Discovery of La(Fe,Si)13-based magnetocaloric materials and study on related scientific problems

Abstract

Refrigeration technique based on magnetocaloric effect has obvious advantage over the conventional gas-compression technique in environment protection and energy conservation, and the economic and social benefit from its application is immeasurable. Refrigerants with strong magnetocaloric effect are the keys for magnetic cooling and have long been a goal of material exploration. After systematic investigations on the structural and magnetic properties of rare earth-transition intermetallics, Prof. Baogen Shen, Fengxia Hu, Jirong Sun, et al. successfully discovered a new kind of materials, LaFeSi-based intermetallics with low Si content and first-order transition, which show entropy changes twice as large as that of the rare-earth metal Gd. Their studies revealed that the giant magnetocaloric effect originates from lattice contraction and itinerant electron metamagnetic transition. Based on both theoretical and experimental investigations, they proved that the Maxwell relation, which is commonly adopted to determine magnetic entropy change, cannot be directly applied in the case of first-order phase transition, and established an appropriate method determining entropy change for phase-separated systems. This work clarified the confusion due to the false reports on colossal MCE in the academic journals such as Nat. Mater., Phys. Rev. Lett. and etc.. The discovery of LaFeSi-based magnetocaloric materials provides theoretical and technological supports to magnetic refrigeration, and will significantly push forwards the practical application of magnetic refrigeration technology.
 
Shen Bao-gen was born in September 1952. He graduated from the University of Science and Technology of China in 1976. Since then he has been working at the Institute of Physics, Chinese Academy of Sciences (CAS) successively as assistant research scientist, associate professor and professor in physics. He received the Alexander von Humboldt Fellowship, studying the structure and magnetic properties of rapidly quenched rare-earth-iron alloys at the Ruhr University, Germany, as a visiting scholar during 1986-1988. He was former vice-secretary general, CAS and deputy-director of Institute of Physics, CAS. Now He is the director of the State Key Laboratory for Magnetism and the deputy chairmen of Academic Council, Institute of Physics, CAS. He also is the Chairman of Magnetism Division, Chinese Physical Society, and the Associate Editor of Chinese Physics B, Acta Physica Sinica and Rare Metals. He was elected member of CAS in 2011 and fellow of TWAS in 2013.

For over 30 years, Prof. Shen has been mainly engaged in research on the magnetism and magnetic materials. He has co-authored 395 papers and 35 patents. He has completed supervision of 33 Ph.D. theses, 2 M.Sc. theses, and 10 post-doctoral fellows. He received the National Outstanding Youth Science Foundation in 1995. His prizes include the 2nd Class of the National Natural Science Awards of China; the 1st class of the S&T Awards of Beijing twice; Distinguished Young Research Awards, Qiu Shi S&T Foundation, Hong Kong; Ye Qi-Sun Physics Awards, Chinese Physical Society and the S&T Awards, the Ho Leung Ho Lee Foundation, Hong Kong. 
 
Prof. Feng-Xia Hu was born in September, 1965, Hebei Province. She received B.S. degree from Hebei normal University in 1985 and Ph.D. degree from Institute of Physics, Chinese Academy of Sciences (CAS) in 2002. From 2000 to 2002 she worked as a postdoctoral research fellow in physics department, the University of Hong Kong. Currently she is working as a full professor and a group leader in Institute of Physics, CAS. Her research field is experimental condensed matter physics. Her recent works include structure, magnetic property and magnetocaloric effect of intermetallics, interface and transport properties of heterojunctions composed of oxides. Since 2000, Prof. Hu has authored or coauthored more than 120 papers which were citied over 2700 times. Her research achievements have won the second prize of the National Natural Science Award of China in 2012, and the first prize of the Science and Technology Award of Beijing in 2010.
 
Jirong Sun, Professor of the Institute of Physics of the Chinese Academy of Sciences. He was born in Heilongjiang Province in October of 1957. He received his bachelor's degree in 1982 from the Department of Physics of Jilin University, his Ph. D. degree in 1989 from the Chinese Academy of Sciences, and was promoted to professor in November of 1999. He has undertaken a series of state key projects from the Ministry of Science and Technology of China and the National Nature Science Foundation of China, participated in the discovery of the magnetic materials with giant magneto-caloric effect, the solution of the fundmental problems involved in this kind of magnetic materials. He also revealed the relationship between the novel properties of complex oxides and electronic/magnetic phase separation. He has published more than 320 papers in famous international academic journals, and his works have been cited more than 3500 times. He received the National Outstanding Youth Science Foundation in 2002. He won, together with his colleagues, the first prize of science and technology of Beijing one time and the second prize of National Natural Science one time.