertexes respectively occupied by one[Cu_(5)I_(6)]^(–)cluster and two CB[6]held together by two L’·PF_(6) ligands.The crystal structures of MORF 1 and MORF 2 are 1D anionic chain and four-fold interpenetrated 3D cationic diamondoid structure,respectively,which all featured intriguing alternating CB[6]and CuI NCs.

Molecular-scale processes affecting growth rates of ice at moderate supercooling

The growth kinetics of ice are modeled using the Water Potential from Adaptive Force Matching for Ice and Liquid （WAIL） potential with molecular dynamics. The all-atom WAIL model provides a good description of the properties of both ice and liquid with an equilibrium temperature of 270 K at 1 bar. The growth kinetics captured by this model can thus reflect those of real ice. Our simulation indicates that the growth rate of ice on the basal plane is fastest at approximately 20 K supercooling, consistent with experimental findings, where the growth rate increases monotonically as the supercooling increases to 18 K. The key factors that control the growth kinetics leading to the optimal growth temperature are investigated. The simulation revealed a bilayer-by-bilayer growth mechanism on the basal plane that proceeds in two steps. Whereas water molecules lose translational motion and become ice-like quickly, the establishment of orientational order to form ice is a slow and activated process. Enhanced by the templating effect of sublayers, the rapid reduction in translational motion in the formation of the prefreezing layer might explain the significantly faster growth rate relative to the nucleation rate of water. Whereas remelting of the prefreezing layer is observed at low supercooling and may be responsible for the lower growth rate close to the melting temperature, the slow orientational ordering of the prefreezing layer into the final ice conformation is partly responsible for the reduced growth rate at deeper supercooling.