Functional materials

Multilayer Neutron Optics Based on Isotope-Enriched ¹¹B₄C

PhD: Sjoerd Stendahl (Broekhuijsen), Linköping University (2023)

This project explored the development of high-performance neutron optical multilayers based on isotope-enriched ¹¹BC for use in neutron mirrors and supermirrors. Through ion-assisted magnetron sputtering and co-deposition techniques, the research achieved smoother and more abrupt interfaces, which are crucial for enhancing neutron reflectivity.

A combination of neutron reflectometry, X-ray reflectivity, transmission electron microscopy, and grazing incidence small-angle scattering (GISAXS) was used to characterize interface structure, roughness, and morphology. The incorporation of ¹¹B₄C led to significant improvements in interface sharpness—down to 2.7 Å—and enabled a predicted reflectivity increase of over 500% compared with conventional Ni/Ti multilayers.

By demonstrating isotope-engineered ¹¹B/¹⁰B interference mirrors and hybrid multilayer designs, the research opened new directions for next-generation neutron optics, contributing to more efficient and precise neutron scattering instrumentation.

Sjoerd Stendahl (Broekhuijsen) is originally from the Netherlands and obtained a BSc in Applied Physics in 2015 and an MSc in Material Physics from the University of Twente. During his master’s studies, he carried out research at Linköping University in the Thin Film Physics group, where he studied changes in sugar composition in soft drinks using Mueller matrix ellipsometry. His master’s thesis focused on the growth and optical characterisation of InAlN thin films grown by reactive sputtering, with structural analysis performed using XRD.