We focus on dried fruits containing crystalline sucrose chiefly, and study a method for identification of sucrose-radicals in ESR spectra of irradiated dried fruits. We evaluated g-values and widths of ESR signals of irradiated dried fruits and sucrose respectively. The result showed it might be possible to identify sucrose-radicals by g-values and widths. We tried the establishment of criteria for the judgment that the sample has been irradiated. As a result, criteria may be established by normalized peak height of ESR signals. The peak height can be normalized by using standard irradiated alanine pellets.
Concentrations of 134Cs, 137Cs and 40K in 73 supplements marketed in Japan were measured by gamma-ray spectrometry. In all supplements, 134Cs was not detected. On the other hand, 137Cs was detected in 9 supplements, and the concentrations of 137Cs in them were in the range of 2.3-190 Bq/kg. There was a tendency that concentrations of 137Cs in supplements made from materials accumulating 137Cs, such as mushrooms and blueberries, were high. Furthermore, 40K was detected in 56 supplements at levels of 17.6-11600Bq/kg. The committed effective dose of 137Cs in adults by annually taking supplements was estimated to be about 2.9μSv.
For magnetic structure refinement of bulk materials, the neutron diffraction technique is the most reliable probe. In this short article, basic information of magnetic structure refinement by powder neutron diffraction;in particular, actual process of data analysis will be presented with real data. First, the author will explain some typical commensurate and incommensurate structures, and how the structure represent by propagation vector k, which is the one of the most important value for magnetic structure refinement. The author will show the magnetic structure factor, and explain the meanings of each factor of which the magnetic structure factor consists. Each process from neutron diffraction experiments to the analysis for practical magnetic structure refinements will be explained in the case of the rare earth compound TmB2C2. In the section, information on some diffractometers in Japan which are suitable for magnetic structure refinements will be given. Finally, information on some important and powerful analysis softwares for Rietveld analysis and a quite sophisticated technique, the representation analysis technique, will be presented.
As an example of application of neutron diffraction, magnetic properties of high-performance permanent magnets were reviewed, laying emphasis on rare-earth containing magnets. After introducing a development history of permanent magnets in the last century, basic properties and origin of magnetic anisotropy in ferromagnets were explained in terms of crystalline-electric-field interaction acting on a rare-earth ion. Main part of this article was devoted to a description of the strongest Nd-Fe-B magnet, main phase of which has been assigned to be Nd2Fe14B intermetallic compound by powder neutron diffraction experiments. Structural and magnetic properties in a series of Nd2Fe14B-type compounds were described systematically, including inelastic neutron scattering, small-angle neutron scattering, and high-field magnetization experiments on single crystal samples. Recent issue of Dy-containing Nd-Fe-B magnets for applications in a driving motor of the hybrid electric vehicle was mentioned in the final chapter, which consequently motivated and stimulated a research to enhance the coercivity of the Nd-Fe-B magnets with less Dy content.
Application of polarized neutron scattering to microscopic analysis of Fe16N2 nano-particles for the high-density magnetic recording tape is presented. The microscopic magnetic moment is obtained by the polarized neutron diffraction and information about the surface non-magnetic layer by the small-angle polarized neutron scattering. The experimental results are described for the particles with diameters from 15 to 19 nm.
Recent progresses of neutron diffraction under high magnetic fields are introduced. A compact pulsed magnet is installed in a reactor and experiments up to 30T can be achieved without modification of conventional spectrometers. In pulsed neutron source, pulsed magnet system up to 50T has been developed. The first feasibility study was successfully performed up to 40T. Those advances will open a new stage in the use of neutron diffraction in high magnetic fields in both fundamental and applied sciences.
Magnetic structure of typical multiferroic materials RMnO3 and RMn2O5 (R:rare earth) has been investigated by neutron diffraction. Magnetic structure analysis using single crystal revealed that both the materials have a cycloidal magnetic structure, where ferroelectricity arises. Polarized neutron diffraction under electric field found the one-to-one correspondence between the direction of cycloidal rotation (spin chirality) and the direction of the electric polarization, evincing that the electric polarization is directly induced by the cycloidal magnetic order.
Magnetic structure in field-induced ferroelectric phase of a multiferroic material CuFeO2 has been investigated to be a proper-helical magnetic structure by in-field neutron diffraction. Subsequently, polarized neutron diffraction under electric field revealed the one-to-one correspondence between the spin helicity of the proper-helical magnetic structure and electric polarization vector, clearly showing that the electric polarization is directly induced by the proper-helical magnetic order.