Critical role of nanoinclusions in silver selenide nanocomposites as a promising room temperature thermoelectric material

The introduction of nonmetal nanoinclusions within Ag2Se results in an interphase band bending that promotes electron filtering and increase Seebeck coefficient. Similar loading of metal nanoinclusions provided an opposite effect-modulating free carrier concentration, as characterized by superior electrical conductivities and lower Seebeck coefficients.

Download Full-text

Annealing Effect on the Thermoelectric Properties of Bi2Te3Thin Films Prepared by Thermal Evaporation Method

Journal of Nanomaterials ◽

10.1155/2013/201017 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 8

Author(s):

Jyun-Min Lin ◽

Ying-Chung Chen ◽

Chi-Pi Lin

Keyword(s):

Thin Films ◽

Seebeck Coefficient ◽

Thermoelectric Properties ◽

Power Factor ◽

Room Temperature ◽

Annealing Temperature ◽

Thermal Evaporation ◽

Thermal Evaporation Method ◽

Si Substrates ◽

Seebeck Coefficients

Bismuth telluride-based compounds are known to be the best thermoelectric materials within room temperature region, which exhibit potential applications in cooler or power generation. In this paper, thermal evaporation processes were adopted to fabricate the n-type Bi2Te3thin films on SiO2/Si substrates. The influence of thermal annealing on the microstructures and thermoelectric properties of Bi2Te3thin films was investigated in temperature range 100–250°C. The crystalline structures and morphologies were characterized by X-ray diffraction and field emission scanning electron microscope analyses. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature. The experimental results showed that both the Seebeck coefficient and power factor were enhanced as the annealing temperature increased. When the annealing temperature increased to 250°C for 30 min, the Seebeck coefficient and power factor of n-type Bi2Te3-based thin films were found to be about −132.02 μV/K and 6.05 μW/cm·K2, respectively.

Download Full-text

Silicide/Silicon Hetero-Junction Structure for Thermoelectric Applications

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11148 ◽

2015 ◽

Vol 15 (10) ◽

pp. 7472-7475 ◽

Cited By ~ 1

Author(s):

Dongsuk Jun ◽

Soojung Kim ◽

Wonchul Choi ◽

Junsoo Kim ◽

Taehyoung Zyung ◽

...

Keyword(s):

Thermal Conductivity ◽

Seebeck Coefficient ◽

Electrical Energy ◽

Multilayered Structure ◽

Thermoelectric Device ◽

Cmos Process ◽

Platinum Silicide ◽

Seebeck Coefficients ◽

Heating And Cooling ◽

Electrical Conductivities

We fabricated silicide/silicon hetero-junction structured thermoelectric device by CMOS process for the reduction of thermal conductivity with the scatterings of phonons at silicide/silicon interfaces. Electrical conductivities, Seebeck coefficients, power factors, and temperature differences are evaluated using the steady state analysis method. Platinum silicide/silicon multilayered structure showed an enhanced Seebeck coefficient and power factor characteristics, which was considered for p-leg element. Also, erbium silicide/silicon structure showed an enhanced Seebeck coefficient, which was considered for an n-leg element. Silicide/silicon multilayered structure is promising for thermoelectric applications by reducing thermal conductivity with an enhanced Seebeck coefficient. However, because of the high thermal conductivity of the silicon packing during thermal gradient is not a problem any temperature difference. Therefore, requires more testing and analysis in order to overcome this problem. Thermoelectric generators are devices that based on the Seebeck effect, convert temperature differences into electrical energy. Although thermoelectric phenomena have been used for heating and cooling applications quite extensively, it is only in recent years that interest has increased in energy generation.

Download Full-text

Role of Heat Expansion with a Series of Ionic Liquids: The Case for Isochoric Thermoelectric Generators and Minimal Steric Repulsion

Entropy ◽

10.3390/e21111086 ◽

2019 ◽

Vol 21 (11) ◽

pp. 1086

Author(s):

Marcus Jackson ◽

Robert Engel ◽

Luat Vuong

Keyword(s):

Thermal Expansion ◽

Ionic Liquids ◽

Critical Role ◽

Intramolecular Interactions ◽

Large Temperature ◽

Thermoelectric Generators ◽

Steric Repulsion ◽

Seebeck Coefficients ◽

Heat Expansion

The role of convection in liquid thermoelectric cells may be difficult to predict because the inter- and intramolecular interactions are not currently incorporated into thermodynamic models. Here, we study the thermoelectric response of a series of five anhydrous 1-methyl-3- alkylimidazolium halide ionic liquids with varied chain length and counterion in a high-aspect-ratio, horizontal-temperature-gradient geometry, where convection is minimal. While a canonical constant-volume thermodynamic model predicts that the longer aliphatic groups exhibit larger Seebeck coefficients, we instead measure the opposite: Longer aliphatic chains correlate with lower densities and greater heat expansion, stronger intermolecular associations, stronger steric repulsion, and lower Seebeck coefficients. As evidence of the critical role of thermal expansion, we measure that the Seebeck effect is nonlinear: Values of −2.8 mV/K with a 10 K temperature difference and −1.8 mV/K with a 50 K difference are measured with ether ion. Our results indicate that steric repulsion and heat expansion are important considerations in ionic liquid design; with large temperature differences, the Seebeck coefficient correlates negatively with heat expansion. Our results suggest that Seebeck values will improve if thermal expansion is limited in a pressurized, isochoric, convection-free design.

Download Full-text

Human hepatic tryptophan 2,3-dioxygenase ubiquitin-dependent protein degradation: The critical role of its exosite as the molecular lynchpin of its substrate-mediated protein stabilization

10.1101/793380 ◽

2019 ◽

Author(s):

Sung-Mi Kim ◽

Yi Liu ◽

YongQiang Wang ◽

Shay Karkashon ◽

Ariel Lewis-Ballester ◽

...

Keyword(s):

Crystal Structure ◽

Amino Acid ◽

Essential Amino Acid ◽

Opposite Effect ◽

Critical Role ◽

Protein Stabilization ◽

High Affinity ◽

Dependent Protein ◽

Rate Limiting

AbstractHepatic tryptophan 2,3-dioxygenase (TDO) is a cytoplasmic homotetrameric hemoprotein and the rate-limiting enzyme in the irreversible degradation of the essential amino acid L-tryptophan (L-Trp) to N-formylkynurenine, thus controlling the flux of L-Trp into its serotonergic and kynureninic/NAD pathways. TDO has long been recognized to be substrate-inducible via protein stabilization, but the molecular mechanism of this stabilization has remained elusive. Recent elucidation of human TDO (hTDO) crystal structure has identified a high-affinity (Kd ≈ 0.5 μM) Trp-binding exosite in each of its 4 monomeric subunits. Mutation of the Glu105, Trp208 and Arg211 comprising this exosite not only abolished the high-affinity L-Trp binding, but also accelerated the ubiquitin-dependent proteasomal degradation of hTDO. We have further characterized this hTDO degradation by documenting that its ubiquitination by gp78/AMFR and CHIP E2/E3 ligase complexes occurs on external Lys-residues within or vicinal to acidic Asp/Glu and phosphorylated pSer/pThr (DEpSpT)-clusters. Furthermore, we have identified the unstructured hTDO N- and C-termini as imparting relatively high proteolytic instability, as their deletion (ΔNC) markedly prolonged hTDO t1/2. Additionally, although previous studies reported that upon hepatic heme-depletion, the heme-free apoTDO turns over with a t1/2 ≈ 2.2 h relative to the t1/2 of 7.7 h of holoTDO, mutating the axial heme-ligating His328 to Ala has the opposite effect of prolonging hTDO t1/2. Most importantly, introducing the exosite mutation into the ΔNC-deleted or H328A-mutant completely abolished their prolonged half-lives irrespective of L-Trp presence or absence, thereby revealing that the exosite is the molecular lynchpin that defines L-Trp-mediated TDO induction via protein stabilization.

Download Full-text

Epitaxial (001) BiFeO3 thin-films with excellent ferroelectric properties by chemical solution deposition-the role of gelation

Journal of Materials Chemistry C ◽

10.1039/c4tc02371d ◽

2015 ◽

Vol 3 (3) ◽

pp. 582-595 ◽

Cited By ~ 29

Author(s):

Qi Zhang ◽

Nagarajan Valanoor ◽

Owen Standard

Keyword(s):

Thin Films ◽

Chemical Solution Deposition ◽

Room Temperature ◽

Ferroelectric Properties ◽

Critical Role ◽

Chemical Solution ◽

Solution Deposition ◽

Bifeo3 Thin Films

The critical role of gelation is demonstrated in order to achieve epitaxial (001)-BFO thin films with robust room-temperature ferroelectric properties.

Download Full-text

A Novel Thermoelectric System with Conductive Metal Rods and its Effective Seebeck Coefficients

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.459.235 ◽

2010 ◽

Vol 459 ◽

pp. 235-238

Author(s):

Tomoyuki Sasaki ◽

Yoshiomi Kondoh ◽

Osamu Hanaizumi ◽

Makoto Goto

Keyword(s):

Low Temperature ◽

Seebeck Coefficient ◽

Thermoelectric Materials ◽

External Load ◽

Room Temperature ◽

Structural Modification ◽

Seebeck Coefficients ◽

Higher Power ◽

Temperature Side

A novel linked thermoelectric system (LTES), fabricated by a simple structural modification of a conventional thermoelectric system (CTES) with the use of conductive metal rods, is characterized experimentally. The LTES generates higher power to the external load in comparison with the CTES, and the power increases with increasing length of the metal rods when the low temperature side of the system is set in the air at room temperature. In addition, measurements of Seebeck voltages of both the systems indicate that the Seebeck coefficient of thermoelectric materials in the LTES is about 1.2 times higher than that in the CTES.

Download Full-text

Selective formation of iron oxide and oxyhydroxide nanoparticles at room temperature: Critical role of concentration of ferric nitrate

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2015.01.057 ◽

2015 ◽

Vol 154 ◽

pp. 144-151 ◽

Cited By ~ 11

Author(s):

Debabrata Maiti ◽

P. Sujatha Devi

Keyword(s):

Iron Oxide ◽

Room Temperature ◽

Critical Role ◽

Ferric Nitrate ◽

Selective Formation

Download Full-text

INFLUENCE OF SILICON ADDITION ON SEEBECK COEFFICIENT OF MnSi1.7 FILMS

International Journal of Modern Physics B ◽

10.1142/s0217979211101594 ◽

2011 ◽

Vol 25 (18) ◽

pp. 2393-2402 ◽

Cited By ~ 3

Author(s):

Q. R. HOU ◽

B. F. GU ◽

Y. B. CHEN ◽

Y. J. HE

Keyword(s):

Electrical Resistivity ◽

Film Thickness ◽

Seebeck Coefficient ◽

Room Temperature ◽

Electron Beam Evaporation ◽

Aluminum Layer ◽

Seebeck Coefficients ◽

Thin Aluminum ◽

Increasing Temperature ◽

P Type

MnSi 1.7 films with different thicknesses (16–242 nm) are prepared by magnetron sputtering and electron beam evaporation. When the MnSi 1.7 film thickness is about 40 nm or above, MnSi 1.7 films are p-type in the whole temperature range (300–700 K) in agreement with reports in literature. By co-sputtering of MnSi 1.85 and silicon targets or deposition of Si / Mn multi-layers with a larger thickness ratio, silicon is added to the films and the Seebeck coefficients transform from positive to negative with increasing temperature. The Seebeck coefficients at room temperature and 633 K are +0.098 mV/K and -0.358 mV/K, respectively. By reducing the MnSi 1.7 film thickness to 27 nm, the transition of Seebeck coefficient from positive to negative is also observed although silicon is not added intentionally. When an ultra-thin aluminum layer is deposited between MnSi x(x < 1.7) and Si layers to enhance silicon diffusion, the p- to n-type transition temperature decreases about 100 K. The silicon-added MnSi 1.7 films usually have higher electrical resistivity.

Download Full-text

Boosting the Power Factor of Benzodithiophene Based Donor–Acceptor Copolymers/SWCNTs Composites through Doping

Polymers ◽

10.3390/polym12071447 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1447

Author(s):

Zhongming Chen ◽

Mengfei Lai ◽

Lirong Cai ◽

Wenqiao Zhou ◽

Dexun Xie ◽

...

Keyword(s):

Electrical Conductivity ◽

Power Factor ◽

Room Temperature ◽

Composite Films ◽

Side Chain ◽

Seebeck Coefficients ◽

Electrical Conductivities ◽

Before And After ◽

Donor Acceptor ◽

Walled Carbon Nanotubes

In this study, a benzodithiophene (BDT)-based donor (D)–acceptor (A) polymer containing carbazole segment in the side-chain was designed and synthesized and the thermoelectric composites with 50 wt % of single walled carbon nanotubes (SWCNTs) were prepared via ultrasonication method. Strong interfacial interactions existed in both of the composites before and after immersing into the 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) solution as confirmed by UV-Vis-NIR, Raman, XRD and SEM characterizations. After doping the composites by F4TCNQ, the electrical conductivity of the composites increased from 120.32 S cm−1 to 1044.92 S cm−1 in the room temperature. With increasing the temperature, the electrical conductivities and Seebeck coefficients of the undoped composites both decreased significantly for the composites; the power factor at 475 K was only 6.8 μW m−1 K−2, which was about nine times smaller than the power factor at room temperature (55.9 μW m−1 K−2). In the case of doped composites, although the electrical conductivity was deceased from 1044.9 S cm−1 to 504.17 S cm−1, the Seebeck coefficient increased from 23.76 μV K−1 to 35.69 μW m−1 K−2, therefore, the power factors of the doped composites were almost no change with heating the composite films.

Download Full-text