AWARDEE OF PHYSICS PRIZE

YANG YINGCHANG

Yang Yingchang, physicist. He was born in 1934 in Beijing. He has been a faculty member at Peking University since he graduated from the Physics Department of Peking University in 1958. He was elected academician of the Chinese Academy of Sciences in 1997. Currentely, he is a professor at the School of Physics, Peking University.
His major research interest is in the field of magnetism. He studies the correlation between macroscopic magnetic properties and microscopic structures of magnetic matter. To explore the potential of Chinas abundant resources of rare earth, special emphasis has been put on the study of magnetism of 4f electrons related to the rare earth metals and 3d electrons of transition metals. Along this vein, novel magnetic materials have been investigated and invented. His major achievements are as follows:
(1)In search of Cobalt-free magntic materials, he spearheaded research on the intermetallic compounds based on rare earth-iron when the rare earth–Co magnets were dominant in the 1970s. He was the first to synthesize a new phase rich in iron with the ThMn12 type structure, and to determine its structural characteristics and formation factors by neutron diffraction studies in 1980. Now an important series of rare earth alloys has been developed based on the phase his discovered.
(2) There are 6 nonequivalent crystallographic sites for Fe in Nd2Fe14B. He made a systematic substitution study to investigate the magnetic properties of Fe on the individual site by using neutron diffraction, Mossbauer effect and high temperature X-ray diffraction techniques. Based on this study, he developed multicomponent magnets of Nd2(Fe、Al、Co)14B with enhanced coercive force and Curie temperature, which allows the magnets to be used in a lager temperature range.
(3) He and his colleagues discovered interstitial nitrogen atom effect on the rare earthiron intermetallics in 1990. As a result they found the novel hard magnetic materials of Nd(Fe,M)12Nx and Pr(Fe,M)12Nx, where M is Ti,V,Mn,Mo ...(The abbreviation is Nd-Fe-N or Pr-Fe-N respectively). They were the first to determine the crystallographic structure of these nitrides by using neutron diffraction study, and elucidated the origin of the interstitial effect by calculating the change in crystal field interaction and electronic structure before and after nitrogenation. Based on a systematic study of the domain structure and the demagnetization mechanism of Nd-Fe-N, they have developed a new process to manufacture high performance magnetic powders based on Nd-Fe-N for commercial use.
He was awarded the Natural Science Prize，Second class in 1991 and 2003, the First Prize for Science and Technology Progress of National Education Committee in 1991 and 1993, Wang Danping Prize for Science in 1992, and Prize for National Excellent Doctoral Thesis Advisor in 2000.