scholarly journals Electronic quality factor for thermoelectrics

2020 ◽  
Vol 6 (46) ◽  
pp. eabc0726 ◽  
Author(s):  
Xinyue Zhang ◽  
Zhonglin Bu ◽  
Xuemin Shi ◽  
Zhiwei Chen ◽  
Siqi Lin ◽  
...  
Keyword(s):  
Quality Factor ◽  
Room Temperature ◽  
State Of The Art ◽  
Universal Curve ◽  
Trial And Error ◽  
Single Measurement ◽  
Thermoelectric Power Factor ◽  
Commercial Applications ◽  
P Type ◽  
Single Material

Development of thermoelectrics usually involves trial-and-error investigations, including time-consuming synthesis and measurements. Here, we identify the electronic quality factor BE for determining the maximum thermoelectric power factor, which can be conveniently estimated by a single measurement of Seebeck coefficient and electrical conductivity of only one sample, not necessarily optimized, at an arbitrary temperature. We demonstrate that thousands of experimental measurements in dozens of materials can all be described by a universal curve and a single material parameter BE for each class of materials. Furthermore, any deviation in BE with temperature or doping indicated new effects such as band convergence or additional scattering. This makes BE a powerful tool for evaluating and guiding the development of thermoelectrics. We demonstrate the power of BE to show both p-type GeTe alloys and n-type Mg3SbBi alloys as highly competitive materials, at near room temperature, to state-of-the-art Bi2Te3 alloys used in nearly all commercial applications.

High thermoelectric performance of n-type Bi2Te2.7Se0.3via nanostructure engineering

2018 ◽  
Vol 6 (20) ◽  
pp. 9642-9649 ◽  
Author(s):  
D. Li ◽  
J. M. Li ◽  
J. C. Li ◽  
Y. S. Wang ◽  
J. Zhang ◽  
...  
Keyword(s):  
Thermoelectric Material ◽  
Room Temperature ◽  
Thermoelectric Performance ◽  
Commercial Applications ◽  
P Type

BiSbTe has been realized as an ideal p-type thermoelectric material near room temperature; however, its commercial applications are largely restricted by its n-type counterpart that exhibits relatively inferior thermoelectric performance.

Multiwafer Movpe of III-Nitride Films for Led and Laser Applications

1997 ◽  
Vol 482 ◽  
Author(s):  
R. Beccard ◽  
O. Schoen ◽  
B. Schineller ◽  
D. Schmitz ◽  
M. Heuken ◽  
...  
Keyword(s):  
Room Temperature ◽  
State Of The Art ◽  
Low Cost ◽  
Free Exciton ◽  
Single Layer ◽  
Laser Applications ◽  
Room Temperature Photoluminescence ◽  
Cost Of Ownership ◽  
P Type ◽  
Better Than

AbstractProcess for mass production of GaN and its related alloys, InGaN and AlGaN, have been optimized to achieve high device yield and low cost of ownership. Here we present some of the latest results obtained from AIX 2000 HT Planetary Reactor® in a configuration of 7×2” which provides unique uniformity capabilities due to the two fold rotation of the substrates. GaiN single layers with background electron concentrations below 5·1016 cm-3 and intended doping levels up to 1018 cm-3 p-type and 1020 cm-3 n-type with state of the art homogeneities have been achieved. Thickness homogeneities have been shown to be better than 1% standard deviation on full 2” wafers, while composition uniformity of ternary material is determined by room temperature photoluminescence mappings. Low temperature photoluminescence and reflectance spectra of single layer GaN revealed free exciton transitions.

Thermoelectric Properties of Ge-doped Cu3SbSe4

2011 ◽  
Vol 1314 ◽  
Author(s):  
Eric J. Skoug ◽  
Jeffrey D. Cain ◽  
Donald T. Morelli
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
State Of The Art ◽  
Unit Cell ◽  
Large Hole ◽  
Hole Effective Mass ◽  
Large Unit ◽  
Ternary Semiconductor ◽  
Large Unit Cell ◽  
P Type

ABSTRACTTernary variations of the II-VI zincblende semiconductors have received little attention for thermoelectric applications. Here we present the first systematic doping study on Cu3SbSe4, a zincblende-like ternary semiconductor with a unit cell four times larger than the parent II-VI compounds. The large unit cell of Cu3SbSe4 results in a low room temperature thermal conductivity (~3.0 W/m*K) and its large hole effective mass produces a Seebeck coefficient approaching 500 μV/K in the undoped compound. Our results show that Ge is an effective p-type dopant in Cu3SbSe4, and the power factor reaches nearly 16 μW/cm*K2 at 630K when 3% Ge is added, rivaling that of state-of-the-art thermoelectric materials at this temperature.

Thermoelectric Properties of Tl2Te-Sb2Te3 Pseudo-Binary System

2005 ◽  
Vol 886 ◽  
Author(s):  
Ken Kurisaki ◽  
Keita Goto ◽  
Atsuko Kosuga ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Binary System ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
State Of The Art ◽  
Electrical Performance ◽  
Low Thermal Conductivity ◽  
Maximum Value ◽  
P Type ◽  
Type Conduction

ABSTRACTPolycrystalline-sintered samples of thallium based substances, (Tl2Te)100−x(Sb2Te3)x (x= 0, 1, 5, 10), were prepared by melting Tl2Te and Sb2Te3 ingots followed by annealing in sealed quartz ampoules. The thermoelectric properties were measured from room temperature to around 600 K. The values of the Seebeck coefficient of all samples are positive, indicating a p-type conduction characteristic. The maximum value of the power factor is 6.53×10−4 Wm−1K−2 at 591 K obtained for x= 10 (Tl9SbTe6), which is about one order lower than those of state-of-the-art thermoelectric materials. All samples indicate an extremely low thermal conductivity, for example that of Tl2Te is approximately 0.35 Wm−1K−1 from room temperature to around 600 K. Although the electrical performance of the samples is not so good, the ZT value is relatively high due to the extremely low thermal conductivity. The maximum ZT value is 0.42 at 591 K obtained for Tl9SbTe6.

scholarly journals Demonstration of valley anisotropy utilized to enhance the thermoelectric power factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Airan Li ◽  
Chaoliang Hu ◽  
Bin He ◽  
Mengyu Yao ◽  
Chenguang Fu ◽  
...  
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Thermoelectric Power Factor ◽  
Higher Carrier Mobility ◽  
P Type

AbstractValley anisotropy is a favorable electronic structure feature that could be utilized for good thermoelectric performance. Here, taking advantage of the single anisotropic Fermi pocket in p-type Mg3Sb2, a feasible strategy utilizing the valley anisotropy to enhance the thermoelectric power factor is demonstrated by synergistic studies on both single crystals and textured polycrystalline samples. Compared to the heavy-band direction, a higher carrier mobility by a factor of 3 is observed along the light-band direction, while the Seebeck coefficient remains similar. Together with lower lattice thermal conductivity, an increased room-temperature zT by a factor of 3.6 is found. Moreover, the first-principles calculations of 66 isostructural Zintl phase compounds are conducted and 9 of them are screened out displaying a pz-orbital-dominated valence band, similar to Mg3Sb2. In this work, we experimentally demonstrate that valley anisotropy is an effective strategy for the enhancement of thermoelectric performance in materials with anisotropic Fermi pockets.

scholarly journals Global optimization of an encapsulated Si/SiO$$_2$$ L3 cavity with a 43 million quality factor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. P. Vasco ◽  
V. Savona
Keyword(s):  
Global Optimization ◽  
Photonic Crystal ◽  
Quality Factor ◽  
State Of The Art ◽  
Optimization Strategy ◽  
High Quality ◽  
Optimal Value ◽  
Out Of Plane ◽  
Fabrication Tolerances ◽  
Structural Imperfections

AbstractWe optimize a silica-encapsulated silicon L3 photonic crystal cavity for ultra-high quality factor by means of a global optimization strategy, where the closest holes surrounding the cavity are varied to minimize out-of-plane losses. We find an optimal value of $$Q_c=4.33\times 10^7$$ Q c = 4.33 × 10 7 , which is predicted to be in the 2 million regime in presence of structural imperfections compatible with state-of-the-art silicon fabrication tolerances.

scholarly journals Performance vs. hardware requirements in state-of-the-art automatic speech recognition

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Alexandru-Lucian Georgescu ◽  
Alessandro Pappalardo ◽  
Horia Cucu ◽  
Michaela Blott
Keyword(s):  
Speech Recognition ◽  
Automatic Speech Recognition ◽  
State Of The Art ◽  
Decision Makers ◽  
Computing Power ◽  
Trade Off ◽  
Speech Features ◽  
Commercial Applications ◽  
Guided Tour ◽  
Embedded Applications

AbstractThe last decade brought significant advances in automatic speech recognition (ASR) thanks to the evolution of deep learning methods. ASR systems evolved from pipeline-based systems, that modeled hand-crafted speech features with probabilistic frameworks and generated phone posteriors, to end-to-end (E2E) systems, that translate the raw waveform directly into words using one deep neural network (DNN). The transcription accuracy greatly increased, leading to ASR technology being integrated into many commercial applications. However, few of the existing ASR technologies are suitable for integration in embedded applications, due to their hard constrains related to computing power and memory usage. This overview paper serves as a guided tour through the recent literature on speech recognition and compares the most popular ASR implementations. The comparison emphasizes the trade-off between ASR performance and hardware requirements, to further serve decision makers in choosing the system which fits best their embedded application. To the best of our knowledge, this is the first study to provide this kind of trade-off analysis for state-of-the-art ASR systems.

Lead-free p-type Mn:Cs3Cu2I5 perovskite with tunable dual-color emission through room-temperature grinding method

2021 ◽  
Author(s):  
Junfeng Qu ◽  
Shuhong Xu ◽  
Fan Liu ◽  
Zhuyuan Wang ◽  
Haibao Shao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lead Free ◽  
Grinding Method ◽  
Dual Color ◽  
P Type ◽  
Color Emission

scholarly journals Review of Multi-Physics Modeling on the Active Magnetic Regenerative Refrigeration

2021 ◽  
Vol 26 (2) ◽  
pp. 47
Author(s):  
Julien Eustache ◽  
Antony Plait ◽  
Frédéric Dubas ◽  
Raynal Glises
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Room Temperature ◽  
State Of The Art ◽  
Vapor Compression ◽  
Crucial Step ◽  
Potential Alternative ◽  
Vapor Compression Refrigeration ◽  
Preliminary Study ◽  
Physics Modeling

Compared to conventional vapor-compression refrigeration systems, magnetic refrigeration is a promising and potential alternative technology. The magnetocaloric effect (MCE) is used to produce heat and cold sources through a magnetocaloric material (MCM). The material is submitted to a magnetic field with active magnetic regenerative refrigeration (AMRR) cycles. Initially, this effect was widely used for cryogenic applications to achieve very low temperatures. However, this technology must be improved to replace vapor-compression devices operating around room temperature. Therefore, over the last 30 years, a lot of studies have been done to obtain more efficient devices. Thus, the modeling is a crucial step to perform a preliminary study and optimization. In this paper, after a large introduction on MCE research, a state-of-the-art of multi-physics modeling on the AMRR cycle modeling is made. To end this paper, a suggestion of innovative and advanced modeling solutions to study magnetocaloric regenerator is described.

scholarly journals A Process for Hydrogen Production from the Catalytic Decomposition of Formic Acid over Iridium—Palladium Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3258
Author(s):  
Hamed M. Alshammari ◽  
Mohammad Hayal Alotaibi ◽  
Obaid F. Aldosari ◽  
Abdulellah S. Alsolami ◽  
Nuha A. Alotaibi ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Formic Acid ◽  
Activated Charcoal ◽  
Palladium Nanoparticles ◽  
Room Temperature ◽  
Catalytic Decomposition ◽  
Conversion Yield ◽  
Production Of Hydrogen ◽  
Commercial Applications

The present study investigates a process for the selective production of hydrogen from the catalytic decomposition of formic acid in the presence of iridium and iridium–palladium nanoparticles under various conditions. It was found that a loading of 1 wt.% of 2% palladium in the presence of 1% iridium over activated charcoal led to a 43% conversion of formic acid to hydrogen at room temperature after 4 h. Increasing the temperature to 60 °C led to further decomposition and an improvement in conversion yield to 63%. Dilution of formic acid from 0.5 to 0.2 M improved the decomposition, reaching conversion to 81%. The reported process could potentially be used in commercial applications.

Sign in / Sign up

Export Citation Format

Share Document