Magnetism and phase stability of R(Co,M)7 pseudobinary intermetallics with TbCu7-type structure

Abstract

Pseudobinary RCo 7−x M x intermetallic compounds with TbCu 7 -type structure have been synthesized, and their structural and magnetic properties have been investigated using powder x-ray diffraction and magnetic measurements. Based upon the structural analysis, the stabilized element M occupies the 2e or the 3g position depending on its electronegativity. RCo 7−x M x compounds exhibit ferromagnetic order with high Curie temperature. In addition, the uniaxial magnetocrystalline anisotropy is observed in SmCo 7−x M x intermetallics. The magnetic moments have been investigated using a modified magnetic valence model with the equationthe magnetic moment contributed by 4f transition metal is corrected from its chemical valence numbers of rare earth in the original magnetic valence model to the theoretical value of g J B J. It is also assumed that the nonmagnetic metal has no contribution to the moment. The corrected model can also be used to calculate the moments of the other strong ferromagnetic intermetallics such as R -͑T , M͒ 1:5, 2:17, and R 2 Fe 14 B, etc. This model could estimate and even predict the moments as long as the composition of the ferromagnetic alloy is known.

Research progress on high performance Nd‐Fe‐B permanent magnet

“…Curie temperature of the main phase is sensitive to the Fe-Fe and Nd-Fe bond lengths, our study shows a short bond distance is beneficial for the high Curie temperature. The magnetism of Nd-Fe-B alloys was studied with a modified magnetic valence model [8,9].…”

“…The NIM-2000 auto hysteresis loop tracer was used to investigate the magnetic properties. The magnetism of Nd-Fe-B alloys was studied with a modified magnetic valence model [8,9]. (1) Table 1 The refined structural parameters of NdFeB Main phase before (B) and after (A) striping process.…”

Effects of Hf and CNTs on structure and magnetic properties of TbCu7-type Sm–Co magnets

“…However, pure SmCo 7 phase can not steadily exist, so a third element such as Si, Cu, Ga, Nb or Hf, is necessary to stabilize the TbCu 7 -type Sm-Co 1:7 phase and to improve its magnetic properties. Guo and his coworkers [3][4][5][6][7] directly prepared some Sm-Co 1:7 intermetallic compounds by arc melting. Among those third elements M, Hf has been reported the most powerful both in stabilizing the TbCu 7 -type structure and in enhancing its magnetocrystalline anisotropy field, meanwhile, it possesses high magnetization.…”

Study on the Magnetic Characteristics of Anisotropic SmCo7-type Alloys Synthesized by High-energy Surfactant-assisted Ball Milling

“…In comparison, the Sm(Co,M) 7 (M = stabilizing element) compounds with the TbCu 7 -type structure (space group P6/mmm) possess a higher predicted Curie temperature, a high magnetic anisotropy field, and a low intrinsic coercivity temperature coefficient [10]. Thus, the SmCo 7 -type alloys could be suitable for development as permanent magnets for high temperature applications.…”

“…A small amount of the third element (i.e. Cu, Zr, Ti, Hf, and Si) can stabilize the Sm-Co phase with the TbCu 7 -type structure [6][7][8][9][10]. Hence, Cu and Zr were doped as the third elements to stabilize the SmCo 7 -type phase in this paper.…”