BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:Extraordinary heat transport at the nanoscale DTSTART:20180216T131500 DTEND:20180216T141500 DTSTAMP:20260506T020318Z UID:f9eeca233152fe6450393b9ddc97d4926e3604b1f503eae07971c1db CATEGORIES:Conferences - Seminars DESCRIPTION:Dr. BAI SONG\, NanoEngineering Group\, MIT\nAbstract:\nHeat c arriers such as photons and phonons are ultimately waves\, however\, the w ave nature of heat has remained rather elusive in thermal transport. As so me examples\, nanoscale thermal radiation and phonon localization will be discussed in this talk. Radiative heat transfer between objects separated by  nanometer-sized gaps is of considerable interest for a variety of nov el applications\, including energy conversion\, thermal logic\, lithograph y\, data storage\, and scanning thermal microscopy. Although thermal radia tion over macroscopic distances is well understood in terms of Planck’s law and the Stefan-Boltzmann law\, radiative heat transfer at the nanoscal e remains largely unexplored. Here I will address two foundational questio ns in the field:\n1) Can existing  theories accurately describe radiative heat transfer across few-nanometer gaps?\n2) Can radiative heat flow exce ed the blackbody limit by a few orders of magnitude? To answer these chall enging questions\, I built novel experimental platforms featuring nanomete rprecise positioning mechanisms in conjunction with novel heater/calorimet er microdevices and scanning probes. Further\, I performed state-of-the-ar t calculations and analysis to compare theoretical predictions with experi mental observations\nI will demonstrate that:\n1) Current nanoscale radiat ion theories can adequately describe radiative heat transfer down to about 1 nm gaps.\n2) Radiative heat flow between two parallel planes can exceed the blackbody limit by over 1000 times.\nThese advances open up many new opportunities in the emerging field of nanoscale thermal radiation. To wra p up\, I will briefly discuss whether localization of thermal phonons can take place in 3D materials and be experimentally demonstrated. The departu re from diffusive Fourier transport has been widely observed in nanostruct ures and largely explained with classical size effects on phonon gas\, ign oring the wave nature of phonons. I will discuss our recent\nwork on phono n localization in heat conduction through quantum-dot superlattices\, due to multiple scattering and interference of coherent phonon waves. This dis covery is surprising given the broadband nature of thermal transport\, and suggests a new path for engineering phonon transport. Altogether\, I hope to show a glimpse of the beauty and potential of heat transport at the na noscale.\n\nBio:\nDr. Bai Song is a postdoctoral associate at MIT\, mentor ed by Prof. Gang Chen in the Mechanical Engineering Department. He earned his PhD in 2015 at the University of Michigan\, Ann Arbor\, where he was h onored with the Distinguished Dissertation Award.\nHe obtained his MS and BE at Tsinghua University\, Beijing\, and was a recipient of the Distingui shed Master Thesis Award. His primary research interest is to understand h eat transport\, conversion\, storage and dissipation\, in diverse material s\, devices and systems\, and especially at small spatial and temporal sca les. He further aims to leverage such knowledge to develop engineering sol utions to real-world challenges such as the global energy and environmenta l problems\, and thermal management of buildings\, spacecrafts and microel ectronics. LOCATION:MED 0 1418 https://plan.epfl.ch/?room==MED%200%201418 STATUS:CONFIRMED END:VEVENT END:VCALENDAR