Application of precise neutron focusing mirrors for neutron reflectometry: latest results and future prospects

Abstract

Neutron reflectometry (NR) is a powerful tool for providing insight into the evolution of interfacial structures, for example via operando measurements for electrode–electrolyte interfaces, with a spatial resolution of nanometres. The time resolution of NR, which ranges from seconds to minutes depending on the reflection intensity, unfortunately remains low, particularly for small samples made of state-of-the-art materials even with the latest neutron reflectometers. To overcome this problem, a large-area focusing supermirror manufactured with ultra-precision machining has been employed to enhance the neutron flux at the sample, and a gain of approximately 100% in the neutron flux was achieved. Using this mirror, a reflectivity measurement was performed on a thin cathode film on an SrTiO3 substrate in contact with an electrolyte with a small area of 15 × 15 mm. The reflectivity data obtained with the focusing mirror were consistent with those without the mirror, but the acquisition time was shortened to half that of the original, which is an important milestone for rapid measurements with a limited reciprocal space. Furthermore, a method for further upgrades that will reveal the structural evolution with a wide reciprocal space is proposed, by applying this mirror for multi-incident-angle neutron reflectometry.

Progress in neutron techniques: towards improved polymer electrolyte membranes for energy devices

“…flooding), while being effective in resisting damage caused by fuel impurities [135]. Under low-RH conditions, changes in membrane properties (porosity, hydrophobicity, thickness) necessitate careful characterisation of the structure under operando conditions [136] in order to minimize Ohmic drop while managing the water content for optimal performance. Improvements in reflectivity instruments (e.g., RAINBOWS at ILL [72]) are set to open up new possibilities for operando studies of thin-film AEM membranes, while highlighting the evolution of interfacial structures, as has been demonstrated for electrode-electrolyte interfaces [135].…”

Effect of the nitrogen content of sputtering gas during Ni deposition on Ni/Ti periodic multilayers and neutron supermirror performance

“…Researchers from RIKEN conducted amorphous nickel-phosphorus (Ni-P) plating, diamond cutting and polishing on the substrate surface, and coated supermirrors on the substrate. Consequently, they fabricated two-segment elliptical focusing supermirrors, which enhanced the illumination of small samples and increased the beam time efficiency (Takeda et al, 2016;Hosobata et al, 2017Hosobata et al, , 2019Yamada et al, 2020). Herb et al (2022) designed a prototype elliptic nested mirror optics coated with m = 4.1 polarized supermirrors, which demonstrated a high imaging figure of merit of 72%.…”

Crystallization and Composition of Ni-C/Ti Multilayer with Varied Ni-C Thickness

“…Maruyama et al fabricated Ni-C/Ti supermirrors with m = 3, m = 4, and m = 6.7 by ion beam sputtering, and they demonstrated that doping carbon atoms to the Ni layer suppressed the interface roughness and led to higher reflectivity than when using Ni/Ti supermirrors [4]. The neutron-focusing supermirrors deposited on the ultra-precision figured substrates were fabricated and proved to be effective [5][6][7]. The measured efficiency and signal-to-noise ratio during the process were dominated by neutron flux for the focusing devices, and the neutron flux was related to the value of m of neutron supermirrors, which is the central component of the focusing devices.…”