Multiple-wavelength neutron holography with pulsed neutrons

Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the x-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similarmethod using neutron techniques has not yet been developed. If one can establish amethod of local structural analysis with neutrons, then a new frontier ofmaterials science can be explored owing to the specific nature of neutron scattering-that is, its high sensitivity to light elements andmagneticmoments. Multiple-wavelength neutron holography using the time-of-flight technique with pulsed neutrons has great potential to realize this. We demonstrated multiple-wavelength neutron holography using a Eu-doped CaF₂ single crystal and obtained a clear three-dimensional atomic image around trivalent Eu substituted for divalent Ca, revealing an interesting feature of the local structure that allows it tomaintain charge neutrality. The newholography technique is expected to provide new information on local structures using the neutron technique.