Phase Purity and Thermoelectric Properties of Type-I Clathrates Ba8CuxSiyGe46-x-y (4 ≤ x ≤ 6.5, y = 0 and 5.15 ≤ x ≤ 6.425, 2.05≤ y ≤ 36.9)

2017 ◽  
Vol 1142 ◽  
pp. 37-44
Author(s):  
Yue Dong ◽  
Xin Lin Yan ◽  
Zhao Hui Tang ◽  
Xue Yong Ding ◽  
Xu Dong Sun ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Ball Milling ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Type I ◽  
Phase Purity ◽  
Arc Melting ◽  
Elemental Substitution ◽  
Plasma Sintering ◽  
Spark Plasma

Type-I clathrates have been considered as very promising thermoelectric (TE) materials thus attracting attention widely. Here we report new clathrates Ba8CuxSiyGe46-x-y (4≤ x ≤ 6.5, y = 0 and 5.15 ≤ x ≤ 6.425, 2.05≤ y ≤ 36.9), focusing on their phase purity and TE properties. Our results show that samples prepared by arc melting followed by annealing are multi-phases alloys. The composition of the clathrate phase is also inhomogeneous. This indicates that the kinetic factor dominates the reaction of forming the clathrate phase during element-melting and sample-annealing. We select three compositions in these two series of samples, which have less impurity and better composition homogeneity for the clathrate phase, and the annealed alloys are furthered processed by ball milling (BM) and powder-solidification (either by hot pressing (HP) or by spark plasma sintering (SPS)) for TE properties investigations. The BM and HP/SPS processes can improve the phase purity and homogeneity. The TE measurements show that the Si-substituted samples have better performance than the Ge-based sample, mainly by decreasing the electrical resistivity. This indicates that the elemental substitution may be still an effective way to improve the TE performance of clathrates.

scholarly journals Synthesis and Thermoelectric Properties of C60/Cu2GeSe3Composites

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Degang Zhao ◽  
Jiai Ning ◽  
Shuyu Li ◽  
Min Zuo
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Grain Boundaries ◽  
Ball Milling ◽  
Thermoelectric Properties ◽  
Phonon Scattering ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Average Size

Nanosized C60powder was sufficiently incorporated with Cu2GeSe3powder by ball milling and C60/Cu2GeSe3composites were prepared by spark plasma sintering. C60distributed uniformly in the form of clusters and the average size of cluster was lower than 1 μm. With the addition of C60increasing, the electrical resistivity and Seebeck coefficient of C60/Cu2GeSe3composites increased while the thermal conductivity decreased significantly which resulted from the phonon scattering by C60clusters locating on the grain boundaries of Cu2GeSe3matrix. The maximumZTof 0.20 was achieved at 700 K for 0.9% C60/Cu2GeSe3sample.

Fabrication and Thermoelectric Properties of Magneli Phases by Adding Ti into TiO2

2011 ◽  
Vol 415-417 ◽  
pp. 1291-1296 ◽  
Author(s):  
Yun Lu ◽  
Yusuke Matsuda ◽  
Katsuhiro Sagara ◽  
Liang Hao ◽  
Takahito Otomitsu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Thermoelectric Performance ◽  
Mixed Powder ◽  
Magnéli Phases ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Ti Powder ◽  
Ti Addition

In the present study, the TiO2-Ti compacts with Magneli phases TinO2n-1 were fabricated using the mixed powder of TiO2 powder and addition Ti powder by spark plasma sintering (SPS). The composition and the crystal types of Magneli phases TinO2n-1 were examined. The results showed that various Magneli phases TinO2n-1 (single or multi Magneli phases) with the composition of Ti1+yO2-x were obtained. The Magneli phases TinO2n-1 were formed in the transformation from the mother phase rutile TiO2 to TiO with increase in Ti addition fraction. In addition, the thermoelectric properties of the sintered compacts were also measured. The electrical resistivity of the sintered compacts decreased with increase in Ti addition fraction. The thermoelectric performance of the sintered compacts was improved by the formation of Magneli phases TinO2n-1 with the composition of Ti1+yO2-x.

Effect of Oxygen Content on Thermoelectric Properties of Sintered Bi-Te Based Compounds

2004 ◽  
Vol 449-452 ◽  
pp. 905-908 ◽  
Author(s):  
Dong Choul Cho ◽  
Cheol Ho Lim ◽  
D.M. Lee ◽  
Seung Y. Shin ◽  
Chung Hyo Lee
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Oxygen Content ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Air Atmosphere ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Effect Of Oxygen

The n-type thermoelectric materials of Bi2Te2.7Se0.3 doped with SbI3 were prepared by spark plasma sintering technique. The powders were ball-milled in an argon and air atmosphere. Then, powders were reduced in H2 atmosphere. Effects of oxygen content on the thermoelectric properties of Bi2Te2.7Se0.3 compounds have been investigated. Seebeck coefficient, electrical resistivity and thermal conductivity of the sintered compound were measured at room temperature. It was found that the effect of atmosphere during the powder production was remarkable and thermoelectric properties of sintered compound were remarkably improved by H2 reduction of starting powder. The obtained maximum figure of merit was 2.4 x 10-3/K.

scholarly journals Thermal and Electronic Transport Properties of the Half-Heusler Phase ScNiSb

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1723 ◽  
Author(s):  
Karol Synoradzki ◽  
Kamil Ciesielski ◽  
Igor Veremchuk ◽  
Horst Borrmann ◽  
Przemysław Skokowski ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Small Magnitude ◽  
Single Phase Sample ◽  
Heusler Phase ◽  
Temperature Range ◽  
Arc Melting ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

Thermoelectric properties of the half-Heusler phase ScNiSb (space group F 4 ¯ 3m) were studied on a polycrystalline single-phase sample obtained by arc-melting and spark-plasma-sintering techniques. Measurements of the thermopower, electrical resistivity, and thermal conductivity were performed in the wide temperature range 2–950 K. The material appeared as a p-type conductor, with a fairly large, positive Seebeck coefficient of about 240 μV K−1 near 450 K. Nevertheless, the measured electrical resistivity values were relatively high (83 μΩm at 350 K), resulting in a rather small magnitude of the power factor (less than 1 × 10−3 W m−1 K−2) in the temperature range examined. Furthermore, the thermal conductivity was high, with a local minimum of about 6 W m−1 K−1 occurring near 600 K. As a result, the dimensionless thermoelectric figure of merit showed a maximum of 0.1 at 810 K. This work suggests that ScNiSb could be a promising base compound for obtaining thermoelectric materials for energy conversion at high temperatures.

Thermoelectric properties of higher manganese silicide/multi-walled carbon nanotube composites

2014 ◽  
Vol 43 (40) ◽  
pp. 15092-15097 ◽  
Author(s):  
D. Y. Nhi Truong ◽  
Holger Kleinke ◽  
Franck Gascoin
Keyword(s):  
Carbon Nanotube ◽  
Thermal Diffusivity ◽  
Ball Milling ◽  
Thermoelectric Properties ◽  
Plasma Sintering ◽  
Multi Walled Carbon Nanotube ◽  
Nanotube Composites ◽  
Manganese Silicide ◽  
Spark Plasma ◽  
Carbon Nanotube Composites

Significant thermal diffusivity reduction in HMS/MWCNT composites prepared by ball milling and spark plasma sintering.

Investigation of thermoelectric properties of Cu2GaxSn1−xSe3 diamond-like compounds by hot pressing and spark plasma sintering

2013 ◽  
Vol 61 (11) ◽  
pp. 4297-4304 ◽  
Author(s):  
Jing Fan ◽  
Huili Liu ◽  
Xiaoya Shi ◽  
Shengqiang Bai ◽  
Xun Shi ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Plasma Sintering ◽  
Spark Plasma

Improvement in the Thermoelectric Properties by Ag/Sb Co-Substitution in PbSe

2012 ◽  
Vol 519 ◽  
pp. 179-183 ◽  
Author(s):  
Jun Qin Li ◽  
X.X. Li ◽  
S.P. Li ◽  
L. Wang ◽  
F.S. Liu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Secondary Phase ◽  
Xrd Analysis ◽  
High Electrical Resistivity ◽  
Plasma Sintering ◽  
Type Semiconductor ◽  
Sb Doping ◽  
Spark Plasma ◽  
Type Conduction

The thermoelectric properties of Ag-doped and Ag/Sb codoped PbSe, prepared by furnace melting, quenching, ball milling and spark plasma sintering (SPS) techniques, were investigated. The X-ray diffraction (XRD) analysis indicated that all samples crystallize in the NaCl-type structure without noticeable secondary phase. The substitution of Ag1+ ion for Pb2+ ion in PbSe caused the compound changed from n-type semiconductor to p-type semiconductor. The lower Ag doped sample Pb1-xAgxSe with x = 0.002 remains n-type conduction of PbSe, shows high electrical resistivity and thus low figure of merit (ZT). However, the higher Ag doped samples Pb1-xAgxSe with x = 0.004, 0.006, 0.008 exhibit n-type conduction, low electrical resistivity and thus leads to the higher ZT. The maximum ZT of the alloy Pb0.996Ag0.004Se reaches 0.66 at 673K, much higher than 0.24 of PbSe at the same temperature. A proper Sb doping in the n-type semiconductor Pb0.998Ag0.002Se can remain its n-type semiconductor, modify the carrier concentration, decrease the electrical resistivity and thus enhance the thermoelectric property. The alloy Sb0.002Pb0.998Ag0.002Se shows a ZT value of 0.59 at 573K, much higher than 0.26 of the sample Pb0.998Ag0.002Se at the same temperature.

Thermoelectric Properties of La-doped BaSi2 and (Ba,Sr)Si2 Solid Solutions

2007 ◽  
Vol 1044 ◽  
Author(s):  
Kohsuke Hashimoto ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
La Doped

AbstractWe studied the thermoelectric properties of BaSi2 and SrSi2. The polycrystalline samples were prepared by spark plasma sintering (SPS). The electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) were measured above room temperature. The maximum values of the dimensionless figure of merit (ZT) were 0.01 at 954 K for BaSi2 and 0.09 at 417 K for SrSi2. We tried to enhance the ZT values of BaSi2 and SrSi2 by prepareing and characterizing La-doped BaSi2 and (Ba,Sr)Si2 solid solution.

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