A5080300367- Thermal properties of materials
- Carbon Nanotubes in Composites
- Thermal Radiation and Cooling Technologies
- Advanced Thermoelectric Materials and Devices
- Graphene research and applications
- Heat Transfer and Optimization
- Diamond and Carbon-based Materials Research
- Adhesion, Friction, and Surface Interactions
- Optical properties and cooling technologies in crystalline materials
- Advanced battery technologies research
- Transition Metal Oxide Nanomaterials
- Force Microscopy Techniques and Applications
- Photonic and Optical Devices
- Conducting polymers and applications
- Tribology and Wear Analysis
- Nanowire Synthesis and Applications
- Thermography and Photoacoustic Techniques
- Supercapacitor Materials and Fabrication
- Gas Sensing Nanomaterials and Sensors
- Energy Harvesting in Wireless Networks
- Microfluidic and Capillary Electrophoresis Applications
- Plasmonic and Surface Plasmon Research
- Nanopore and Nanochannel Transport Studies
- Ionic liquids properties and applications
- Mechanical and Optical Resonators
Georgia Institute of Technology
2011-2020
AID Atlanta
2014-2018
University of Georgia
2016
Purdue University West Lafayette
2006-2010
State Street (United States)
2009-2010
Vanderbilt University
2005-2006
Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs SWCNTs highlight key ongoing research areas challenges. A few applications that capitalize on properties are also reviewed with respect ways which science can enable advances these While primary focus this is framework SWCNT growth, draw connections mechanisms underlying other 1D 2D materials...
Low efficiencies and costly electrode materials have limited harvesting of thermal energy as electrical using thermo-electrochemical cells (or "thermocells"). We demonstrate thermocells, in practical configurations (from coin to that can be wrapped around exhaust pipes), harvest low-grade relatively inexpensive carbon multiwalled nanotube (MWNT) electrodes. These electrodes provide high electrochemically accessible surface areas fast redox-mediated electron transfer, which significantly...
Continuously operating thermo-electrochemical cells (thermocells) are of interest for harvesting low-grade waste thermal energy because their potentially low cost compared with conventional thermoelectrics. Pt-free thermocells devised here provide an output power 12 W m-2 interelectrode temperature difference (ΔT) 81 °C, which is sixfold higher than previously reported planar at ambient pressure.
This work describes an experimental study of thermal conductance across multiwalled carbon nanotube (CNT) array interfaces, one sided (Si-CNT-Ag) and two (Si-CNT-CNT-Cu), using a photoacoustic technique (PA). Well-anchored, dense, vertically oriented CNT arrays have been directly synthesized on Si wafers pure Cu sheets plasma-enhanced chemical vapor deposition. With the PA technique, small interface resistances highly conductive interfaces can be measured with accuracy precision. In...
The thermal performance of an interface material comprised a metal foil with dense, vertically oriented carbon nanotube (CNT) arrays synthesized on both its surfaces is characterized for rough and smooth interfaces. CNT/foil deforms in the interfaces by two mechanisms, CNT deformation deformation, that may significantly increase number contact spots sides foil. As result, resistances less than 10mm2K∕W are achieved at moderate pressures compare very favorably to alternative materials structures.
A method has been developed to create vertically aligned carbon nanotube (VACNT) thermal interface materials that can be attached a variety of metallized surfaces. VACNT films were grown on Si substrates using standard CVD processing followed by metallization Ti/Au. The coated CNTs then bonded at 220 °C. By reducing the adhesion VACNTs growth substrate during synthesis, completely transferred from and used as die attachment material for electronic components. Thermal resistance measurements...
We report mechanical behavior and strain rate dependence of recoverability energy dissipation in vertically aligned carbon nanotube (VACNT) bundles subjected to quasi-static uniaxial compression. observe three distinct regimes their stress–strain curves for all explored rates from 4 × 10–2 down 10–4 /sec: (1) a short initial elastic section followed by (2) sloped plateau with characteristic wavy features corresponding buckle formation (3) densification characterized rapid stress increase....
Abstract Current understanding of phonons treats them as plane waves/quasi-particles atomic vibration that propagate and scatter. The problem is conceptually, when any level disorder introduced, whether compositional or structural, the character vibrational modes in solids changes, yet nearly all theoretical treatments continue to assume are still waves. For example, phonon contributions alloy thermal conductivity (TC) rely on this assumption most often computed from virtual crystal...
In this work, we investigate the thermal boundary resistance and conductivity of GaN layers grown on Si with 100 nm AlN transition using time domain thermoreflectance (TDTR). The ranged from 0.31 to 1.27 μm. Due challenges in determining buried interfaces found architecture, a new data reduction scheme for TDTR that utilizes Monte Carlo fitting method is introduced dramatically reduce uncertainty certain model parameters. results show does not change significantly layer thickness, whereas...
The development of electronic devices, especially those that involve heterogeneous integration materials, has led to increased challenges in addressing their thermal operational temperature demands. heat flow these systems is significantly influenced or even dominated by boundary resistance at the interface between dissimilar materials. However, controlling and tuning transport across an adjacent materials so far drawn limited attention. In this work, we grow chemical vapor-deposited diamond...
Waste heat recovery with thermo-electrochemical cells is limited by their low power and conversion efficiencies.
We explore the prospects of using doped carbon nanotube (CNT) electrodes to increase output power thermo-electrochemical cells (TECs). CNT buckypaper with nitrogen and boron were characterized cyclic voltammetry, impedance spectroscopy, TEC test potassium ferri/ferrocyanide electrolyte. Both doping states increased electrochemically active surface area electrodes. Electrostatic interactions ions altered charge transfer kinetics for electrodes; yet, symmetry remained approximately equal that...
The maximum output power of GaN-based high-electron mobility transistors is limited by high channel temperature induced localized self-heating, which degrades device performance and reliability. Chemical vapor deposition (CVD) diamond an attractive candidate to aid in the extraction this heat minimizing peak operating temperatures high-power electronics. Owing its inhomogeneous structure, thermal conductivity CVD varies along growth direction can differ between in-plane out-of-plane...
The spectral characteristics of near-field thermal emission from nanoparticle arrays are explained by comparison to the dispersions for propagating modes. Using coupled dipole model, we analytically calculate single particles, chains, planes, and three-dimensional $\mathrm{Si}{\mathrm{O}}_{2}$ SiC. We show that differences in their spectra due existence or absence surface phonon polariton modes is dominated these when they present. This work paves way understanding control radiation...
Systems of many nanoparticles or volume-discretized bodies exhibit collective radiative properties that could be used for enhanced, guided, tunable thermal radiation. These are commonly treated as assemblies point dipoles with interactions described by Maxwell's equations and fluctuations correlated the fluctuation-dissipation theorem. Here, we demonstrate equivalence different theories these systems provide a complete derivation many-dipole radiation, showing correct use theorem depends on...
Reduction of contact resistance is demonstrated at Cu–Cu interfaces using a multiwalled carbon nanotube (MWCNT) layer as an electrically conductive interfacial material. The MWCNTs are grown on copper substrate plasma enhanced chemical vapour deposition (PECVD) with nickel the catalyst material, and methane hydrogen feed gases. showed random growth directions had bamboo-like structure. Contact reaction force were measured for bare interface Cu–MWCNT–Cu function probe position. For apparent...
Multi-walled carbon nanotubes (MWCNTs) with systematically varied diameter distributions and defect densities were reproducibly grown from a modified catalyst structure templated in an amine-terminated fourth-generation poly(amidoamine) (PAMAM) dendrimer by microwave plasma-enhanced chemical vapor deposition. Thermal interface resistances of the vertically oriented MWCNT arrays as determined photoacoustic technique reveal strong correlation quality assessed Raman spectroscopy. This study...
Electrodeposition of nanowire array in porous anodic alumina (PAA) templates combine the performance benefits offered by crystallographic texture control, lattice thermal conductivity suppression through boundary scattering phonons, elastic relaxation misfit strain, and scalablity essential for high efficiency thermoelectric devices. The template material, however, can serve as a shunt thereby reducing effective performance. Here, we demonstrate process minimizing parasitic conduction...
The next generation of thermal interface materials (TIMs) are currently being developed to meet the increasing demands high-powered semiconductor devices. In particular, a variety nanostructured materials, such as carbon nanotubes (CNTs), interesting due their ability provide low resistance heat transport from device-to-spreader and compliance between with dissimilar coefficients expansion (CTEs), but few application-ready configurations have been produced tested. Recently, we undertaken...
Efforts to utilize the high intrinsic thermal conductivity of carbon nanotubes (CNTs) for transport applications, namely interface materials (TIMs), have been encumbered by presence contact resistances between CNTs and connecting materials. Here, a pyrenylpropyl‐phosphonic acid surface modifier is synthesized applied in straight forward repeatable approach reduce resistance metal oxide surfaces. When used bond nominally vertically aligned multi‐walled CNT forests Cu surfaces, facilitates...