Neutrons open the window to explore space glass

Thanks to human ingenuity and weightlessness, we are reaping important benefits from space science. Consider smartphones with built-in navigation systems and cameras.

Such transformational technologies seem to become integrated into the rhythm of our daily lives overnight. But they are born from years of discoveries and developments of materials that can withstand harsh environments outside of our atmosphere. They result from decades of foundation in fundamental science to understand how atoms behave in different materials and under different conditions.

Building on this past, a global team of researchers has set a new benchmark for future materials manufacturing experiments in space rather than for space. The team included members of the Department of Energy’s Oak Ridge and Argonne National Laboratories, Materials Development, Inc., NASA, Japan Aerospace Exploration Agency or JAXA, ISIS Neutron and Muon Source, from Alfred University and the University of New Mexico. Together, they discovered that many types of glass, including those that could be developed for next-generation optical devices, have similar structure and atomic arrangements and can be successfully manufactured in space.

The team’s article is published in the journal npj Microgravity.

“The idea is to test the mechanisms behind space manufacturing, which can lead to materials that are not necessarily available on Earth,” said Jörg Neuefeind, who joined ORNL in 2004 to build an instrument called NOMAD to the laboratory’s spallation neutron source. (SNS). NOMAD, the world’s fastest neutron diffractometer, helps scientists measure the arrangement of atoms by observing how neutrons bounce off them. NOMAD is one of 20 SNS instruments that help scientists answer big questions and spur countless innovations, such as drugs that treat disease more effectively, more reliable airplane and rocket engines, cars with better gas mileage and safer batteries that charge faster and last longer. .

JAXA operators on Earth made and melted glass aboard the International Space Station (ISS), via remote control using a levitator. Levitations are used to suspend material samples during experiments to avoid interference from contact with other materials.

Once the next ISS mission ended months later and the space glass was returned to Earth, researchers used a combination of techniques including neutrons, X-rays and powerful microscopes to measure and compare the fabricated and melted glass celestially compared to that of the Earth.

“We found that with container-free techniques, such as levitator, we can create unconventional glasses in microgravity,” said JAXA’s Takehiko Ishikawa, who pioneered the electrostatic levitator used to make the glass beads aboard the ISS.

The researchers relied on NOMAD at SNS to study the glass samples with neutrons and on the beamlines of the Argonne Advanced Photon Source to study the samples with X-rays. Both SNS and APS are facilities DOE Office of Science user.

“There’s only so much material you can fly into space and back, and that’s actually one of the reasons NOMAD was so well suited for this experiment,” said Stephen Wilke of Materials Development Inc. and a visiting scientist at Argonne. . “We were only recovering single glass beads about an eighth of an inch in diameter, which are very difficult to measure in terms of atomic structure. Since NOMAD excels at measuring extremely small samples, this allowed us to compare easily the unique beads we made in the lab with those made on the space station.

Mysteries of glass

Turns out the glass isn’t as sharp. Unlike crystalline solids like salt, glass atoms do not have a uniform structure. Its unusual atomic arrangement, although remarkably stable, is perhaps best described as a random network of molecules sharing coordinated atoms. Neither entirely solid nor entirely liquid, glass also comes in different forms, including polymer, oxide, and metallic, such as in spectacle lenses, fiber optic threads, and hardware for deep space missions.

In 2022, Neuefeind, Wilke and Rick Weber, a glass industry expert, experimented with two oxides of neodymium and titanium and discovered potential for optical applications. The combination of these two elements presents unusual advantages not found in similar search campaigns. These discoveries led them to continue their current studies with NASA.

“(The experiment conducted in 2022) taught us something truly remarkable,” said Weber, of Materials Development Inc. “One of the glasses has a completely different lattice than a normal four-coordinate lattice typical of the silica. These glasses have a six-coordinate network. They’re really out there. It’s exciting from a glass science perspective, but from a practical perspective it also means more. opportunities to do new things with optical materials and new types of devices.

Scientists often use neutrons and X-rays in parallel to collect data that no other technique can produce, allowing us to understand the arrangement of atoms of different elements within a sample. Neutrons helped the team see lighter elements in space glass, like oxygen, while X-rays helped them see heavier elements, like neodymium and titanium. If significant differences existed between space glass and terrestrial glass, they would likely have manifested themselves in the oxide sublattice, or in the arrangement of oxygen atoms, in the distribution of heavy atoms, or in both.

Neutrons will become increasingly important tools for unlocking the mysteries of matter as scientists explore new frontiers, despite space.

“We need to understand not only the effects of space on matter, but also its effects on how things form,” Neuefeind said. “Because of their unique properties, neutrons help solve these kinds of puzzles.”