Comparison of structural and photoluminescence properties of ZnO thin films grown by pulsed laser deposition and ultrasonic spray pyrolysis

ZnO thin films have been deposited by pulsed laser deposition (PLD) and ultrasonic spray pyrolysis (USP) method, respectively. X-ray diffraction and transmission electron microscopy characterizations indicate that ZnO film grown by PLD exhibits better crystallinity than that grown by USP. Photoluminescence spectra show that the near-band edge ultraviolet emission of film grown by PLD is narrower and shifts to higher energy, compared with that of film grown by USP. In the visible range, ZnO film grown by PLD exhibits four local level emission centered at 470 nm, 486 nm, 544 nm, and 613 nm, respectively, while the film grown by USP only presents a weak broad band emission centered at 502 nm. Hall measurement shows higher carrier density and lower hall mobility in ZnO film grown by PLD than that in film grown by USP. The higher density of intrinsic defects as well as higher crystallintiy is considered to account for the difference of photoluminescence in ZnO film grown by PLD with that in film grown by USP.     

Low-temperature synthesis of nanocrystalline ZnGa2O4:Tb phosphors via the Pechini method

The synthesis of trivalent terbium doped ZnGa₂O₄ nanosized new phosphors by the Pechini method was reported. Well-crystallized ZnGa₂O₄:Tb³⁺ phosphors were obtained at low-temperature about 550 °C. The phosphors formed porous agglomerates which consist of spherical nanocrystallites with a uniform size at about 30 nm. The photoluminescence of the phosphors included both the luminescence of ZnGa₂O₄ host and characteristic emission of Tb³⁺, and the excitation spectra showed an energy transfer from the host lattice to the activator. The Tb³⁺ emission from the phosphors prepared by the Pechini process was more intensive than that of phosphors by solid-state reaction process.     

Structural approach to nanoscience: a case study of complex and cluster formation in ZnBr2–ZnCl2 melts

Although the melt structure of glass-forming ZnCl₂ has so far been well studied, there exists quite little information on the structural change due to anion-substitution. In the present work, the short-range structure of ZnCl₂–ZnBr₂ mixture melts was analyzed systematically by time-of-flight pulsed neutron diffraction techniques, Raman spectroscopy, molecular orbital calculations, and molecular dynamics simulations. According to radial distribution analysis, it was found that there were tetrahedral structural units of ligand-substituted [ZnCl_nBr_4−n]²⁻ (n=0–4) in these melts, not implying the simple mixing of [ZnCl₄]²⁻ and [ZnBr₄]²⁻ units. Further detailed estimation indicated that the ligand-substituted complex anions were linked with each other by sharing a common anion.     

Editor's Introduction

This paper reviews the state of the art in processing and extraction of ocean floor manganese nodules. It briefly reviews the mining sites where the abundant rich nodules occur and also discusses the metal distribution in nodules in view of economical processing and extraction of these metal values.

The paper discloses in a detailed manner the physical and chemical characteristics of nodules, including porosity, surface area, water content and the effect of temperature on crystal structure of major constituents of nodules.

In the extraction aspect of nodules, the paper reviews two different extraction schemes revealed in the literature, namely hydrometallurgical treatment and pyrometallurgical treatment. The hydrometallurgical treatments include acid leaching, ammonia leaching, leaching with reducing agents and leaching after high temperature pre-treatments such as in sulfating rousting, while the pyrometallurgical processes include smelting, chlorination-vaporization and segregation. The paper also covers metal recovery processes from leach liquor.

An economic survey of processing nodules has been made in terms of problems associated with metal-marketing, and impact of metal production from nodules on mineral industries.     

梅山高炉瓦斯泥综合利用的研究

分析研究国内外高炉粉尘使用情况，结合梅山高炉瓦斯泥的性质、特征和现状，提出用弱磁-强磁选的选矿方法，从梅山高炉瓦斯泥中回收铁精矿的设想。通过试验室试验，取得了较好的技术经济指标，达到了预期效果，并可降低锌含量。     

低品位氧化锌粉矿制粒及碱性浸出

小于2 mm的氧化锌矿(含锌5.17%)与5%的水泥混合,制粒并固化,所得颗粒直径5~8 mm。固化3天、10天、45天的颗粒用碱性溶液浸出,最大浸出率分别为92.2%、87.3%、72.9%。减少固化时间能够缩短反应时间、增加颗粒中锌的溶解以及减少浸出剂中初始锌浓度的影响。实验表明颗粒最少需固化3天。动力学研究表明浸出过程受浸出剂通过脉石层的扩散控制,表观速率常数分别为3.51×10-2d-1、8.09×10-3d-1和4.74×10-3d-1。     

Atomic layer deposition of thin films of ZnSe—structural and optical characterization

Thin films of sphalerite-type ZnSe were grown by atomic layer deposition (ALD) from elemental Zn and Se precursors. These films, grown on various substrates, show bright blue ‘edge’ emission accompanied by donor-acceptor pair emissions in the blue, green and red spectral regions. Red, green and blue emissions mixed together give a white color, with a color temperature between 2400 and 4500 K depending on a layer thickness and temperature. ZnSe grown by ALD is in consequence a promising material for the fabrication of semiconductor-based white light emitting thin film electroluminescence displays.     

ZnCl2-assisted Synthesis of ZnSe Polycrystal

A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature (～1000 C). ZnSe polycrystal was obtained in the closed-tube systems with Zn-Se, Zn-Se-Zn(NH3)2Cl2, Zn-Se-NH4Cl and Zn-Se-ZnCl2. The as-synthesized samples were tested by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and analyzed by thermodynamic numerical method. The results demonstrate that the synthesis efficiency is higher than 99.96% for Zn-Se-ZnCl2 system at around 1000 C for 3 weeks. It also exhibits that not only temperature, but also low apparent ratio of volume and surface area of the source materials and higher ZnCl2 content are required to achieve high synthesis efficiency. A SeCl transporting reaction synthesis process is proposed based on the thermodynamic analysis.     

Development and Characterization of a Factor V-Deficient CRISPR Cell Model for the Correction of Mutations

Factor V deficiency, an ultra-rare congenital coagulopathy, is characterized by bleeding episodes that may be more or less intense as a function of the levels of coagulation factor activity present in plasma. Fresh-frozen plasma, often used to treat patients with factor V deficiency, is a scarcely effective palliative therapy with no specificity to the disease. CRISPR/Cas9-mediated gene editing, following precise deletion by non-homologous end-joining, has proven to be highly effective for modeling on a HepG2 cell line a mutation similar to the one detected in the factor V-deficient patient analyzed in this study, thus simulating the pathological phenotype. Additional CRISPR/Cas9-driven non-homologous end-joining precision deletion steps allowed correction of 41% of the factor V gene mutated cells, giving rise to a newly developed functional protein. Taking into account the plasma concentrations corresponding to the different levels of severity of factor V deficiency, it may be argued that the correction achieved in this study could, in ideal conditions, be sufficient to turn a severe phenotype into a mild or asymptomatic one.     

锌基/(C、Si)复合材料的界面结合特征

锌基 /( C、Si)复合材料由石墨和硅粉在 60 0～ 70 0℃加入锌基合金熔体获得。结果表明 :C、Si颗粒可加入锌基合金且分布均匀。热力学计算得出 ,C、Si与锌基合金基体不发生界面反应 ,为机械结合。