Review
Chemistry, Physical
Mihail Secu, Corina Secu, Cristina Bartha
Summary: Rare-earth doped oxyfluoride glass ceramics can be tailored for optical applications with high transparency and luminescence properties, while maintaining thermal and chemical advantages of oxide glasses. Sol-gel chemistry offers a flexible synthesis approach with control over purity and homogeneity, along with compositional flexibility. This review focuses on optical properties and processing influences on RE-doped luminescent nanocrystals, discussing perspectives and future development directions.
Review
Chemistry, Inorganic & Nuclear
Zi-Xia Chen, Wenlong Liu, Sheng-Ping Guo
Summary: Metal chalcophosphates exhibit chemical and structural diversity due to the different ways phosphorus-sulfur/selenium anionic groups connect. Rare earth metals, known for their unique magneto-optical properties, have attracted great interest and have been widely studied. Recent research progress on rare earth chalcophosphates, focusing on their structures and physical properties, is summarized in this review. It is believed that rare earth chalcophosphates have the potential to be multifunctional materials, and this summary aims to provide insights for the development of new rare earth chalcophosphates.
COORDINATION CHEMISTRY REVIEWS
(2023)
Article
Engineering, Electrical & Electronic
Liqiong Shao, Aimin Sun, Yanchun Zhang, Lichao Yu, Nanzhaxi Suo, Zhuo Zuo
Summary: The Ni-Mg-Co magnetic ferrite nanoparticles doped with Al3+, La3+, Ce3+, Pr3+ and Sm3+ exhibit a single-phase spinel structure, with decreases in average crystallite size after rare-earth ion doping and an increase in size after Al3+ doping. The magnetic properties, including remanent magnetization, square degree, coercivity rectangle degree and anisotropy constant, all show variations after doping with rare-earth ions and Al3+.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2021)
Article
Chemistry, Analytical
Mani Teja Bodduluri, Bjoern Gojdka, Niklas Wolff, Lorenz Kienle, Thomas Lisec, Fabian Lofink
Summary: This paper introduces a new technique called PowderMEMS, which uses atomic layer deposition (ALD) to agglomerate micron-sized powders and fabricate permanent micromagnets. The magnetic, thermal stability and corrosion stability of NdFeB micromagnets prepared using PowderMEMS are systematically investigated through a series of experiments. The results demonstrate the durability of PowderMEMS micromagnets and their potential applications in various fields.
Article
Engineering, Chemical
Chang Du, Shuai Ma, Meiying Xie, Fan Yang, Zhigang Zhao, Yun Chen, Ying Ma
Summary: This paper presents a new method for recycling permanent magnet waste using betaine hydrochloride ([Hbet]Cl) solution extraction. Orthogonal experiment method was employed to analyze the leaching process and identify the primary and secondary factors affecting the leaching results. Optimum leaching conditions were determined, which resulted in excellent leaching rates for various metals and minimal iron oxide residue. Compared to conventional lixiviants, this method exhibited better leaching rate and selectivity, and conformed to established chemical properties. It is characterized by high recovery rate, strong selectivity, environmental friendliness and low cost.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Elif Emil Kaya, Ozan Kaya, Srecko Stopic, Sebahattin Gurmen, Bernd Friedrich
Summary: Neodymium iron boron (NdFeB) magnets play a crucial role in various technological applications due to their exceptional magnetic properties. It is expected that the production of NdFeB will increase significantly in the near future, leading to higher demand for rare earth elements (REE) and making their recovery essential. This study proposes a new promising process flowsheet for the recovery of rare earth elements from NdFeB magnets, which involves acid baking, hydrolysis, and ultrasonic spray pyrolysis methods. The synthesized mixed REE-oxide powders were characterized by X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive X-ray analysis, showing spherical particles with sizes between 362 and 540 nm.
Article
Chemistry, Applied
Jing Chen, Hongyi Yang, Guangqing Xu, Pengjie Zhang, Jun Lv, Wei Sun, Bingshan Li, Jun Huang, Dongmei Wang, Xia Shu, Yucheng Wu
Summary: Rare earth passivation can significantly enhance the corrosion resistance performance of Zn coated NdFeB magnets, and the passivation layer has a positive effect on maintaining the NSS time of the magnets.
JOURNAL OF RARE EARTHS
(2022)
Article
Chemistry, Inorganic & Nuclear
Xiao Chen, Yan Peng, Runli Gao, Hongmei Wang, Chengxin Pei
Summary: An isostructural series of rare earth complexes ligated by organoarsinate ligand was successfully synthesized. These complexes exhibit chain-like structures and display magnetocaloric effect and characteristic emission bands.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Srecko Stopic, Buse Polat, Hanwen Chung, Elif Emil-Kaya, Slavko Smiljanic, Sebahattin Gurmen, Bernd Friedrich
Summary: NdFeB magnets are widely used in various technological applications due to their remarkable magnetic properties. However, their limited recycling and China's monopoly on rare earth elements supply pose economic and environmental challenges. This paper proposes a pyrometallurgical recycling method for end-of-life NdFeB magnets by oxidizing them in air. The experimental results show that the material is completely oxidized at 1100 degrees C, resulting in the formation of various metal oxides.
Article
Engineering, Chemical
Dominik Boehm, Konrad Czerski, Stephan Gottlieb, Armin Huke, Goetz Ruprecht
Summary: This article presents a sustainable separation concept for large-scale recycling of NdFeB magnets. It combines two separation concepts from the literature: selective pre-separation by in situ chlorination and evaporation, and subsequent distillation for high-purity recovery of recyclable material components, including Rare Earth Elements (REEs).
Article
Environmental Sciences
Fulin Mao, Nengwu Zhu, Wen Zhu, Bowen Liu, Pingxiao Wu, Zhi Dang
Summary: By utilizing a hydrometallurgical coupling process involving mechanical activation and selective acid leaching, the recovery of REEs from discarded NdFeB magnets with high REE content can be achieved efficiently. The ball milling activation method enhances the reactivity of samples, promoting the leaching efficiency and leaching speed of REEs. Under optimal conditions, the leaching efficiency of REEs can reach up to 99% with low hydrochloric acid consumption, resulting in a final purity of recovered rare earth oxides up to 99.9%.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Engineering, Chemical
Zhang Zhihan, Wang Zhi, Wang Dong, Lin Yong, Xiao Wanhai, Liu Chenghao, Liuyimei Yang, Wu Jian, Li Guobiao
Summary: Rare earth elements (REEs) are crucial for industrial development, and it is important to recycle them from waste containing REEs; however, challenges of high acid consumption and heavy pollution still persist. This study found that the insoluble phase of NdFeO3 significantly inhibited the leaching efficiency of REEs in roasted NdFeB waste. Mechanical activation was an effective method to destroy the structure of the insoluble NdFeO3 phase and increase the leaching efficiency of REEs. This work provides a green strategy and theoretical basis for efficiently recovering REEs from NdFeB waste.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Engineering, Environmental
Anting Ding, Chuanying Liu, Xingwang Zhang, Lecheng Lei, Chengliang Xiao
Summary: This study developed an alternative green route for the selective recovery of rare earth elements from spent NdFeB magnets using a purely inorganic zinc salt. The method achieved a high separation factor and close to 100% purity of the recovered product. Compared to traditional hydrometallurgical processes, this method significantly reduces energy consumption and chemical inputs.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Xueyun Zhou, Jun Wang, Dongsheng Yao
Summary: In this study, RE0.01Ni0.3Zn0.4Mn0.3Fe2O4 (RE=Fe, La, Nd, Sm, Gd, Dy, Yb) ferrites with precisely controlled composition were prepared. It was found that the lattice constant decreases with the increase of atomic number of rare earth. The infrared spectra showed changes in the tetrahedral and octahedral bonds. The introduction of rare earth slightly reduced the saturation magnetization and initial permeability, but had the same effect on Ms. These ferrites exhibited spin glass state or superparamagnetism at high temperature, and Sm, Gd, and Dy doped ferrites displayed unique dielectric properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Lingyao Meng, Jian Shang, Mengjiu Zhang, Aijun Xie, Yue Zhang
Summary: Rare-earth vanadiumizing layers were prepared on the surface of GCr15 steel using powder pack cementation, and the growth kinetics of the layers were investigated. The experimental results showed that the thickness and microhardness of the layers increased with the increase in heating temperature and holding time.
