Northwestern University researchers 3D print more powerful YBCO superconductors

Superconductor materials made of ceramics have shown a frustrating downside to more advanced superconductors: their ceramic property makes them brittle. David Dunand, professor of materials science and engineering at the McCormick School of Engineering and collaborators from Fermilab are out to change this with the help of a ceramic paste material extrusion (MEX) 3D printing process. Their printing method printed YBCO superconductors that will have more power, which will help superconductor-powered inventions cost less.

“Ceramic-based cuprates are common high-temperature superconductors, and, because they operate with liquid nitrogen, are immensely cheaper and easier to work with than low-temperature metal superconductors,” said Dunand. “The shapes these materials can make have been limited because of their brittleness. You’d like to be able to make complex objects that are optimized for energy efficiency.”

The team’s work is outlined in the paper “Additively-manufactured Monocrystalline YBCO Superconductor,” published Feb. 24 in Nature Communications. Dunand was a co-corresponding paper author along with Dingchang Zhang (PhD ’24), a postdoctoral researcher at the University of California, Berkeley, and a former student in Dunand’s lab. Cristian Boffo, PIP-II project manager at Fermilab, also co-authored the study.

To avoid being limited by cuprates’ brittleness, the research team developed a method to successfully produce single-crystal YBCO—an ordinary polycrystal superconductor—using additive manufacturing. Yttrium barium copper oxide (YBCO) is a family of crystalline chemical compounds with high-temperature superconductivity; it includes the first material ever discovered to become superconducting above the boiling point of liquid nitrogen.

Breaking down the process, the first step uses commercially available precursor powder to prepare ink. Ink is then put in the syringe to create YBCO micro-lattices or other complex geometries that are polycrystals. The 3D printed material becomes a single crystal on 3D printed parts by a melt growth method.

Usually, bulk superconductors are created in a simple form by mold pressing. They are then sintered or heated, and the pressed powders merge. The researchers used ink (paste) containing YBCO powder and applied it via 3D printing to create a complex object for sintering.

The researchers were also able to remove the material’s grain boundaries, which are small defects in crystal structures that can lessen a material’s electrical and thermal conductivity. This resulted in a more effective superconducting current.

“People have made single crystals in a block of material, and we’ve shown we can use this same technique with 3D printing,” Zhang said. “During our process, we can fabricate complex shapes, such as toroidal coils, with a single crystal seed placed on top. These 3D printed parts partially melt through a controlled processing window and transform into single crystals, retaining their original 3D printed shape.”

“At Fermilab, we are developing the next-generation superconducting magnets that will drive scientific experiments for decades to come,” Boffo said. “The technology created through this collaboration will enable previously unimaginable designs, thereby enhancing our potential for advancement.”

“The single-crystal object can carry a greater amount of electrical current, making it able to provide more power, thus making magnets immensely stronger,” Dunand said. “This provides more energy for particle accelerators, such as FermiLab. The faster particles may unlock discoveries for physicists.”

According to Dunand, this work has the potential to be only the beginning of more powerful and efficient superconductors. The group plans to apply its method to other ceramic superconductor materials.

“We conducted this research with YBCO, the most common superconductor, but there are many other compounds with even higher performance temperatures than can be processed by our method,” Dunand said. “The possible applications for this are very exciting.”