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Zheng wins Materials Research Society best poster

Yuanhua Zheng, graduate fellow and graduate research associate in The Ohio State University’s Thermal Materials Laboratory, won best poster at the Materials Research Society fall meeting in Boston, Massachusetts held from November 27 – December 2, 2016.  Zheng is advised by Professor and Ohio Eminent Scholar Joseph Heremans.

Posters from around the world were presented at the conference which hosts cross-disciplinary worldwide activity in materials research, featuring over 50 symposia and attended by as many as 6,000 researchers from every corner of the globe.  It is the preeminent annual event for those in the field of materials research.

Zheng did his undergraduate work at Tsinghua University, China and joined Professor Heremans’ group in the Thermal Materials Lab in 2015. His research is focused on Fe-Co alloys as thermoelectric materials, which was also the topic of his winning poster. 

Yuanhua Zheng (second from left) with his winning poster at the Materials Research Society fall meeting in Boston, Massachusetts

“Yunahua's poster describes the design of iron-cobalt alloys in which the thermal fluctuations of the magnetic moments on the iron atoms are used to increase the efficiency of the alloys as thermocouples in thermal-to-electrical energy conversion,” Heremans said. 

Thermoeletric (TE) materials convert heat to electricity directly. When a temperature gradient is applied to a piece of TE material, voltage can be measured across the two ends of the sample. The term "thermopower" refers to the ratio of the voltage to the temperature difference.

Metals are generally not considered to be good TE materials since they have too many charge carriers compared with semiconductors, which limits their thermopower and energy conversion efficiency. The advantages of metallic alloys over inorganic semiconductors are that they are strong, easy to produce and form into net shapes, and can be welded.  “We are interested in Fe-Co alloys because they are ferromagnets,” said Zheng.

The spin procession of the 3d electrons of the ferromagnets are in wave forms and can be described by the quasiparticle magnons. These magnons are involved in the transport of electrons and increases the thermopower by drag effects.  “If we can improve the thermopower of Fe-Co alloys by magnon drag effect, they can be very useful,” Zheng said.

About the Materials Research Society

Founded in 1973 and headquartered in Warrendale, Pennsylvania, the Materials Research Society is a growing, vibrant member-driven organization of almost 16,000 men and women from over 90 countries around the world—from the richest of nations to developing countries.  Membership comes from industry, academia and national labs encompassing many fields, including chemistry, biology, physics and engineering.  The Society’s mission is to advance materials and improve the quality of life.