A new twist on polyhydrides may hold the answer to achieving room-temperature superconductivity

A new study looks at how can we achieve superconductivity at room temperature and normal pressures.
Tejasri Gururaj
Superconductivity representation


Superconductors are materials that can conduct electricity by offering zero resistance. Room temperature superconductors are one of the great curiosities in modern engineering and physics, and great strides have been made in this area of research. Once realized, room-temperature superconductors could have a wide range of applications, such as high-efficiency power grids, magnetically levitation vehicles, affordable and compact MRI scanners, and powerful quantum technologies.

A team of scientists from the Skolkovo Institute of Science and Technology, the Center for High-Pressure Science and Technology Advanced Research (HPSTAR), and Jilin University has made a significant breakthrough by successfully synthesizing a lanthanum-cerium polyhydride, potentially revolutionizing the field of superconducting research.

Generally, superconductors require very low temperatures and high pressures to exhibit zero electrical resistance. However, the study published in Nature Communications showed that the polyhydride was able to exhibit superconductivity at 176 K (approximately -143 Fahrenheit) and 1 million atmospheres, surpassing the previous benchmark of -9 Fahrenheit (-23 Celcius) and 1.5 million atmospheres shown by lanthanum hydride (LaH10).

What are polyhydrides?

Lanthanum hydride belongs to a class of compounds known as polyhydrides. These compounds contain an unusually large number of hydrogen atoms bonded to other elements, such as lanthanum and sulfur.

Polyhydrides, which form under high-pressure conditions, have garnered considerable interest in superconductivity research due to their ability to exhibit superconductivity at comparatively higher temperatures than conventional superconductors.

Superconducting material at room temperature and pressure

To bring down the pressure requirements of the lanthanum hydride, the researchers decided to mix things up by introducing cerium, which is very similar to the lanthanum atom. Cerium hydrides (CeH10 and CeH9) have exhibited superconducting properties in previous studies, which is why the researchers thought its addition would work.

A new twist on polyhydrides may hold the answer to achieving room-temperature superconductivity
La-Ce-H compound for superconducting material

This was realized by heating a lanthanum-cerium alloy in a high-pressure cell containing ammonia borane, a compound that releases an abundant amount of hydrogen during decomposition.

The addition of the cerium alters the structure of pure LaH10 and improves its stability. They found that the resulting La-Ce-H compound exhibited superconductivity at the same pressure (1 million atmospheres) as cerium polyhydrides. But those show superconductivity at temperatures below -252 Fahrenheit (-158 Celcius), whereas the researchers' La-Ce-H compound showed at a temperature of -143 Fahrenheit (-97 Celcius), so they got the best of both worlds by using lanthanum and cerium.

Furthermore, the study uncovered intriguing similarities with cuprates, a class of materials known for their superconductivity at temperatures below -220 Fahrenheit (-140 Celcius), even at normal atmospheric pressure. 

This finding is a significant step in the development of room-temperature semiconductors at reasonable pressures, opening up new possibilities in physics and engineering!

The study was published in Nature Communications.

Study abstract:

Ternary hydrides are regarded as an important platform for exploring high-temperature superconductivity at relatively low pressures. Here, we successfully synthesized the hcp-(La, Ce)H9-10 at 113 GPa with the initial La/Ce ratio close to 3:1. The high-temperature superconductivity was strikingly observed at 176 K and 100 GPa with the extrapolated upper critical field Hc2(0) reaching 235 T. We also studied the binary La-H system for comparison, which exhibited a Tc of 103 K at 78 GPa. The Tc and Hc2(0) of the La-Ce-H are respectively enhanced by over 80 K and 100 T with respect to the binary La-H and Ce-H components. The experimental results and theoretical calculations indicate that the formation of the solid solution contributes not only to enhanced stability but also to superior superconducting properties. These results show how better superconductors can be engineered in the new hydrides by large addition of alloy-forming elements.

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