First-principles study on substitution effects in Nd2(Fe, X)14B (original) (raw)
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Magnetic behavior of Nd 2 Fe 17x Mx (M=Mn, Ga): A comparative study
Revista Mexicana de Fisica
Recibido el 25 de junio de 2010; aceptado el 08 de noviembre de 2010 Samples of Nd2Fe17−xMx, with M = Mn and Ga, were prepared by arc melting and homogenized by annealing at T = 1273 K. Afterwards, specific heat, impedance, X-ray diffraction, Mossbauer spectroscopy, and thermogravimetric measurements were carried out. Results indicate that temperature dependence on impedance changes at transition temperature. Specific heat measurements show an anomaly at transition temperature and this is compared with data reported for Y 2 Fe 17 and Pr 2 Fe 17 . Specific heat jump ∆C p for Nd 2 Fe 17−x Mn x as a function of x at transition temperature was obtained from experimental data; this exhibits a decreasing behavior but different from that predicted by the expression derived from the molecular field theory. This disagreement could be attributed to competition between enlarged Fe sublattice and reduction of magnetic moment when Mn is substituted by Fe at preferential sites. On the other hand,...
Nd-rich Effects on Structural and MagneticProperties of Nd2Fe14B Magnets
American Journal of Mechanical and Industrial Engineering, 2017
Hard magnetic material Nd 2 Fe 14 B was synthesized via powder metallurgy technique. The magnetic powder Nd 2 Fe 14 B was produced by mixing Neodymium powder (Nd), Iron powder (Fe), and Boron powder (B) in a vacuum and then followed by firing process at 720ºC. The Nd 2 Fe 14 B powder produced was grained with addition of 0.3g and 0.7g Neodymium respectively. The powder was sintered at 720ºC. The characterization of magnetic properties by using VSM and phase analyse using XRD. SC-70 was used as detector with 40 kV and 30 mA (CuKα/1.5418A o). The scan range was 10 o-90 o with a speed of 2 deg/min. The crystal structure of the samples were determined based on data obtained from XRD pattern. The tetragonal crystal structure of Nd 2 Fe 14 B was confirmed with lattice parameters 'a' = 'b' = 8.707Å and 'c' = 12.203Å. The result showed that remanence magnetization (Mr). The maximum energy product (BH) max of Nd 2 Fe 14 B was increased from 8,56 KGOe to 16,59 KGOe with adddition of 0,3g Nd. The BH max reached 17,83KGOe when 0,7g Nd-rich was introduced.
Effect of Tb substitution on the magnetic properties of exchange-biased Nd2Fe14B/Fe3B
Journal of Materials Science, 2007
Tb-substituted (Nd,Tb) 2 Fe 14 B/Fe 3 B nanocomposite ribbons have been synthesized by melt spinning of Nd 3 Tb 1 Fe 76 Cu 0.5 Nb 1 B 18.5 alloys. Tb substitution has significantly enhanced the value of coercivity and Curie temperature. Highest value of coercivity has been obtained as 4.76 kOe for the sample annealed at 953 K for 10 min. Curie temperature of Tb substituted sample, Nd 3 Tb 1 Fe 76-Cu 0.5 Nb 1 B 18.5 is 549 K while Curie temperature of the sample without Tb, Nd 4 Fe 76 Cu 0.5 Nb 1 B 18.5 is 535 K. Recoil hysteresis loops measured along the major demagnetization curve are steep having small recoil loop area. Temperature dependence of coercivity, remanent ratio and maximum energy product have been measured for the sample annealed at 893 K and 923 K for 10 min. At 5 K, coercivity and maximum energy product of the sample annealed at 893 K for 10 min are 5.2 kOe and 11.5 MGOe respectively and the sample annealed at 923 K for 10 min are 6 kOe and 13.1 MGOe respectively.
ChemInform, 2014
The properties of magnetic material of Nd-Fe-B are highly affected by various factors such as particle size, magnetic anisotropy, phase purity and crystal structure. Incorporation of excess neodymium was carried out in various percentages so that it will adjust the proportion of neodymium in the host crystal after reduction treatment and finally help to improve magnetic property of a material. The interdiffusion of Nd-Fe and boron was studied for various compositions and their effect on magnetic property was understood with theoretical concepts. The factors such as amount of hard and soft phase in the reduction treated product is also responsible for the possible exchange coupling between hard and soft phase magnets for better magnetic properties.
Magnetic x-ray investigation at the L[sub 2,3] edges of Nd in Nd[sub 2]Fe[sub 14]B
Journal of Applied Physics, 1998
A systematic study of x-ray magnetic circular dichroism, x-ray resonant magnetic scattering, and resonant inelastic x-ray scattering at the L 2,3 edges of Nd on Nd 2 Fe 14 B is presented. The combined information allows to assign a dipolar or quadrupolar origin to different features appearing in the experimental spectra and to study the thermal dependence of the Nd moment orientation below the spin reorientation transition which takes place at T SRT ϭ135 K.
Applied Physics Express, 2015
To identify the possible mechanism of coercivity (H c) degradation of Nd-Fe-B sintered magnets, we study the roles of the exchange field acting on the 4f electrons in Nd ions and theoretically investigate how the variation of the exchange field affects the values of the magnetic anisotropy constants K 1 and K 2. We find that, with decreasing exchange field strength, both values decrease as a result of the lower asphericity of the 4f electron cloud, indicating that the local anisotropy constants might become small around the grain boundaries where the exchange fields are decreased owing to the smaller coordination number. wave function of the 4f electrons, and N R is the density of RE ions. Note that the CEF parameter