I. Research progress of materials:
In the late 19th century, with the development of low-temperature technology, scientists noticed the phenomenon that the electrical resistance of pure metals decreases with the decrease of temperature. 1911, the Dutch physicist Camorin. Onnes (H. Karmerligh-onnes) in Leiden (Leiden) laboratory research at very low temperatures in a variety of metal resistance changes, the first discovery of mercury (Hg) in 4.2K when the resistance of the phenomenon suddenly zero (known as superconductivity), opened the prelude to superconductivity research. Onnes was awarded the 1913 Nobel Prize in Physics for liquefying helium in 1980 and for his research on superconductivity in 1911. Since then, scientists have discovered and produced thousands of superconducting materials after more than seventy years of efforts until the beginning of 1986, and at the same time, they have increased the critical temperature of superconducting materials made of metals and their alloys, Tc (the temperature at which superconductivity occurs), from 4.2 K to 23.2 K. (The NB3Ge compound with a Tc of 23.2 K, discovered in 1973, held the record of the highest critical temperature until 1985). Critical temperature record), an average of only 0.253K progress per year, but in 1986 a breakthrough occurred. In January 1986, IBM Zurich laboratory of the German J.G. Bednorz Swiss K.A. Muler announced the discovery of lanthanum-barium-copper oxide superconductors may reach Tc = 35K, thus the world, the The discovery of lanthanide-barium-copper oxide superconductors with a Tc=35K immediately set off a wave of exploration of superconducting materials, and the two were awarded the 1987 Nobel Prize in Physics for their discovery of high-temperature superconductors. Since then, in the high critical temperature superconductor research faster, made a series of breakthroughs, the United States, Japan and many other countries in the development of high-temperature superconductivity has also made excellent contributions.