Kaixiao Zhang

STRUCTURAL, ELECTRONIC, MAGNETIC, AND OPTICAL PROPERTIES OF 3d TRANSITION METAL ENDOHEDRAL M@Ge12H12(M=Sc–Ni) CLUSTERS

The fulerine-Ni@Ge12H12 structure, which composes of four pentagons and four rhombi and is like a fullerene, has a closed-shell electronic structure, the largest HOMO–LUMO energy gap, the highest vertical ionization potential, and the lowest vertical electron affinity. All of these properties are characteristic of a magic cluster, therefore, we strongly suggest fulerine-Ni@Ge12H12 should be a magic cluster and promising as building blocks in developing cluster-assembled nanomaterials. This can be interpreted by the weak interaction between Ni and the cage together with the transference of two electrons from the 4s orbital to the 3d orbital of Ni. The magnetic moment of fulerine-M@Ge12H12(M=Sc–Ni) varies from 0 to 3 μB, implying they have potential applications in developing new nanomaterials with tunable magnetic properties. The calculated TDDFT optical properties of fulerine-M@Ge12H12(M=Sc–Ni) can be tuned broadly in the ultraviolet–visible region. This is very important for optoelectronic applications.

High-Performance Flexible In-Plane Micro-Supercapacitors Based on Vertically-Aligned CuSe@Ni(OH)2 Hybrid Nanosheet Films

The orientation and hybridization of ultrathin two-dimensional (2D) nanostructures on interdigital electrodes is vital for developing high-performance flexible in-plane micro-supercapacitors (MSCs). Despite great progress has been achieved, integrating CuSe and Ni(OH)2 nanosheets to generate advanced nanohybrids with oriented arrangement of each component and formation of porous frameworks remains a challenge, and their application for in-plane MSCs has not been explored. Herein, the vertically aligned CuSe@Ni(OH)2 hybrid nanosheet films with hierarchical open channels are skillfully deposited on Au interdigital electrodes/polyethylene terephthalate substrate via a template-free sequential electrodeposition approach, and directly employed to construct in-plane MSCs by choosing polyvinyl alcohol-LiCl gel as both the separator and the solid electrolyte. Because of the unique geometrical structure and combination of intrinsically conductive CuSe and battery-type Ni(OH)2 components, such hybrid nanosheet films can not only resolve the poor conductivity and re-stacking problems of Ni(OH)2 nanosheets but also create the 3D electrons or ions transport pathway. Thus, the in-plane MSCs device fabricated by such hybrid nanosheet films exhibits high volumetric specific capacitance (38.9 F cm-3). Moreover, its maximal energy and power density can reach 5.4 mW h cm-3 and 833.2 mW cm-3, superior to pure CuSe nanosheets, and most of reported carbon materials and metal hydroxides/oxides/sulfides based in-plane MSCs ones. Also, the hybrid nanosheet films device shows excellent cycling performance, good flexibility, and mechanical stability. This work may shed some light on optimizing 2D electrode materials and promote the development of flexible in-plane MSCs or other energy storage systems.

Research of Novel Circular Grating

Given that most of the optical systems are circularly symmetric, the Circular Dammann grating has wide application. However, its parameters’ design is a hard problem which restricts its development. This paper presents a new method to optimize the design of Circular Dammann grating with introducing quantum genetic algorithm and some appropriate revises. Compared with other design methods, it has obvious advantages. At the end of this paper, the simulation results are given.

The simulation of growth thermodynamics in the synthesis of GaN1-xPx alloys

In this paper, thermodynamics method was used to calculate the growth of GaN1-xPx ternary alloys on (0001) GaN/sapphire substrates and the solubility of phosphorus in GaN by using the Gibbs free energy theory was calculated. The calculated results show that great deviation from linearity between the input mole ratio R and the equilibrium partial pressures, and the content of P in GaN varies with the growth temperature and the boundary of the spinodal isotherm shifts from x=0.06 to x=0.25 at the growth temperature of 1200K as the strain factor increases from 0 to 1, indicating that the strain in the GaN1-xPx layers can suppress the phase separation. Meanwhile, with the increase of the effective elastic parameters of GaN and GaP, the available maximum P content also increases slightly at the growth temperature.

The effects of passivation and temperature on the strain of Al0.22Ga0.78N /GaN heterostructuers

The temperature dependencies of c-axis strain in Al0.22Ga0.78N/GaN heterostructure, with and without Si3N4 passivation layer, were investigated at temperatures from room temperature (300K) to 813K using high resolution X-ray diffraction (HRXRD). The unpassivated Al0.22Ga0.78N layers total strain decrease is about 6% and 8% for the 50-nm- and 100-nm-thick Al0.22Ga0.78N layers, respectively, at whole temperature range from 300K to 813K in our measurements. The passivated Al0.22Ga0.78N layers total strain decrease is about 12% and 0% for the 50-nm- and 100-nm-thick Al0.22Ga0.78N layers, respectively, at the whole temperature range in our measurements. And at the common devices working temperature range, after passivating, the strain increase is about 4% and 8% of the 50-nm-thick Al0.22Ga0.78N and 100-nm-thick layers with temperature from 300K to 400K and 300K to 420K, respectively. The results indicate that a reasonable passivation layer is necessary to effectively impede strain decrease of AlxGa1-xN/GaN interface at the higher temperatures and that a passivation layer is conduce to increase c-axis strain at the working temperature range, hence passivation may improve the thermal stability and electricity characteristics of AlxGa1-xN/GaN heterostructures.