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.     

Corrosion Resistance of an electrodeposited Zinc Coating Containing CeO2 Nanoparticles

A Zinc coating containing CeO2 nanoparticles has been deposited by electrodeposition in a zinc plating bath.The content of CeO2 in the coating is 0.22 mass%. The results of weight loss experiments and electrochemistry tests show that corrosion resistance of the Zinc coating containing CeO2 nanoparticles is remarkably improved in contrast to the pure zinc coating in 0.5 M MgSO4 solution. The effects of CeO2 microparticles on the corrosion resistance of the zinc coating have been studied, the results show that CeO2 microparticles have no effect on the corrosion resistance of the zinc coating. SEM and XRD experiments suggest that the presence of CeO2 nanoparticles in the coating causes the modification of the surface morphology and preferential orientation of the crystal planes; therefore, the reason for the enhancement of corrosion resistance is mainly related to improvement of the structure of the coating.     

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.     

In situ observation of phosphorous and non-phosphorous antiwear films using a mini traction machine with spacer layer image mapping

Since 1940s the principal source of an antiwear additive in crankcase applications has been due to a family of additives known as zinc dialkydithiophosphate (ZDDP). In this study, we have applied a novel technique, the mini traction machine with spacer layer image mapping (MTM SLIM), to study film formation characteristics of monoblend oils containing only basestock and ZDDP and also fully forrmulated oils containing a boron antiwear additive. The purpose of this study was initially to understand the build up of ZDDP film and then to establish whether boron compounds alone could provide significant antiwear films under mixed rolling and sliding contact.     

分光光度法测定润滑油中的微量锌

在pH为8.3的硼砂-盐酸缓冲溶液中,应用水杨基荧光酮(SAF)-溴化十六烷基三甲氨(CTMAB)显色体系测定润滑油中的微量元素锌,建立测定润滑油中微量锌的快速分析方法。通过一系列实验的考察,结果表明,含锌量在0-25μg/25mL内服从比尔定律,摩尔吸光系数为ε570=9.1×104L.mol-1.cm-1,线性范围为0-60μg/10mL,加标回收率为97.21%~101.1。实验方法简便、灵敏、准确。     

线性规划-导数分光光度法同时测定Cu、Zn、Ni的方法研究

用单纯形线性规划算法解析一阶导数先谱数据，对以5－Br－PADAP为显色剂，CPB为增效剂的Cu、Zn、Ni三组分混合体系的同时测定进行了研究。该法灵敏度高，所需波长点少，计算速度快，可不经任何分离掩蔽即可达到同时测定三组分混合物的目的．对标准合成样品进行了测定，结果令人满意．     

天然水及头发中痕量锌的单扫描示波极谱测定

本文在文献[1]的基础上,进一步研究了在乙二胺介质(pH11.2)中锌的单扫描示波极谱测定方法,确立了最适条件。锌浓度在1.0×10~(-7)、5.0×10~(-6)mol·dm~(-3)之间与波高呈良好的线性关系,检出下限低达5.0×10~(-8)mol·dm~(-3)。该法无需前处理即可直接测定多种天然水中痕量锌,头发样品中的锌经常规硝化处理后也能方便测定,其相对标准偏差为1.6％,结果令人满意。本文认为,此法用于建立水样中痕量锌测定的标准方法是可行的。     

工业废水中金属元素的测定

工业废水中金属离子对水环境造成污染,并危及人体健康,应准确进行测定.论述了原子吸收分光光度法测定工业废水中金属元素的原理,重点论述了测定Zn的条件、范围、干扰等因素,总结了测定锌的条件及测定结果;实验证明,用原子吸收分光光度法测定工业废水中的Zn元素,可取得较好的结果.     

硫化锌矿常压氧化浸出过程的研究

研究了以ＨＮＯ３和ＮＯ２为氧化剂硫酸浸出硫化锌矿的过程。指出Ｚｎ＾２－、Ｆｅ＾２＋、Ｆｅ＾３－等通过硫膜层的扩散是整个过程的控制步骤。并用正并试验的方法对矿粉粒度、酸浓度、酸耗量、浸出温度和时间等因素对浸出率的影响进行了详细的考察，获得了较优的浸出工艺条件；在此条件下锌出率达９５％以上。     

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.