Origins of the significant improvement in nanocrystalline Samarium–Cobalt’s magnetic properties when doping with Niobium

Selecting Doping Elements by Data Mining for Advanced Magnets

“…From the abovementioned MGI database of Sm-Co materials, a data set of saturation magnetization was extracted (which is provided in Section S1 in the Supporting Information), and it contains data of 214 kinds of materials from various resources published in 40 years from 1978 to 2018. ,,,,− The information related to saturation magnetization includes the Sm-Co matrix with a certain atomic ratio ( x matrix = ( x Co + x M )/ x Sm ), doping element (denoted as “M”), doping concentration ( x doping = x M / x Co ), processing of material ( C proc ), form of the material for testing ( C form ), grain size ( d ), and so on. It is known that, for a data set, machine learning can generate a predictive model, which can be applied to design new materials.…”

“…Among various properties of permanent magnetic materials, saturation magnetization ( M s ) determines the upper limit of the remanence and restricts the maximum magnetic energy product of the material. , A high level of saturation magnetization combined with an increased coercivity, which is dependent on the modifications of the microstructure and processing of the material, will lead to an excellent comprehensive magnetic performance with a large maximum energy product. From the existing experimental results, there are multiple factors affecting the saturation magnetization in an intricate way. − In comparison with experiments, the first-principles calculations can predict magnetic moment for ideal crystals regardless of the processing techniques and microstructural configurations . For the rare-earth/transition-metal magnetic alloys, the magnetocrystalline anisotropy originating from 3d–4f exchange coupling and magnetic moment of atoms composed of the spin and orbital magnetic moments can be calculated by first principles. , Considering the influence of 4f electrons and requirement of nonlinear computation, the full-electrons method is generally used in the first-principles models to achieve a high calculation accuracy .…”

“…In this respect, we spent over 10 years building up a specific database for Sm-Co systems, which contains both experimental and computational data for ∼1050 alloys published in the literature for decades, and some of them are used as references in this work. − ,,,− More importantly, we embedded in the database the related information search regarding composition, processing, microstructure, properties, and references of the material, which is unique from other material databases. The above specialized database may be considered as a “Materials Genome Initiative (MGI) , database of Sm-Co materials” according to its characteristics.…”

Investigation on the structures and magnetic properties of carbon or nitrogen doped cobalt ferrite nanoparticles

“…Generally, both metal and nonmetal elements are the normal origin of doping elements. The metal elements are more inclined to be doped into many magnetic materials 3 , 4 , 6 , 18 – 23 and some nonmagnetic materials 10 , 12 , 24 , 25 , while the nonmetal elements (like carbon, nitrogen, phosphor, and sulfur, etc.) usually focus on the doping of nonmagnetic materials, such as titanium dioxide 26 , 27 , carbon materials 28 , 29 , silicon materials 30 , 31 and other nonmagnetic materials 11 , 24 , 32 .…”

Modeling and experimental studies of Hf-doped nanocrystalline SmCo7alloys

“…To solve this problem, we adopt the first-principles density functional theory (DFT) and combine it with experimental investigations. Although there were some reports on SmCo 7based systems using first-principles calculations, [26][27][28][29] few studies were related to phase decomposition, and little attention has been paid to the influence of doped elements on the magnetic properties. Based on our previous work, 30 here we focus our attention on the effects of the Hf element on the structure and magnetic performance of nanocrystalline SmCo 7 -based alloys.…”