The introduction prior to series of papers on the application of neutrons for materials science (MS) in this issue starts with a brief summary of neutron scattering research history in Japan; from the individual activity by Motoharu Kimura at RIKEN early around 1940s to those at present era of world leading neutron science facilities of both JRR3 research reactor and JPARC of the largest proton Accelerator complex in Tokai. Then physical properties of low energy neutrons applied to MS as well as such neutron sources are also reviewed (http://www.jstage.jst.go.jp/browse/jvsj2).
We have been developing a multi-purpose pattern-fitting system RIETAN-FP and a three-dimensional visualization system VENUS, which have been extensively used for structure refinements of various metal and inorganic materials from neutron powder diffraction data. At first, their outlines and the history of their developments are shortly looked back. The second part describes procedures for analyzing collinear magnetic structures with the combination of VESTA in the VENUS system and RIETAN-FP by taking BiCoO3 for instance. Finally, a new C++ program, Dysnomia, for the maximum entropy method is introduced with emphasis on its new features. Dysnomia excels its predecessor, PRIMA, in computation speed, memory efficiency, scalability, and reliability. In particular, addition of a normal-distribution constraint is effective in obtaining nuclear-density distribution that is physically and chemically reasonable.
Neutron diffraction is the only method by which residual stresses inside materials at centimeter-order depth can be measured nondestructively. Residual lattice strains in (hkl) can be evaluated from the shift of the diffraction peak from its original position under the stress-free condition. Residual stresses can be calculated by applying Hooke's law to lattice strains measured in three orthogonal directions. In addition, the neutron diffraction method can evaluate macroscopic deformation of engineering materials by measuring microstructural factors such as microstrains. Therefore, the neutron diffraction technique is very helpful in the design and development of engineering components, as well as in studies on materials engineering. This paper shows principle of neutron stress measurement and engineering neutron diffractometers as well as some applications.
Utilizing the neutron magnetic scattering, one can investigate magnetic materials by looking at their magnetic nano structures. It is not exaggerated to state that nearly all the present microscopic knowledge of solid state magnetism has been obtained by neutron magnetic scattering experiments in the steady state neutron beam facilities at research reactors. In this review, we would like to introduce basics of the neutron magnetic scattering and demonstrate its strength by presenting some recent experiments on magnetic materials performed at the Research Reactor JRR-3 facility in the Nuclear Science Research Center, Tokai, Japan Atomic Energy Agency. The operation of the pulsed neutron source facility in the Materials and Life Science Facility of Japan Proton Accelerator Complex (J-PARC) will make the magnetic neutron scattering techniques even more common place, and the complementary use of both the steady state and pulsed neutron facilities in the near proximity will serve the broad users from academia and industries investigating magnetic materials.
Fine structures in ceramics are important for enhancing the electrical, thermal, optical and mechanical properties of ceramics. Magnetic field alignment of the crystal orientations of fine particles is one of the most effective methods for controlling fine structures. We used neutron diffraction to investigate magnetic alignment of α-Al2O3 fine particles. In situ neutron diffraction measurements of the suspension were performed to investigate the effect of applying a magnetic field. The results revealed that the balance between the magnetic anisotropy energy and thermal fluctuations is critical in determining the crystal orientations of the α-Al2O3 particles in the suspension. Samples were produced by systematically varying the sintering temperature. They were used for neutron diffraction measurements to investigate the effect of sintering. We found that the crystal orientation improves dramatically at temperatures above the grain growth temperature. In this review, we present the experimental details of the neutron diffraction measurements and analyze the results.
We review recent progress of neutron scattering studies on soft matters using various techniques such as small angle neutron scattering, neutron spin echo, backscattering, time-of-flight technique, reflectivity and grazing-incident small angle neutron scattering. In the present review, we focus on functionalized polymers such as polyrotaxane, Nafion, polymer/nano composite system, and casein protein thin films, which are of great interest from both scientific and industrial viewpoints. We also state some future experiments at J-PARC.
Due to a high-flux of pulsed neutron beam served at J-PARC, a new world of biological science will be opened in a very wide hierarchal structure and dynamics that are essential in biological phenomena. In this short review, our recent studies of 'lipid rafts' model membrane using small-angle neutron scattering and neutron spin echo are introduced. 'Lipid rafts' have been attracting great interest since they are assumed to have a function as a platform of membrane-associated events such as signal transduction, cell adhesion, lipid/protein sorting and so on. In this decade knowledge about their biological functions have been accumulated intensively. Lipid rafts are considered as a dynamic assembly of lipids (major components are sphingolipid and cholesterol) and proteins. However, their structure and dynamics in plasma membrane still remain the subject of debate. We have clarified prominent characteristics of lipid-raft model membrane composed of glycoshpingolipid (ganglioside)/cholesterol/phospholipid.
Neutron reflectivity is a feasible probe for surfaces and interfaces. It can provide information on the density, layer thickness and roughness for multilayered thin films. As it does not always require vacuum, one could study the variety of real surfaces and interfaces under the controlled atmosphere. The technique has some common features to X-ray reflectivity, but at the same time it owns very unique and extremely attractive features, such as high-sensitivity to low Z elements including isotope effects in soft materials and availability for magnetic structure analysis. The present article describes the recent activities of currently accessible neutron reflectometers in Japan.
J-PARC Materials Life Science Facility (MLF) is an 1 MW spallation neutron source. It has been operating for user programmes since 2008. MLF accommodates various scientific fields ranging from physics, chemistry, polymer science, bio-crystalography, to material sciences. Now large number of experimental proposals have been already submitted not only from university researchers but also from industries. The neutronic performance is expected to be one of the world best on achieving 1 MW. Therefore it is strongly anticipated to be a world research center in the near future.
A big neutron facility has been installed at J-PARC in Japan based on a high power proton accelerator. Neutrons are delivered in the pulsed nature. This pulsed nature allows us to develop a new frontier in the neutron radiography field. It is very easy to obtain wavelength dependent images by using the time-of-flight energy-analysis method combined with the pulsed nature. The imaging data depending on the wavelength includes the information on the neutron reaction cross section which reflects the micro structure of the object and the characteristic absorption of the elements. Therefore, we can deduce the micro structure information as well as the element information of the object. For example, spatial distributions of preferred orientation, crystallite size, and strain are obtained. Furthermore, as one of the special applications of the neutron imaging, magnetic field is also obtained. Here, the recent progress of this method is introduced.
The c-BN (cubic boron nitride) has a property of very high hardness and very low friction. Therefore, the application for cutting tool had studied during many enterprises for long time. But they hadn't gotten strong adhesive thin films to the substrates. The c-BN thin films were prepared by magnetically enhanced plasma ion plating (MEP-IP). These thin films were inserted the intermediate layers and were prepared functionally gradient BN films. The results were gotten very strong adhesion to the substrates. The gained properties of the thin films were the hardness of about 5,400 HK (Knoop hardness) and the friction coefficient of about 0.12. That rate of the deposition was 0.7 µm/h.
The generation of radial gas flow by rotating a set of screens radiating in all directions while also rotating a combination of radial screens and disks perpendicular to the axis was investigated by Monte Carlo simulation. The results were as follows: a) Radial flow is effectively enhanced by rotating the set of screens with a velocity ratio rω/<υ> of greater than 2, where <υ> is the mean velocity of the gas molecules and rω is an additional circumferential velocity due to rotation. Moreover, the compression ratio becomes greater than 106 when the velocity ratio is greater than 3. b) The special combination of parallel disks and radial screens has both a large pumping efficiency greater than 0.5 and a large compression ratio greater than 105 with a velocity ratio of 3.