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Colloquium: Colossal barocaloric effects in plastic crystals

ABSTRACT

Caloric materials are systems that exhibit significant thermal effects at phase transitions induced by external fields like temperature, pressure, stress, magnetic fields and so forth. They can be used for the solid-state refrigeration through a designated cooling cycle. The core physical issue of caloric materials is the evolutions of atomic structures and interactions as a function of these driving forces in multiple spatial and temporal scales. State-of-the-art characterization techniques based on large-scale facilities such as the neutron scattering are highly desirable in this case due to the powerful experimental abilities and versatile sample environments. Very recently, we have reported colossal barocaloric effects (CBCEs) (barocaloric effects are the cooling effects of pressure-induced phase transitions) in a class of disordered solids called plastic crystals. The obtained entropy changes in a representative plastic crystal, neopentylglycol, are about 389 joules per kilogram per kelvin near room temperature. Pressure-dependent neutron scattering measurements reveal that CBCEs in plastic crystals can be attributed to the combination of extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of these materials. Our study establishes the microscopic mechanism of CBCEs in plastic crystals and paves the way to next-generation solid-state refrigeration technologies.
 

BIOGRAPHY

Prof Bing Li is currently a full professor in the Institute of Metal Research Chinese Academy of Sciences. He is the Deputy Division Head of the Functional Materials and Devices Division and the principle investigator of the neutron scattering group in Shenyang National Laboratory for Materials Science. His major research involves the preparations and characterizations of novel caloric materials and other emergent energy materials. He emphasizes to utilize neutron scattering and X-ray scattering methods. He has published more than 40 papers on leading academic journals, such as on Nature, Nature Materials, and Nature Communications. He has been recruited into the National Oversea Young Talents Project since 2019. He is now the Chief Scientist of the Major Program for the Fundamental Research of the Chinese Academy of Sciences.

Event Details
Speaker
Prof Bing Li
Full professor, Institute of Metal Research Chinese Academy of Sciences

Date & Time
1 November 2019 3:00 pm

Venue
G4302 Yeung Kin Man Academic Building, City University of Hong Kong

Chair
Prof Xun-Li Wang (3442 9140 phy.head@cityu.edu.hk)