A5043172999- Advanced Thermoelectric Materials and Devices
- Thermal properties of materials
- Heusler alloys: electronic and magnetic properties
- Thermal Radiation and Cooling Technologies
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and interfaces
- Advanced Thermodynamics and Statistical Mechanics
- Thermodynamic and Structural Properties of Metals and Alloys
- Intermetallics and Advanced Alloy Properties
- Thermal Expansion and Ionic Conductivity
- Semiconductor Quantum Structures and Devices
- Magnetic and transport properties of perovskites and related materials
- Silicon and Solar Cell Technologies
- Silicon Nanostructures and Photoluminescence
- Surface and Thin Film Phenomena
- MXene and MAX Phase Materials
- nanoparticles nucleation surface interactions
- Topological Materials and Phenomena
- Gas Sensing Nanomaterials and Sensors
- Graphene research and applications
- Nuclear Materials and Properties
- Metallurgical and Alloy Processes
- Machine Learning in Materials Science
- Transition Metal Oxide Nanomaterials
- Chemical and Physical Properties of Materials
Nanohmics (United States)
2018-2023
Boston College
2007-2013
Massachusetts Institute of Technology
2008
A dimensionless thermoelectric figure-of-merit (ZT) of 0.95 in p-type nanostructured bulk silicon germanium (SiGe) alloys is achieved, which about 90% higher than what currently used space flight missions, and 50% the reported record SiGe alloys. These materials were made by using a direct current-induced hot press mechanically alloyed nanopowders that initially synthesized ball milling commercial grade Si Ge chunks with boron powder. The enhancement ZT due to large reduction thermal...
The dimensionless thermoelectric figure of merit (ZT) the n-type silicon germanium (SiGe) bulk alloy at high temperature has remained about one for a few decades. Here we report that by using nanostructure approach, peak ZT 1.3 900 °C in an nanostructured SiGe been achieved. enhancement comes mainly from significant reduction thermal conductivity caused enhanced phonon scattering off increased density nanograin boundaries. will make such materials attractive many applications as solar,...
The peak dimensionless thermoelectric figure-of-merit (ZT) of Bi(2)Te(3)-based n-type single crystals is about 0.85 in the ab plane at room temperature, which has not been improved over last 50 years due to high thermal conductivity 1.65 W m(-1) K(-1) even though power factor 47 x 10(-4) K(-2). In samples with random grain orientations, we found that can be decreased by making size smaller through ball milling and hot pressing, but a similar percentage, resulting no gain ZT. Reorienting...
We introduce the concept of modulation doping in three-dimensional nanostructured bulk materials to increase thermoelectric figure merit. Modulation-doped samples are made two types nanograins (a two-phase composite), where dopants incorporated only into one type. By band engineering, charge carriers could be separated from their parent grains and moved undoped grains, which would result enhanced mobility comparison uniform due a reduction ionized impurity scattering. The electrical...
Half-Heuslers would be important thermoelectric materials due to their high temperature stability and abundance if dimensionless figure of merit (ZT) could made enough. The highest peak ZT a p-type half-Heusler has been so far reported about 0.5 the thermal conductivity. Through nanocomposite approach using ball milling hot pressing, we have achieved 0.8 at 700 °C, which is 60% higher than best might good enough for consideration waste heat recovery in car exhaust systems. improvement comes...
Abstract An enhancement in the dimensionless thermoelectric figure‐of‐merit ( ZT ) of an n‐type half‐Heusler material is reported using a nanocomposite approach. A peak value 1.0 was achieved at 600 °C–700 °C, which about 25% higher than previously highest value. The samples were made by ball‐milling ingots composition Hf 0.75 Zr 0.25 NiSn 0.99 Sb 0.01 into nanopowders and hot‐pressing powders dense bulk samples. formed arc‐melting elements. mainly comes from reduction thermal conductivity...
The mechanism for phonon scattering by nanostructures and point defects in nanostructured silicon (Si) the germanium (Ge) alloy their thermoelectric properties are investigated. We found that thermal conductivity is reduced a factor of 10 Si comparison with bulk crystalline Si. However, nanosize interfaces not as effective phonons wavelengths shorter than 1 nm. further 5 at. % Ge replacing very efficient nm, resulting reduction 2, thereby leading to figure merit 0.95 Si95Ge5, similar large...
We report a peak dimensionless figure-of-merit (ZT) of ∼1 at 700 °C in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05 composition. Even though the power factor composition is improved by 25%, comparison to previously reported Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, ZT value not increased due higher thermal conductivity. However, led 15% increase output thermoelectric device made from previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type used make unicouple Hf0.25Zr0.75NiSn0.99Sb0.01 with...
Nanocomposite thermoelectric materials have attracted much attention recently due to experimental demonstrations of improved properties over those the corresponding bulk material. In order better understand reported data and gain insight into transport in nanocomposites, we use Boltzmann equation under relaxation-time approximation calculate $n$-type $p$-type SiGe nanocomposites. We account for strong grain-boundary scattering mechanism nanocomposites using phonon electron models. The...
Traditional processes of making contacts (metallization layer) onto bulk crystalline Bi2Te3-based materials do not work for nanostructured thermoelectric either because weak bonding strength or an unstable contact interface at temperatures higher than 200 °C. Hot pressing nickel legs in a one-step process leads to strong bonding. However, such results large resistance n-type Ni/Bi2Te2.7Se0.3/Ni legs, although p-type Ni/Bi0.4Sb1.6Te3/Ni legs. A systematic study was carried out investigate the...
Thermoelectric properties of dense bulk polycrystalline ${\mathrm{In}}_{4}{\mathrm{Se}}_{3\ensuremath{-}x}$ ($x$ $=$ 0, 0.25, 0.5, 0.65, and 0.8) compounds are investigated. A peak dimensionless thermoelectric figure merit ($\mathit{ZT}$) about 1 is achieved for $x$ 0.65 0.8. The $\mathit{ZT}$ 50% higher than the previously reported highest value compounds. Our samples were prepared by ball milling hot pressing. We show that it possible to effectively control electrical conductivity thermal...
In this paper, we investigate the phonon transport in silicon nanocomposites using Monte Carlo simulations considering frequency-dependent mean free paths, and combine modeling with electron to predict thermoelectric figure of merit (ZT) nanocomposites. The model shows that while grain interface scattering phonons is negligible for large sizes around 200 nm, ZT can reach 1.0 at 1173 K if size be reduced 10 nm. Our results show potential obtaining a high bulk by nanocomposite approach.
Nanostructuring has been shown to be an effective approach reduce the lattice thermal conductivity and improve thermoelectric figure of merit. Because experimentally measured includes contributions from both carriers phonons, separating out phonon contribution difficult is mostly based on estimating electronic using Wiedemann-Franz law. In this paper, experimental method directly measure presented applied Cu${}_{0.01}$Bi${}_{2}$Te${}_{2.7}$Se${}_{0.3}$,...
The demand for high‐performance materials in thermoelectric (TE) technology has driven continuous efforts to enhance the performance of commercialized Bi 2 Te 3 ‐based materials. Here, we report success achieving significant improvements n‐type 2.8 Se 0.2 S 0.01 through implementation a hot extrusion manufacturing process. This tailored process yielded desired microstructure characterized by grain growth and preferred orientations. resulting enlarged grain‐based exhibits reduced dislocations...
The pulsed light annealing process improves the efficiency of bismuth telluride based thermoelectric devices by reducing contact resistance significantly.
Nanostructured Ni-doped skutterudites Co(1-x)Ni(x)Sb3 (with x ranging from 0.01 to 0.09) were prepared by ball milling and direct-current induced hot press. It was found that the thermal conductivity reduced due strong electron-phonon scattering Ni-doping as well phonon increased grain boundary of nanostructures. A maximum dimensionless figure-of-merit 0.7 obtained in Co0.91Ni0.09Sb3 at 525 degrees C.
Evaluating the performance of thermoelectric (TE) materials is critical for developing an efficient long lasting generator. Various parameters like resistance, TE power, efficiency as a function temperature and time play important role in optimizing legs. If one needs to evaluate legs or contact metallization optimization, study brazed packaged device everytime could prove be expensive, consuming process especially quick intermediate qualification. In this work, simple approach that uses...