scholarly journals Giant enhancement of the figure-of-merit over a broad temperature range in nano-boron incorporated Cu2Se

2018 ◽  
Vol 6 (38) ◽  
pp. 18409-18416 ◽  
Author(s):  
Sheik Md. Kazi Nazrul Islam ◽  
Meng Li ◽  
Umut Aydemir ◽  
Xun Shi ◽  
Lidong Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Great Improvement ◽  
Power Factor ◽  
Figure Of Merit ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Wide Range

We demonstrate that insulating-boron nanoparticle inclusion in Cu2Se has little effect on the overall power factor, but can significantly reduce the thermal conductivity, resulting in great improvement on zT, by a factor of 1.6–2.6 compared to undoped Cu2Se over a wide range of temperatures.

FEM Analysis on Thermoelectric Properties of Metal/TiO2–x Composites with Random Distribution of Metal Powder

2013 ◽  
Vol 750 ◽  
pp. 130-133
Author(s):  
Katsuhiro Sagara ◽  
Yun Lu ◽  
Dao Cheng Luan
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Random Distribution ◽  
The Other ◽  
Dimensionless Figure Of Merit ◽  
Wide Range

Analysis model of finite element method with a random distribution for thermoelectric composites was built. Thermoelectric properties including electrical resistivity, Seebeck coefficient and thermal conductivity of M/TiO2–x (M = Cu, Ni, 304 stainless steel (304SS)) thermoelectric composites were investigated by the proposed model. Cu/TiO2–x composite showed a large decrease in electrical resistivity while 304SS/TiO2–x composite thermal conductivity was slightly increased. Calculated dimensionless figure-of-merit, ZT of Ni/TiO2–x composite was higher than those of TiO2–x and the other composites in a wide range of metal volume fractions because Ni has large absolute values of Seebeck coefficient, power factor and dimensionless figure-of-merit compared to the other two metals. It was found that power factor and dimensionless figure-of-merit of thermoelectric composites depended on the balance among electrical resistivity, thermal conductivity and Seebeck coefficient. The results revealed that it is important for M/TiO2–x composites to choose suitable addition metal with high power factor and dimensionless figure-of-merit.

Effect of High Temperature Annealing on the Thermoelectric Properties of GaP Doped SiGe

1987 ◽  
Vol 97 ◽  
Author(s):  
Jan W. Vandersande ◽  
Charles Wood ◽  
Susan Draper
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Power Factor ◽  
Silicon Germanium ◽  
Figure Of Merit ◽  
Annealing Temperature ◽  
High Temperature Annealing ◽  
Rich Phase ◽  
Temperature Range ◽  
Thermoelectric Energy

ABSTRACTSilicon-germanium alloys doped with GaP are used for thermoelectric energy conversion in the temperature range 300°C - 1000°C. The conversion efficiency depends on Z - S2/ρΛ, a material's parameter (the figure of merit), where S is the Seebeck coefficient, ρ is the electrical resistivity and Λ is the thermal conductivity. The annealing of several samples in the temperature range of 1100°C - 1300°C resulted in the power factor P (=S2/ρ) increasing with increased annealing temperature. This increase in P was due to a decrease in ρ which was not completely offset by a drop in S2 suggesting that other changes besides that in the carrier concentration took place. SEM and EDX analysis of the samples indicated the formation of a Ca- P-Ge rich phase as a result of the annealing. It is speculated that this phase is associated with the improved properties. Several reasons which could account for the improvement in the Power factor of annealed GaP doped SiGe are given.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

scholarly journals A Computational Survey of Semiconductors for Power Electronics

2019 ◽  
Author(s):  
Prashun Gorai ◽  
Robert McKinney ◽  
Nancy Haegel ◽  
Andriy Zakutayev ◽  
Vladan Stevanovic
Keyword(s):  
Thermal Conductivity ◽  
Power Electronics ◽  
Figure Of Merit ◽  
Large Scale ◽  
Lattice Thermal Conductivity ◽  
Consumer Products ◽  
Breakdown Field ◽  
Experimental Investigations ◽  
Wide Range ◽  
Screening Parameter

Power electronics (PE) are used to control and convert electrical energy in a wide range of applications from consumer products to large-scale industrial equipment. While Si-based power devices account for the vast majority of the market, wide band gap semiconductors such as SiC, GaN, and Ga2O3 are starting to gain ground. However, these emerging materials face challenges due to either non-negligible defect densities, or high synthesis and processing costs, or poor thermal properties. Here, we report on a broad computational survey aimed to identify promising materials for future power electronic devices beyond SiC, GaN, and Ga2O3. We consider 863 oxides, sulfides, nitrides, carbides, silicides, and borides that are reported in the crystallographic database and exhibit finite calculated band gaps. We utilize ab initio methods in conjunction with models for intrinsic carrier mobility, and critical breakdown field to compute the widely used Baliga figure of merit. We also compute the lattice thermal conductivity as a screening parameter. In addition to correctly identifying known PE materials, our survey has revealed a number of promising candidates exhibiting the desirable combination of high figure of merit and high lattice thermal conductivity, which we propose for further experimental investigations.

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

Thermoelectric Properties of Bi2Te3-ySey Bulk Materials Synthesized by Melting-Grinding Process

2018 ◽  
Vol 773 ◽  
pp. 145-151
Author(s):  
Min Soo Park ◽  
Gook Hyun Ha ◽  
Hye Young Koo ◽  
Yong Ho Park
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermal Characteristics ◽  
Grinding Process ◽  
Alloy Scattering ◽  
Temperature Range ◽  
P Type ◽  
Optimal Effect

The Bi–Te thermoelectric system shows an excellent figure of merit (ZT) near room temperature. Research on increasing the ZT value for n‑type Bi–Te is imperative because the thermoelectric properties of this compound are inferior to those of the p-type material. For this purpose, n-type Bi2Te3-ySey powders with various amounts of Se dopant (0.3 ≤ y ≤ 0.6) were synthesized by a vacuum melting-grinding process to improve the physical properties. The ZT value of the sintered bodies was investigated in the temperature range of 298–423 K with regard to the electrical and thermal characteristics. As the Se content increased, the electrical conductivity decreased owing to a reduction in the carrier concentration, which improved the overall value of ZT. The thermal conductivity clearly decreased as the Se content increased in the temperature range of 298–373 K due to increased alloy scattering, as well as a reduction in the lattice thermal conductivity caused by crystal grain boundary scattering. At room temperature, Bi2Te2.7Se0.3 (y = 0.3) exhibited the highest ZT of 0.85. At increased temperatures, the ZT value was highest for Bi2Te2.55Se0.45 (y = 0.45), indicating that the optimal effect of the Se dopants varies depending on the temperature range.

Effect of FAPAS Process on the Thermoelectric Properties of β-FeSi2

2010 ◽  
Vol 650 ◽  
pp. 137-141
Author(s):  
Qing Sen Meng ◽  
Wen Hao Fan ◽  
L.Q. Wang ◽  
L.Z. Ding
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Phase Transformation ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Annealing Time ◽  
Figure Of Merit ◽  
Iron Disilicide ◽  
Temperature Range ◽  
Average Grain Size

Iron disilicide (-FeSi2, and -FeSi2+Cu0.1wt%) were prepared by a field-activated pressure assisted synthesis(FAPAS) method from elemental powders and the thermoelectric properties were investigated. The average grain size of these products is about 0.3m. The thermal conductivity of these materials is 3-4wm-1K-1in the temperature range 300-725K. These products’ figure of merit is 28.50×10-4 in the temperature range 330-450K. The additions of Cu promote the phase transformation of -Fe2Si5 + -FeSi → β-FeSi2 and shorten the annealing time. It is proved that FAPAS is a benign and rapid process for sintering of -FeSi2 thermoelectric materials.

Thermoelectric Power Factor of Polycrystalline La0.75Sr0.25Co1-xMnxO3-δCeramics

2009 ◽  
Vol 1166 ◽  
Author(s):  
Julio E. Rodríguez ◽  
J. A. Niño
Keyword(s):  
Transport Properties ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Manganese Content ◽  
Solid State Reaction Method ◽  
Measured Temperature ◽  
Thermoelectric Power Factor ◽  
Temperature Range

AbstractThermoelectric properties of polycrystalline La0.75Sr0.25Co1-xMnxO3-δ(0<x<0.08) (LSCoO-Mn) compounds have been studied. The samples were grown by solid-state reaction method; their transport properties were studied in the temperature range between 100 and 290K, as a function of temperature and the manganese content. The Seebeck coefficient (S) is positive over the measured temperature range and its magnitude increases with the manganese content up to values close to 160 μV/K. The electrical resistivity (ρ) goes from metallic to semiconducting behavior as the Mn level increases, at room temperature, ρ(T) exhibit values less than 4mΩ-cm. From S(T), ρ(T) and κ(T) data, the thermoelectric power factor and the figure of merit were determined. These performance parameters reach maximum values around 18 μW/K2-cm and 0.2, respectively. The observed behavior in the transport properties become these compounds potential thermoelectric materials, which could be used in thermoelectric applications.

Effect of Ni in new skutterudite compounds CaxCo4Sb12

2003 ◽  
Vol 793 ◽  
Author(s):  
Matthieu Puyet ◽  
Bertrand Lenoir ◽  
Anne Dauscher ◽  
Hubert Scherrer ◽  
Moukrane Dehmas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Beneficial Effect ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Positive Influence ◽  
Temperature Range ◽  
Dimensionless Figure Of Merit ◽  
Ni Substitution

ABSTRACTThe transport properties of the partially filled CaxCo4-yNiySb12 skutterudite compounds have been investigated in the 300 – 800 K temperature range. We underline the positive influence of the Ni substitution on the electrical resistivity and thermopower while the thermal properties – thermal conductivity – remains almost unaffected. These results suggest again a beneficial effect of Ni atoms on the dimensionless figure of merit in CoSb3 based compounds.

scholarly journals THERMAL CONDUCTIVITY OF COMPOSITIONS BASED ON A SILOXANE BINDER WITH A HIGH FILLER CONTENT OF ALUMINUM HYDROXIDE POWDER

2018 ◽  
pp. 39-43
Author(s):  
V. Sh. Sulaberidze ◽  
V. D. Mushenko ◽  
V. A. Mikheev
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Aluminum Hydroxide ◽  
Volume Content ◽  
Room Temperature ◽  
Filler Content ◽  
Heat Conducting ◽  
Temperature Range ◽  
Wide Range ◽  
Volumetric Content

The use of aluminum hydroxide as a filler in composite materials makes them non-flammable. When the thermal conductivity of such compositions is above 1 W/(m-K), they can be used as heat-conducting insulating and non-flammable coatings in power electronics. Thermal conductivity of compositions based on dimethylsiloxane with a filler made from aluminum hydroxide powders of various dissipation is studied in the temperature range from 25 °C to 200 °C, depending on the volume content of the filler. With a volumetric content of filler up to 60%, no significant differences in the values of the thermal conductivity of samples with powders of the investigated fractional groups were detected. With volumetric content of the filler more than 40%, the thermal conductivity of the composition at room temperature exceeded 1 W/(m-K). It is shown that the Burger formula modified by the authors turned out to be sufficiently universal for the calculated estimates of the thermal conductivity of materials with different fillers in a wide range of their volume contents.

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