Grain size optimization for high-performance polycrystalline SnSe thermoelectrics

2017 ◽  
Vol 5 (27) ◽  
pp. 14053-14060 ◽  
Author(s):  
Kunling Peng ◽  
Hong Wu ◽  
YanCi Yan ◽  
Lijie Guo ◽  
Guoyu Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
High Performance ◽  
Amorphous Layer ◽  
Thermoelectric Performance ◽  
Size Optimization ◽  
Measured Temperature ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Average Grain Size ◽  
The Stability

Grain size significantly affects the thermoelectric performance, the thickness of oxidized/amorphous layer and the stability of SnSe polycrystals. As a result, sample Sn0.97Na0.03Se with average grain size around 4 μm achieves a high thermoelectric performance and stability in the whole measured temperature range.

Thermoelectric Properties of Doped Iron Disilicide

2000 ◽  
Vol 626 ◽  
Author(s):  
Jun-ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Measured Temperature Range ◽  
Temperature Range

ABSTRACTIn order to investigate the thermoelectric properties of Re-doped β-FeSi2 (Fe1-xRexSi2), Ir-doped β-FeSi2 (Fe1-xIrxSi2), and Pt-doped β-FeSi2 (Fe1-xPtxSi2), the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of these samples have been measured in the temperature range between 300 and 1150 K. Fe1-xRexSi2 is p-type, while Fe1-xIrxSi2 and Fe1-xPt xSi2 are n-type over the measured temperature range. The solubility limits of dopant are estimated to be 0.2at% for Fe1-xRexSi2, 0.5at% for Fe1-xIrxSi2, and 1.9at% for Fe1-xPtxSi2. A maximum ZT value of 0.14 was obtained for Fe1-xPt xSi2 (x=0.03) at the temperature 847 K.

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.

scholarly journals Effect of Content and Size of Reinforcements on the Grain Evolution of Graphene-Reinforced Aluminum Matrix Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2550
Author(s):  
Qi Wu ◽  
Pengfei Cai ◽  
Lianchun Long
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
High Performance ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Pinning Effect ◽  
High Temperature Processes ◽  
Average Grain Size ◽  
Size And Morphology

Graphene-reinforced aluminum matrix composites (GRAMCs) attract great interest in industries due to their high performance potential. High-temperature processes such as sintering and aging are usually applied during the preparation of GRAMCs, leading to grain coarsening that significantly influences its properties. In this work, a modified 3D Monte Carlo Potts model was proposed to investigate the effect of content and size of graphene on the grain evolution during the heat treatment of GRAMCs. Grain growth with graphene contents from 0.5 wt.% to 4.5 wt.% and sizes from 5 μm to 15 μm were simulated. The grain growth process, final grain size and morphology of the microstructure were predicted. The results indicated that both the content and size of the reinforcements had an impact on the grain evolution. The pinning effect of grain size can be enhanced by increasing the content and decreasing the size of graphene. Agglomeration and self-contacting phenomena of the graphene arose obviously when the contents and sizes were relatively high. The average grain size decreased by 48.77% when the content increased from 0.5 wt.% to 4.5 wt.%. The proposed method and predicted regulations can provide a reference for the design and fabrication of GRAMCs.

High-Temperature Acoustical and Electrical Properties of LGS, LGT and CTGS Resonators

2015 ◽  
Vol 230 ◽  
pp. 267-272 ◽  
Author(s):  
Yuriy Suhak ◽  
Michal Schulz ◽  
Denny Richter ◽  
Holger Fritze
Keyword(s):  
Electrical Conductivity ◽  
Bulk Acoustic Wave ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Acoustic Characteristics ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Melting Temperatures ◽  
Acoustic Wave Resonators ◽  
Bulk Acoustic Wave Resonators

Acoustic characteristics and electrical conductivity of CTGS, LGT and LGS bulk acoustic wave resonators operated at the fundamental mode in the temperature range of 20-1470°C are studied. It is shown that LGS and CTGS resonators can be excited piezoelectrically up to 1470 and 1270°C, respectively, which is close to their melting temperatures. The electrical conductivity of CTGS is found to be by at least two and three orders of magnitude lower than that of LGS and LGT, respectively, over the temperature range 400-1000°C. Measurements of temperature dependent electromechanical losses show, that they are at least by two orders of magnitude lower in CTGS comparing to that in LGS within the measured temperature range.

Optical and Microwave Dielectric Properties of Transparent MgAl2O4 Ceramics

2013 ◽  
Vol 647 ◽  
pp. 758-761
Author(s):  
Ping Fu ◽  
Wen Zhong Lu ◽  
Wen Lei ◽  
Yong Xu ◽  
Xian Long Lu
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Spark Plasma Sintering ◽  
Microwave Dielectric Properties ◽  
Temperature Range ◽  
Microwave Dielectric ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Sintering Processes

Transparent polycrystalline MgAl2O4ceramics were fabricated by using spark plasma sintering (SPS) technique at a temperature range from 1275 °C to 1400 °C. The average grain size of the samples fabricated at optimal sintering processes was 345 nm. The in-line transmittance of the sintered ceramics can be as high as 70% at 550 nm and 82% at 2000 nm, respectively. The optimal microwave dielectric properties (εr = 8.38, Q×f = 54000 GHz and τf = -74 ppm/°C) were achieved at 1325°C for 20 min.

scholarly journals Size-dependent density of zirconia nanoparticles

2015 ◽  
Vol 6 ◽  
pp. 27-35 ◽  
Author(s):  
Agnieszka Opalinska ◽  
Iwona Malka ◽  
Wojciech Dzwolak ◽  
Tadeusz Chudoba ◽  
Adam Presz ◽  
...  
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydrothermal Process ◽  
Amorphous Layer ◽  
Average Density ◽  
Size Dependent ◽  
Average Grain Size

The correlation between density and specific surface area of ZrO2 nanoparticles (NPs) was studied. The NPs were produced using a hydrothermal process involving microwave heating. The material was annealed at 1100 °C which resulted in an increase in the average grain size of the ZrO2 NPs from 11 to 78 nm and a decrease in the specific surface area from 97 to 15 m2/g. At the same time, the density increased from 5.22 g/m3 to 5.87 g/m3. This effect was interpreted to be the result of the presence of a hydroxide monolayer on the NP surface. A smaller ZrO2 grain size was correlated with a larger contribution of the low density surface layer to the average density. To prove the existence of such a layer, the material was synthesized using 50% heavy water. Fourier transform infrared spectroscopy (FTIR) permitted the identification of the –OD groups created during synthesis. It was found that the –OD groups persisted on the ZrO2 surface even after annealing at 1100 °C. This hydroxide layer is responsible for the decrease in the average density of the NPs as their size decreases. This study of the correlation between particle size and density may be used to assess the quality of the NPs. In most cases, the technological aim is to avoid an amorphous layer and to obtain fully crystalline nanoparticles with the highest density possible. However, due to the effect of the surface layers, there is a maximum density which can be achieved for a given average NP diameter. The effect of the surface layer on the NP density becomes particularly evident for NPs smaller than 50 nm, and thus, the density of nanoparticles is size dependent.

Microstructure and Magnetic Properties of Nd4.5Fe(76.5-x)B18.5Cu0.5Zrx Nanocomposite Permanent Magnetic Alloys

2007 ◽  
Vol 121-123 ◽  
pp. 1277-1280 ◽  
Author(s):  
Y. Qiao ◽  
Mao Cai Zhang ◽  
J. Zhu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Exchange Coupling ◽  
High Performance ◽  
Magnetic Phase ◽  
Soft Magnetic ◽  
Phase Component ◽  
Average Grain Size ◽  
The Difference ◽  
Microstructure And Magnetic Properties

Nanocomposite Nd2Fe14B/Fe3B magnetic materials with high performance have been obtained by crystallizing over-quenched ribbons. The effect of addition element of Cu and Zr on the phase component, microstructure and magnetic properties of Nd4.5Fe（76.5-x）B18.5Cu0.5Zrx (x= 0.4, 0.5, 1.5, 2.0, 3.0, 4.0) has been systematically investigated. The average grain size of Nd2Fe14B phase and Fe3B phase for the different compositions were calculated from X-day diffraction pattern, which are in accordance with TEM micrographs. For the Nd4.5Fe77B18.5 ribbons, the average grain size of Nd2Fe14B and Fe3B were 34.2 nm and 51.7 nm, and for the Nd4.5Fe76.3B18.5Cu0.5Zr0.4 ribbons, they were only 36.5 nm and 37.1 nm, respectively. It has been found that the additions of Cu and Zr cause the reduction of the difference of grain size between the hard magnetic phase and the soft magnetic phase, that increase the exchange coupling between them. Therefore, it would lead to the magnetic properties improvement. It has been determined that Nd4.5Fe76.3B18.5Cu0.5Zr0.4 was the optimal composition, and the optimal magnetic properties were: Br= 1.204 T, Hci= 271 kA/m, and (BH)max =111.2 kJ/m3.

Excitation and Relaxation Processes of Impact Excitation Emission of Er3+ Ions in InP

1993 ◽  
Vol 301 ◽  
Author(s):  
T. Kimura ◽  
H. Ishida ◽  
S. Yugo ◽  
R. Saito ◽  
H. Isshiki ◽  
...  
Keyword(s):  
Thermal Quenching ◽  
Decay Process ◽  
Impact Excitation ◽  
Relaxation Processes ◽  
Measured Temperature ◽  
Time Decay ◽  
Time Resolved ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
The Impact

ABSTRACTTime-resolved excitation and relaxation processes of the impact excitation emission (EL) at 1.54μm of Er3+ ions doped in InP were investigated in the temperature range from 77K to 330K. The decay process was almost exponential in all the measured temperature range and showed little thermal quenching. The decay time of 2ms at 77K decreased only to tms at 330K. This result contrasted with the large thermal quenching and nonexponential characteristics of the photoluminescence (PL) time decay at higher temperatures, suggesting different Er3+ centers excited between EL and PL. A two-emission-center model is proposed and the different behaviors of thermal quenching and time decay between EL and PL emissions are consistently explained.

Thermoelectric Properties of the Nanostructured NaPb18-xSnxMTe20 (M=Sb, Bi) Materials

2007 ◽  
Vol 1044 ◽  
Author(s):  
Aurelie Gueguen ◽  
Pierre Ferdinand Poudeu Poudeu ◽  
Robert Pcionek ◽  
Huijun Kong ◽  
Ctirad Uher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Measured Temperature ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Properties Of Materials ◽  
P Type

AbstractThe thermoelectric properties of materials with compositions NaPb18-xSnxMTe20 (M=Sb, Bi, x=0, 3, 5, 9, 13, 16 and 18) were investigated in the temperature range 300-670K. All compositions exhibited p-type behavior over the measured temperature range. Electronic properties and transport were tuned through the manipulation of the Pb/Sn ratio. Increasing the Sn fraction results in an increase in electrical conductivity and a decrease in thermopower. The compositions NaPb13Sn5SbTe20 and NaPb9Sn9SbTe20 show a lattice thermal conductivity of ∼1 W/m/K at room temperature.

Dopant Diffusion and Grain Growth in Arsenic-Implanted Poly-Si

1987 ◽  
Vol 106 ◽  
Author(s):  
L. R. Zheng ◽  
L. S. Hung ◽  
J. W. Mayer
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Amorphous Layer ◽  
Crystal Nucleation ◽  
Initial Size ◽  
Diffusion Behavior ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Si Films

ABSTRACTThe diffusion behavior of arsenic and the grain growth of Si in arsenic doped poly-Si were investigated by MeV4 He2+ backscattering techniques and transmission electron microscopy. By implanting arsenic ions into poly-Si films the surface portion was made amorphous and crystallized upon annealing. In-situ mssurements showed crystal nucleation and growth at temperatures of 650 – 700° C with a dimension comparable to the thickness of the amorphous layer. Annealing at temperatures up to 850°C increased the number of the large grains, but the average grain size did not change significantly. In the unimplanted region grains retained their initial size until 885°C, although implanted arsenic was found to diffuse into this region along grain boundaries. At 885°C penetration of arsenic into the interior of grains caused significant grain growth. We also found that single implants of boron somewhat increased grain size, whereas boron codoped with arsenic appeared to reduce the effect of arsenic doping. These observations support the hypothesis that the enhanced growth rate and the electrical activity of Si near the grain boundary are closely interrelated.

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