Positions open: We may
have positions for postdoc
fellows, graduate students, and undergraduate students. Please check here.
10/2017: Invited Seminar.
Dr. Ruan gave an invited seminar at
the University of California at Santa Barbara.
08/2017: Student award.
Joseph Peoples joined our
group as a Ph.D. student and receives the Winkelman Fellowship
from the School of Mechanical Engineering.
08/2017: Welcome New
Students. Joseph Peoples and Zhixuan (Victoria) Zhao have joined our group. Welcome!
07/2017: PhD dissertation
defense. Tianli successfully defended his PhD
dissertation and will join Vanderbilt University/Oak Ridge
National Laboratory as a postdoc fellow. Congratulations,
07/2017: Invited Talk.
give an invited talk at the 9th US-Japan Joint Seminar on
Nanoscale Transport Phenomena held in Tokyo, Japan.
Sustainable energy and energy
efficiency are among the greatest challenges facing the society, and heat
transfer scientists and engineers can contribute. Solutions to these
challenges rely on extraordinarily fundamental and
innovative approaches. In our lab, we are developing
efficient energy and renewable energy technologies using the emerging nanotechnology.
The behavior of all energy systems
related to atomic-scale description. With an atomic-level
knowledge of the thermal energy carriers (photon, electron, phonon,
and fluid particle), one is
able to design nano- and micro-structures with
the desired size effects, or to synthesize new materials
with the desired functionalities. Our lab is building and expanding
the understanding of the fundamentals of atomic-level
carrier transport and interactions, and is applying this
knowledge to important applications for energy efficiency and electronics thermal
Current projects fall in two
nanoscale heat conduction, and nano-photonics (including nanoscale thermal radiation).
Projects in the nanoscale heat conduction (or
nano-phononics) category include: (1) high-performance nanostructured
thermoelectric materials for power generation and
thermoelectric refrigeration; (2) thermal transport and thermal
rectification in carbon nanotube and graphene for electronic
thermal management applications; (3) thermal
interface resistance across CNT (or graphene)-metal
interfaces for electronic thermal management applications. Projects in the nano-photonics category include: (4)
Suppression of electron-phonon
coupling in quantum dot solar cell materials for enhanced
efficiency; (5) Enhanced
optical absorption in silicon nanowire arrays for
potentially enhanced solar cell efficiency; (6) Multiscale control of
thermal radiation in ordered array of carbon nanotubes; (7)
enhanced laser cooling of semiconductors and ion-doped
projects involve theoretical, computational, and experimental
components. Currently our lab devotes 2/3 efforts to
theoretical and simulation studies, and 1/3 effort to
experimental work. Theoretical tools include heat transfer,
materials science, quantum mechanics,
solid state physics, optics, and electromagnetic theory. Computational
tools involve multiscale
simulation techniques of nanoscale energy transport,
including molecular dynamics simulations, first principles
simulations, and Boltzmann transport theory. Experiments
include fabrication of nanomaterials and devices, and
characterizations of these materials and devices using
advanced imaging and spectroscopy
techniques. Detailed information of our research can be
We have labs in both the
ME building and the
Birck Nanotechnology Center. We are also associated with
Energy Center at Purdue.
Most Recent Publications:
J. Walter, T.L. Feng, J. Zhu, H. Zheng, J.F.
Mitchell, N. Biškup, M. Varela, X.L. Ruan, C. Leighton, and
X.J. Wang, “Glass-like Through-Plane Thermal
Conductivity Induced by Oxygen Vacancies in Nanoscale
Advanced Functional Materials
Feng, L. Lindsay, and X.L. Ruan, “Four phonon scattering
significantly reduces thermal conductivity is solids,”
Phys. Rev. B Rapid Communications,
161201(R) (2017). [PDF]
Li, W. Park, Y.P. Chen, and X.L. Ruan, “Absence of coupled
thermal interfaces in Al2O3/Ni/Al2O3
sandwich structure,” Appl. Phys. Lett. 111,
143102 (2017). [PDF]
 H. Bao, C. Yan, B.X. Wang, X.
Fang, C.Y. Zhao, and X.L. Ruan, "Double-layer nanoparticle-based
coatings for efficient terrestrial radiative
cooling", Solar Energy Materials and Solar Cells 168, 78–84
 T.L. Feng, W.J. Yao, Z.Y. Wang,
J.J. Shi, C. Li, B.Y. Cao, and X.L. Ruan, "Spectral analysis
of nonequilibrium molecular dynamics: Spectral phonon
temperature and local nonequilibrium in thin films and
across interfaces", Phys. Rev. B 95, 195202 (2017). [PDF]
X.Y. Li, N. Mandal, X.L. Ruan, and Y.P. Chen, "Compressive
mechanical response of graphene foams and their thermal
resistance with copper interfaces", APL Materials 5, 036102
list of publications]