Using Rare Earth Substitution to Prepare Iron-Based Compounds Accelerates Superconductivity Research

Using rare earth substitution method to prepare iron-based compounds has been used in superconductivity research. The iron-based superconductors are superconducting hybrid materials in which iron elements play a leading role. Iron-based superconductors are the second high-temperature superconducting system of concern after copper-based superconductors. The research on it is the hottest field of superconducting physics and China has played a key role in the development of this field globally.

Superconductivity, a clear-cut quantum phenomenon of zero electrical resistivity and perfect diamagnetism, was discovered in 1911 for mercury. If materials with superconducting properties are found at room temperature, the technology of current utilization will leap. In the traditional theoretical framework, the critical temperature of a metal superconductor has a theoretical upper limit of 40K, called the McMillan limit, and the room temperature is usually 300K, which is so large that it cannot be bridged, later, the discovery of iron-based superconductors making the high-temperature superconductors becomes possible.

In 2008, researchers at the Chinese Academy of Sciences and the University of Science and Technology of China have sensitively captured the superconductivity in iron-containing compounds. Chinese scientists have quickly used a rare earth substitution method to prepare a series of iron-based compounds. On March 28, 2008, a group led by Zhongxian Zhao, one of the founders of the research, reported that the high-temperature superconducting critical temperature of fluorine-doped praseodymium-oxygen arsenic compounds can reach 52K, and soon they found 55K iron-based superconducting materials - another high-temperature superconducting family beyond the limits of McMillan was discovered, the breakthrough shocked the international academic area.

In the following years, Chinese scientists discovered a large number of iron-based materials. The discovery of iron-based high-temperature superconductors has injected a shot of cardiac stimulant into the superconducting research for many years. Compared with copper-based superconductors, iron-based superconductors possess abundant physical properties and potential application value, which leads people to discover the mechanism of high-temperature superconductivity.

A series of iron-based compounds were prepared by rare earth replacement method has accelerated the step of China to become the frontrunner in superconductivity research as well as superconducting applications of the world. For example, the “man-made small sun” in Hefei, the superconducting Tokmak device EAST, once again created a record of controllable nuclear fusion experiments to achieve an electronic temperature of 100 million degrees Celsius plasma operation. Also, China owns the world's advanced superconducting maglev train technology.

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