Magnetic structure analysis of (Nd1-xDyx)2Fe14B (x = 0, 0.125)
The 58th Annual Magnetism and Magnetic Materials (MMM) Conference
Saito, Kotaro ( KEK )
Inami, Nobuhito ( KEK )
Ueno, Tetsuro ( NIMS )
Otori, Hiroyuki ( KEK )
Takeichi, Yasuo ( KEK )
Sagayama, Ryoko ( KEK )
Kumai, Reiji ( KEK )
Ishigaki, Toru ( Ibaraki University )
Yano, Masao ( TOYOTA )
Kato, Akira ( TOYOTA )
Miyamoto, Noritaka ( TOYOTA )
Shoji, Tetsuya ( TOYOTA )
Manabe, Akira ( TOYOTA )
Kaneko, Yuji ( Toyota Central R&D Labs. )
Ono, Kanta ( KEK )
Abstract
Dy doping enhances the coercivity of Nd-Fe-B magnet at high temperatures.
Despite of the industrial importance of large coercivity at high-temperature environments, the effect of Dy doping is still unclear.
To understand a mechanism of the enhancement, we start from the magnetic structure analysis.
There is a previous report on the magnetic structure of Dy-doped Nd2Fe14B at room temperature.
In 1986, Yelon et al. reported the magnetic structure of (Nd0.5Dy0.5)2Fe14B and mentioned preferential occupancy of rare earth ions between two sites depending on the volumes of the ions[1].
Concerning the two sites for magnetic rare earth ions, they introduced two positional, four magnetic moment, and one site occupancy parameters in their Rietveld refinement.
As partly mentioned in the paper, it is very difficult to refine those parameters with the intensities from magnetic scattering because they may cancel out their contributions to the intensities each other and fitting evaluation may easily fall into local minima.
Magnetic moments and preferential occupancy of rare earth ions are crucial information for theoretical calculation of magnetic properties and thus we take the absence of follow-ups for the study seriously.
Powder neutron diffraction data of (Nd1-xDyx)2Fe14B (x = 0, 0.125) were taken with a TOF diffractometer iMATERIA at J-PARC/MLF, Tokai.
11B was used for the elimination of neutron absorption by 10B.
To increase the quality and reliability of the magnetic structure refinement, we have also carried out synchrotron x-ray diffraction measurements which only give us crystal structure information using IP diffractometer at BL-8A/8B installed in Photon Factory, Tsukuba.
Fig. 1 shows the TOF profile of Nd2Fe14B and the result of Rietveld refinement.
We will present the results of combined Rietveld refinements of two experimental methods and discuss positional parameters and preferential occupancy of Dy ions.
Despite of the industrial importance of large coercivity at high-temperature environments, the effect of Dy doping is still unclear.
To understand a mechanism of the enhancement, we start from the magnetic structure analysis.
There is a previous report on the magnetic structure of Dy-doped Nd2Fe14B at room temperature.
In 1986, Yelon et al. reported the magnetic structure of (Nd0.5Dy0.5)2Fe14B and mentioned preferential occupancy of rare earth ions between two sites depending on the volumes of the ions[1].
Concerning the two sites for magnetic rare earth ions, they introduced two positional, four magnetic moment, and one site occupancy parameters in their Rietveld refinement.
As partly mentioned in the paper, it is very difficult to refine those parameters with the intensities from magnetic scattering because they may cancel out their contributions to the intensities each other and fitting evaluation may easily fall into local minima.
Magnetic moments and preferential occupancy of rare earth ions are crucial information for theoretical calculation of magnetic properties and thus we take the absence of follow-ups for the study seriously.
Powder neutron diffraction data of (Nd1-xDyx)2Fe14B (x = 0, 0.125) were taken with a TOF diffractometer iMATERIA at J-PARC/MLF, Tokai.
11B was used for the elimination of neutron absorption by 10B.
To increase the quality and reliability of the magnetic structure refinement, we have also carried out synchrotron x-ray diffraction measurements which only give us crystal structure information using IP diffractometer at BL-8A/8B installed in Photon Factory, Tsukuba.
Fig. 1 shows the TOF profile of Nd2Fe14B and the result of Rietveld refinement.
We will present the results of combined Rietveld refinements of two experimental methods and discuss positional parameters and preferential occupancy of Dy ions.
