At the invitation of the School of Physics of Lanzhou University, the Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education, and the Cuiying College, researcher Li Ming from the Shenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, visited and gave an academic report. Teachers and students are welcome to participate!

Report title: Thermal Functional Materials Research

Time:2020-11-23, 14:30

Location: Room 1318 in Ligong Building

Abstract:

More than 90% of energy use today involves the generation, control and transportation of heat energy, and the refrigeration process is a typical example. Refrigeration technology has played a vital role in social industrial and agricultural production, daily life and other fields. At present, refrigeration mainly relies on traditional gas compression refrigeration technology, and refrigerants with a strong greenhouse effect are widely used, which directly contributes 7.8% of the total social carbon emissions. The phase change process of solid materials is accompanied by huge heat absorption or exothermic effects, so external forces such as gas pressure, hydrostatic pressure, magnetic field, electric field and other external forces are often used to control the phase change of the material to achieve refrigeration. This is solid phase change refrigeration, which is considered to be the most promising One of the alternative gas compression technology solutions. However, for a long time, the performance of solid phase change refrigeration materials is far from reaching the application requirements. Here, we will report the newly discovered plastic crystal pressure card effect. The isothermal entropy change of these materials is an order of magnitude higher than that of traditional solid phase change refrigeration materials, and these materials are extremely cheap, with extremely low driving pressure, and have very attractive application prospects. Using high-pressure neutron scattering and synchrotron radiation X-ray scattering, it is revealed that this unique effect comes from a new physical mechanism, that is, the suppression of molecular orientation disorder by pressure. The discovery of the Ponzika effect provides a brand new idea for the basic research and application development of solid phase change refrigeration materials. In addition, the recently discovered dimer rattling mode and the peculiar heat conduction properties caused by it will also be reported.

(Translated by Heyipeng, proofread by Bian Yujing and Li Shuowen)