An electron microscope image (left) and a schematic image (right) of the newly-created LaPt5As crystal.
An electron microscope image (left) and a schematic image (right) of the newly-created LaPt5As crystal.

Superconductors are materials that, when cooled below a certain temperature, allow electricity to travel through them without any resistance. They are used in magnetic resonance imaging (MRI) machines, magnetic levitation trains and particle accelerators like the Large Hadron Collider. Researchers are constantly on the lookout for inexpensive new materials that can become superconducting at higher temperatures than currently possible.

A team of researchers from Hokkaido University, along with colleagues at the Kyushu Institute of Technology, NEC Corporation, Keio University and the National Institute for Materials Science, have now developed a novel superconducting material based on platinum. They have managed to do this even though until recently platinum was not thought to have superconducting properties.

As the researchers report in a paper in the Journal of the American Chemical Society, they developed the novel material by mixing lanthanum (La), platinum (Pt) and arsenic (As) powders in a ratio of 1:5:1. They then compressed this mixture into pellets and heated them to 500°C for 10 hours. The resultant material was ground up and re-pelletized, then heated at 1000°C for an hour at various pressures. At a pressure of 5GPa (gigapascals) – equivalent to 50,000 bars of pressure – this process produced a non-superconducting form of LaPt5As, but at 10GPa it produced a superconducting form, with another non-superconducting form at 15GPa.

The researchers examined the crystal structure of the superconducting form of LaPt5As. This revealed that the platinum atoms arranged themselves into multiple layers in the material, with these layers piling up as high as 6nm, the highest among metal superconductors. They also found that the lanthanum and arsenic atoms separated the platinum layers from each other. The researchers speculate that this structure weakens the interaction between the platinum electrons, allowing them to flow more freely and giving rise to the superconducting property.

Future research that determines the detailed crystal structure of the non-superconducting forms of LaPt5As should help to reveal the mechanism that causes the material to become superconducting at 10GPa, the researchers say.

High-pressure synthesis (over 10GPa) is not a commonly-used method in the field of materials science. According to the researchers, this study thus shows there is room for further exploration of unknown phases induced by high pressure in a variety of materials.

This story is adapted from material from Hokkaido University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.