Researchers at the University of Tokyo in Sofia have mixed and designed a new high-entropy alloy (HEA) superconductor using extensive data on simple superconducting substances with a specific crystal structure. HEAs are known to retain superconducting characteristics up to extremely high pressures. The new superconductor, Co.0.2Ni0.1C0.1Rh0.3Ir0.3Zr2, has a superconducting transition at 8K, a relatively high temperature for HEA. The team approach can be applied to discover new superconducting materials with specific desired properties.
More than a hundred years have passed since the discovery of superconductivity, where it was found that some materials suddenly show minimal resistance to electric currents below the transition temperature. As we explore ways to eliminate energy loss, how to drastically reduce energy transmission losses is a fascinating prospect. But the widespread use of superconductivity is hampered by the requirements of existing superconductors, especially the necessary low temperatures. Scientists need a way to discover new superconducting materials without brute force through trial and error and to adjust key properties.
A team led by Associate Professor Yoshikazu Mizuguchi of the University of Tokyo is a pioneer in the “discovery platform”, which has already led to the design of many new superconducting substances. Their method is based on high entropy alloys (HEA), where certain places in simple crystal structures can be occupied by five or more elements. After their application on heat-resistant materials and medical devices, it was found that some HEAs have superconducting properties with some exceptional characteristics, especially maintaining zero resistance at extreme pressures. The team researches databases with materials and modern research and finds a set of superconducting materials with a common crystal structure, but different elements of specific objects. They then mix and design a structure that contains many of these elements; throughout the crystal, these “HEA sites” are occupied by one of the mixed elements (see Figure 1). They have already succeeded in creating high entropy variants of layered bismuth sulfide superconductors and telluride compounds with a crystalline structure of sodium chloride.
In their latest work, they focused on copper alumide (CuAl2) structure. Compounds combining a transition metal element (Tr) and zirconium (Zr) in TrZr2 with this structure it is known to be superconducting, where Tr may be Sc, Fe, Co, Ni, Cu, Ga, Rh, Pd, Ta or Ir. The team combines a “cocktail” of these elements using arc melting to create a new HEA, Co0.2Ni0.1C0.1Rh0.3Ir0.3Zr2which showed superconducting properties. They examined both the resistance and the specific electron heat, the amount of energy used by the electrons in the temperature-raising material, and identified a transition temperature of 8.0K. Not only is this relatively high for HEA-type superconductors, they confirmed that the material has the hallmarks of “bulk” superconductivity.
The most exciting aspect of this is the wide range of other transition metals and ratios that can be tested and tuned to strive for higher transition temperatures and other desired properties, all without changing the underlying crystal structure. The team hopes their success will lead to more discoveries of new HEA-type superconductors in the near future.
Fabrication of new layered superconductors using high entropy alloys
Yoshikazu Mizuguchi et al, Superconductivity in CuAl2-type Co0.2Ni0.1C0.1Rh0.3Ir0.3Zr2 with a high entropy transition metal site, Letters for research materials (2020). DOI: 10.1080 / 21663831.2020.1860147
Provided by Tokyo Metropolitan University
Quote: The transitional metal “cocktail” helps to make brand new superconductors (2021, January 11), extracted on January 12, 2021 from https://phys.org/news/2021-01-transition-metal-cocktail-brand-superconductors. html
This document is subject to copyright. Except for any fair transaction for the purpose of private examination or research, no part may be reproduced without written permission. The content is provided for informational purposes only.