scholarly journals Detrimental Effects of Doping Al and Ba on the Thermoelectric Performance of GeTe

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2237 ◽  
Author(s):  
Bhuvanesh Srinivasan ◽  
Alain Gellé ◽  
Jean-François Halet ◽  
Catherine Boussard-Pledel ◽  
Bruno Bureau
Keyword(s):  
Carrier Mobility ◽  
Figure Of Merit ◽  
Charge Carrier Concentration ◽  
Energy Separation ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Higher Temperature ◽  
Valence Bands ◽  
P Type

GeTe-based materials are emerging as viable alternatives to toxic PbTe-based thermoelectric materials. In order to evaluate the suitability of Al as dopant in thermoelectric GeTe, a systematic study of thermoelectric properties of Ge1−xAlxTe (x = 0–0.08) alloys processed by Spark Plasma Sintering are presented here. Being isoelectronic to Ge1−xInxTe and Ge1−xGaxTe, which were reported with improved thermoelectric performances in the past, the Ge1−xAlxTe system is particularly focused (studied both experimentally and theoretically). Our results indicate that doping of Al to GeTe causes multiple effects: (i) increase in p-type charge carrier concentration; (ii) decrease in carrier mobility; (iii) reduction in thermopower and power factor; and (iv) suppression of thermal conductivity only at room temperature and not much significant change at higher temperature. First principles calculations reveal that Al-doping increases the energy separation between the two valence bands (loss of band convergence) in GeTe. These factors contribute for Ge1−xAlxTe to exhibit a reduced thermoelectric figure of merit, unlike its In and Ga congeners. Additionally, divalent Ba-doping [Ge1−xBaxTe (x = 0–0.06)] is also studied.

scholarly journals Development of Spark Plasma Syntering (SPS) technology for preparation of nanocrystalline p-type thermoelctrics based on (BiSb)2Te3

2020 ◽  
Vol 21 (4) ◽  
pp. 628-634
Author(s):  
O. Kostyuk ◽  
B. Dzundza ◽  
M. Maksymuk ◽  
V. Bublik ◽  
L. Chernyak ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Antimony Telluride ◽  
Bismuth Antimony Telluride ◽  
Thermoelectric Figure ◽  
Temperature Range ◽  
Plasma Sintering ◽  
Different Temperatures ◽  
Spark Plasma ◽  
P Type

Bismuth antimony telluride is the most commonly used commercial thermoelectric material for power generation and refrigeration over the temperature range of 200–400 K. Improving the performance of these materials is a complected balance of optimizing thermoelectric properties. Decreasing the grain size of Bi0.5Sb1.5Te3 significantly reduces the thermal conductivity due to the scattering phonons on the grain boundaries. In this work, it is shown the advances of spark plasma sintering (SPS) for the preparation of nanocrystalline p-type thermoelectrics based on Bi0.5Sb1.5Te3 at different temperatures (240, 350, 400oC). The complex study of structural and thermoelectric properties of Bi0.5Sb1.5Te3 were presented. The high dimensionless thermoelectric figure of merit ZT ~ 1 or some more over 300–400 K temperature range for nanocrystalline p-type Bi0.5Sb1.5Te3 was obtained.

Thermoelectric Properties of Silicon Germanium Alloy Nanocomposite Fabricated by Mechanical Alloying and Spark Plasma Sintering

2016 ◽  
Vol 703 ◽  
pp. 70-75 ◽  
Author(s):  
Zhen Ye Zhu ◽  
Shi Lei Guo
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Silicon Germanium ◽  
Figure Of Merit ◽  
Thermoelectric Figure ◽  
Long Wavelength ◽  
Plasma Sintering ◽  
Germanium Alloy ◽  
Spark Plasma ◽  
P Type

High dense p-type Si95Ge5 doped with nanoSi70Ge30B5particles thermoelectric materials were firstly fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) method. The effects of different nanoSi70Ge30B5 doping content on the thermoelectric and phase properties were studied. A dimensionless thermoelectric figure-of-merit (ZT) of 0.47 at 710K in p-type nanocomposite bulk silicon germanium (SiGe) alloys is achieved. The enhancement of ZT is due to a large reduction of thermal conductivity caused by the increased grain boundaries of the numerous nanograins that effectively scatter long wavelength phonons.

Significantly enhanced thermoelectric figure of merit of p-type Mg3Sb2-based Zintl phase compounds via nanostructuring and employing high energy mechanical milling coupled with spark plasma sintering

2015 ◽  
Vol 3 (20) ◽  
pp. 10777-10786 ◽  
Author(s):  
A. Bhardwaj ◽  
N. S. Chauhan ◽  
D. K. Misra
Keyword(s):  
Thermoelectric Materials ◽  
Mechanical Milling ◽  
Figure Of Merit ◽  
High Energy ◽  
Thermoelectric Figure Of Merit ◽  
Zintl Phase ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

Several nanostructuring methods have been demonstrated to produce a variety of nanostructured materials, and these methods are well recognized as effective paradigms for improving the performance of thermoelectric materials.

Fabrication of Bi-Te Based Thermoelectric Semiconductors by Using Hybrid Powders

2005 ◽  
Vol 297-300 ◽  
pp. 875-880
Author(s):  
Cheol Ho Lim ◽  
Ki Tae Kim ◽  
Yong Hwan Kim ◽  
Dong Choul Cho ◽  
Young Sup Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Bending Strength ◽  
Mixing Ratio ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

P-type Bi0.5Sb1.5Te3 compounds doped with 3wt% Te were fabricated by spark plasma sintering and their mechanical and thermoelectric properties were investigated. The sintered compounds with the bending strength of more than 50MPa and the figure-of-merit 2.9×10-3/K were obtained by controlling the mixing ratio of large powders (PL) and small powders (PS). Compared with the conventionally prepared single crystal thermoelectric materials, the bending strength was increased up to more than three times and the figure-of-merit Z was similar those of single crystals. It is expected that the mechanical properties could be improved by using hybrid powders without degradation of thermoelectric properties.

scholarly journals Hf-Doping Effect on the Thermoelectric Transport Properties of n-Type Cu0.01Bi2Te2.7Se0.3

2020 ◽  
Vol 10 (14) ◽  
pp. 4875
Author(s):  
Jeong Yun Hwang ◽  
Sura Choi ◽  
Sang-il Kim ◽  
Jae-Hong Lim ◽  
Soon-Mok Choi ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Mass Difference ◽  
Solidification Process ◽  
Transport Parameters ◽  
Plasma Sintering ◽  
Thermoelectric Transport Properties ◽  
Spark Plasma ◽  
Melt Solidification

Polycrystalline bulks of Hf-doped Cu0.01Bi2Te2.7Se0.3 are prepared via a conventional melt-solidification process and subsequent spark plasma sintering technology, and their thermoelectric performances are evaluated. To elucidate the effect of Hf-doping on the thermoelectric properties of n-type Cu0.01Bi2Te2.7Se0.3, electronic and thermal transport parameters are estimated from the measured data. An enlarged density-of-states effective mass (from ~0.92 m0 to ~1.24 m0) is obtained due to the band modification, and the power factor is improved by Hf-doping benefitting from the increase in carrier concentration while retaining carrier mobility. Additionally, lattice thermal conductivity is reduced due to the intensified point defect phonon scattering that originated from the mass difference between Bi and Hf. Resultantly, a peak thermoelectric figure of merit zT of 0.83 is obtained at 320 K for Cu0.01Bi1.925Hf0.075Te2.7Se0.3, which is a ~12% enhancement compared to that of the pristine Cu0.01Bi2Te2.7Se0.3.

High Temperature Thermoelectric Properties of AgPb18+xSbTe20

2007 ◽  
Vol 336-338 ◽  
pp. 857-859
Author(s):  
Wen Bing Zhang ◽  
Li Dong Chen ◽  
Xiao Ya Li
Keyword(s):  
Crystal Structure ◽  
Figure Of Merit ◽  
Lead Telluride ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Pure Lead ◽  
Melting Method ◽  
Temperature Range ◽  
Plasma Sintering ◽  
Spark Plasma

Polycrystalline AgPb18+xSbTe20 compounds with different Pb contents (x=1-4) were prepared by melting method and spark plasma sintering techniques. The crystal structure and chemical composition were determined by XRD and EPMA. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured in the temperature range of 300-800K. The dimensionless thermoelectric figure of merit (ZT) of AgPb18+xSbTe20 (x=1-4) increases in the whole temperature range of 300-750K which is different to the pure lead telluride compound. The maximum ZT value reaches 1.03 at 800K.

scholarly journals Nanostructured SiGe:Sb solid solutions with improved thermoelectric figure of merit

2020 ◽  
Author(s):  
Mikhail Vladimirovich Dorokhin ◽  
Polina Borisovna Demina ◽  
Irina Viktorovna Erofeeva ◽  
Yuri Mikhailovich Kuznetsov ◽  
Anton Vladimirovich Zdoroveyshchev ◽  
...  
Keyword(s):  
Solid State ◽  
Figure Of Merit ◽  
Heating Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Solid State Sintering ◽  
Maximum Heating Temperature ◽  
Spark Plasma ◽  
Maximum Heating

Abstract Thermoelectric Si 0,65 Ge 0,35 Sb δ materials have been fabricated by spark plasma sintering of Ge-Si-Sb powder mixture. The electronic properties of Si 0,65 Ge 0,35 Sb δ were found to be dependent on the uniformity of mixing of the components, which in turn is determined by the maximum heating temperature during solid-state sintering. Provided the concentration of donor Sb impurity is optimized the thermoelectric figure of merit for the investigated structures can be as high as 0.628 at the temperature of 490 °С, the latter value is comparable with world-known analogues obtained for Si 1- x Ge x P δ .

Synthesis and Thermoelectric Properties of WO3/Cu2SnSe3 Composites

2018 ◽  
Vol 913 ◽  
pp. 811-817 ◽  
Author(s):  
Di Wu ◽  
Ji Ai Ning ◽  
De Gang Zhao ◽  
Xue Zhen Wang ◽  
Na Liu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Figure Of Merit ◽  
Milling Process ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma

In this study, nanometer WO3 powder was uniformly dispersed into the Cu2SnSe3 powder by ball milling process, and the WO3/Cu2SnSe3 thermoelectric composite was prepared by spark plasma sintering (SPS). The results showed that the nano-WO3 particles were mainly distributed in the grain boundary of Cu2SnSe3 matrix, and the grain growth of Cu2SnSe3 was inhibited. The addition of nano-WO3 could enhance the electrical conductivity of Cu2SnSe3, and while the Seebeck coefficient increased slightly for the 0.4% WO3/Cu2SnSe3 composite. The thermal conductivity was not decreased until the content of WO3 exceeded 1.6%. The highest thermoelectric figure of merit ZT of 0.177 was achieved at 700 K for 0.4% WO3/Cu2SnSe3 composite. The enhancement of ZT value of WO3/Cu2SnSe3 thermoelectric material was mainly attributed to the improvement of the electrical properties.

scholarly journals Легирование термоэлектрических материалов на основе твeрдых растворов SiGe в процессе их синтеза методом электроимпульсного плазменного спекания

2019 ◽  
Vol 53 (9) ◽  
pp. 1182
Author(s):  
М.В. Дорохин ◽  
П.Б. Демина ◽  
И.В. Ерофеева ◽  
А.В. Здоровейщев ◽  
Ю.М. Кузнецов ◽  
...  
Keyword(s):  
Solid Solution ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Sintering Process ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Sb Doping ◽  
Spark Plasma ◽  
Large Clusters

AbstractThe results of investigation of thermoelectric materials fabricated by spark plasma sintering and based on Si_1 –_ x Ge_ x solid solutions doped with Sb to a concentration of 0–5 at % are presented. It was found that, at Sb concentration below 1 at %, efficient doping of the solid solution was carried out during the sintering process, which allowed us to form a thermoelectric material with a relatively high thermoelectric figure of merit. An increase in the concentration of antimony in the range of 1–5 at % led to a change in the mechanism of doping, which resulted in an increase in the resistance of materials and the segregation of Sb into large clusters. For such materials, a significant decrease in the Seebeck coefficient and thermoelectric figure of merit was noted. The highest obtained thermoelectric figure of merit (ZT) with Sb doping was 0.32 at 350°C, which is comparable with known analogues for the Ge_ x Si_1 –_ x solid solution.

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