Solid-State Thermal Switching by Controlling Soft Phonons and Crystal Symmetry
Abstract
Approved for Public Release)Solid-state thermal switches, whose thermal conductivity can be significantly changed with high speeds,,would enable transformative capabilities aligned with the DoD s mission. These include flexible thermal management of fast-charging,batteries, electronics on spacecrafts, biomedical devices, and potential realization of thermal logic devices, computers and neural,networks. Existing thermal switches, however, do not meet the requirements for these applications. The main difficulty is the lack o,f control due to the weak response of the heat-carrying lattice vibrations (phonons) to external stimuli.To address this challenge,,we propose to develop the fundamental understanding of a novel approach to realize solid-state thermal switches by tuning soft phono,ns and controlling crystal symmetry breaking. We aim to identify promising thermal-switching materials combining state-of-the-art fi,rst-principles modeling and phonon/thermal characterization techniques. Based on the fundamental understandings, we will collaborate, with material scientists to develop fabrication techniques and devices that allow for thermal switches that can be integrated into,a wide range of existing electronic and energy systems. We organize our efforts in three main Tasks:Task 1 will focus on controlling, the ultrasoft optical phonons in topological semimetals due to strong electron-phonon coupling caused by Kohn anomalies associated,with the Dirac nodes. External electric field can sensitively tune the size of the Fermi surface, leading to significant change of p,honon scattering and the lattice thermal conductivity. We will also explore using topological phase transitions induced by pressure,or strain.Task 2 will focus on the soft ferroelectric phonon modes in tunable dielectric oxides near their ferroelectric transitions,. The frequency of the ferroelectric phonon modes can be significantly influenced by an external electric field, enabling large chan,ge of the phonon scattering phase space and thus the lattice thermal conductivity.Task 3 will combine group theory with first-princi,ples simulations to elucidate the impact of crystal symmetry breaking on the phonon scattering selection rules in high-symmetry mate,rials. We will experimentally verity the theoretical predictions by examining electric field and strain gradient induced symmetry br,eaking.Furthermore, novel application concepts enabled by effective solid-state thermal switches will be explored, including neuromo,rphic computing with thermal neural networks and simultaneous switching of conduction and radiation for spacecrafts. If successful,,this program will not only enable the development of high-performance thermal switches, but also establish new materials, theory and, characterization techniques for the thermal transport research.As an educational institution, UCSB performs fundamental and unclass,ified research. Any data or information developed or provided by UCSB, including but not limited to publications and reports, shall,be unclassified fundamental research exempt from dissemination controls or review requirements.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 08, 2022
- Source ID
- N000142212262
Entities
People
- Bolin Liao
Organizations
- Office of Naval Research
- United States Navy
- University of California, Santa Barbara