As an important refractory metal, tungsten (W) has unique physical-chemical properties, and the applications of high-quality tungsten NPs with uniform particle size, high purity, and good particle dispersion in industrial fields are highly desirable. Herein, the integration of tungsten metallurgical purification and nanoparticle preparation is achieved by the hydrogen arc plasma method. In the process of purification, on the condition of arc current of 250 A, hydrogen concentrations of 30 vol%, purification time of 40 min, and gas pressure of 60 kPa, the highest impurity removal rate is achieved. The active H+ is able to react with impurities to generate metal hydride (MH, M = Al, Cr, Mg, and Fe), which promotes the removal rate of impurity elements. During the preparation of nanoparticles (NPs), the as-prepared tungsten NPs with an average particle size of 44.1 nm have a regular spherical structure, high purity, and a relatively uniform particle size distribution. When the hydrogen con-centration is controlled at 50 vol%, the extremely high temperature promotes the evaporation of tungsten. Meanwhile, the active H+ reacts with tungsten to form tungsten hydride (WH), further increasing the evapo-ration rate of tungsten. According to the above results, the hydrogen arc plasma promotes the simplification of the production process steps of high purity tungsten NPs and reduces the industrialized production cost of high-quality refractory metal NPs.

随着社会的发展,科学技术的不断提高,人们发现稀土金属在提高产品质量、增强产品性能等方面已表现出其独特的优势,但也存在稀土材料传统制备方法周期长、高端应用领域研究不够深入等问题.文中主要介绍了离子交换法、热分解法、水热/溶剂热法、共沉淀法和溶胶-凝胶法等制备稀土材料的最新进展,并着重介绍了稀土在永磁材料、发光材料、催化材料、储氢材料和高纯靶材等方面的高端应用.根据以上分析,革新稀土制备方法和挖掘新的稀土材料,使其在电子信息、汽车尾气净化、航空航天以及生理医疗等领域发挥更大的作用.最后,对提高稀土产品附加值、开发稀土新材料、优化稀土生产工艺及发展稀土高端应用进行了展望.

The environmental-friendly synthesis of nanostructural aluminium nitride with high purity and good dispersity properites is regarded as a technical issue. In this paper, an arc discharge with assistance of direct nitridation has been put forward to synthesize aluminium nitride nanoparticles that simultaneously possess the high purity of more than 97%, the average particle size of 99.1 nm, and the specific surface area of 60.8 m2 g-1. Compared with the aluminium nitride prepared by direct nitridation of aluminium nanoparticles, the unique framework of the satellite structural and small-sized aluminium nanoparticles attached on larger-sized aluminium nitride nanoparticles is prepared by arc discharge, which can prevent effectively agglomeration and coalescence of aluminium nitride nanoparticles in the next nitridation process. In addition, the direct nitridation process requires a low temperature of 600 degrees C for 2 h, because the nonstructural aluminum particles are evenly distributed on the surface of aluminum nitride and process the low average diameter of 40 nm. The work provides an efficient technique to open up the possibility of technological advancement for preparing metal nitride nanoparticles with high purity and good dispersity.