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Title: High-performance Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering

Abstract

Polycrystalline Ag{sub n}Pb{sub m}SbTe{sub m+2n} thermoelectric materials, whose compositions can be described as Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} were prepared using a combined process of mechanical alloying and spark plasma sintering. Electric properties of the sintered samples with different Pb contents were measured from room temperature to 700 K. The maximum power factor of 1.766 mW/mK{sup 2} was obtained at 673 K for the Ag{sub 0.8}Pb{sub 22}SbTe{sub 20} sample, which corresponds to a high dimensionless figure of merit, ZT=1.37. This best composition is different from that reported before.

Authors:
; ; ; ; ; ;  [1];  [2];  [3]
  1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)
  2. (China)
  3. (Japan)
Publication Date:
OSTI Identifier:
20778755
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 9; Other Information: DOI: 10.1063/1.2181197; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIMONY COMPOUNDS; ELECTRICAL PROPERTIES; LEAD COMPOUNDS; PERFORMANCE; PLASMA; POLYCRYSTALS; POWER FACTOR; SILVER COMPOUNDS; SINTERING; TELLURIUM COMPOUNDS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; THERMOELECTRIC MATERIALS; THERMOELECTRICITY

Citation Formats

Wang Heng, Li Jingfeng, Nan Cewen, Zhou Min, Liu Weishu, Zhang Boping, Kita, Takuji, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, and Material Engineering Division III, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193. High-performance Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering. United States: N. p., 2006. Web. doi:10.1063/1.2181197.
Wang Heng, Li Jingfeng, Nan Cewen, Zhou Min, Liu Weishu, Zhang Boping, Kita, Takuji, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, & Material Engineering Division III, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193. High-performance Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering. United States. doi:10.1063/1.2181197.
Wang Heng, Li Jingfeng, Nan Cewen, Zhou Min, Liu Weishu, Zhang Boping, Kita, Takuji, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, and Material Engineering Division III, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193. Mon . "High-performance Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering". United States. doi:10.1063/1.2181197.
@article{osti_20778755,
title = {High-performance Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering},
author = {Wang Heng and Li Jingfeng and Nan Cewen and Zhou Min and Liu Weishu and Zhang Boping and Kita, Takuji and School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 and Material Engineering Division III, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193},
abstractNote = {Polycrystalline Ag{sub n}Pb{sub m}SbTe{sub m+2n} thermoelectric materials, whose compositions can be described as Ag{sub 0.8}Pb{sub 18+x}SbTe{sub 20} were prepared using a combined process of mechanical alloying and spark plasma sintering. Electric properties of the sintered samples with different Pb contents were measured from room temperature to 700 K. The maximum power factor of 1.766 mW/mK{sup 2} was obtained at 673 K for the Ag{sub 0.8}Pb{sub 22}SbTe{sub 20} sample, which corresponds to a high dimensionless figure of merit, ZT=1.37. This best composition is different from that reported before.},
doi = {10.1063/1.2181197},
journal = {Applied Physics Letters},
number = 9,
volume = 88,
place = {United States},
year = {Mon Feb 27 00:00:00 EST 2006},
month = {Mon Feb 27 00:00:00 EST 2006}
}
  • The nanostructuring occurring in the AgPb{sub 18}SbTe{sub 20} system is documented and it is shown to contain coherent or semi-coherent Ag-rich nano-inclusions, most in range of 2 to 30 nm embedded in an essentially PbTe matrix. The analysis of the nanostructuring supports the mechanism believed to be responsible for achieving a high thermoelectric figure-of-merit.
  • Ag-doped n-type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-} {sub x} Ag {sub x} Se{sub 3}){sub 0.1} (x=0-0.4) alloys were prepared by spark plasma sintering and their physical properties evaluated. When at low Ag content (x=0.05), the temperature dependence of the lattice thermal conductivity follows the trend of (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2}Se{sub 3}){sub 0.1}; while at higher Ag content, a relatively rapid reduction above 400 K can be observed due possibly to the enhancement of scattering of phonons by the increased defects. The Seebeck coefficient increases with Ag content, with some loss of electrical conductivity, but the maximum dimensionless figure ofmore » merit ZT can be obtained to be 0.86 for the alloy with x=0.4 at 505 K, about 0.2 higher than that of the alloy (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2}Se{sub 3}){sub 0.1} without Ag-doping. - Graphical abstract: The temperature dependence of dimensionless thermoelectric figure of merit ZT for different (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-} {sub x} Ag {sub x} Se{sub 3}){sub 0.1} (x=0-0.4) alloys prepared by spark plasma sintering.« less
  • In this paper, pseudo-binary (Ag{sub 0.365}Sb{sub 0.558}Te) {sub x} -(Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}){sub 1-} {sub x} (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9x10{sup 4} to 15.6x10{sup 4} {omega}{sup -1} m{sup -1} at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} alloy ismore » 0.58 near room temperature. The results also reveal that a direct introduction of Ag{sub 0.365}Sb{sub 0.558}Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag{sub 0.365}Sb{sub 0.558}Te in the Ag-doped Ag-Bi-Sb-Te system. - Graphical abstract: The temperature dependence of the dimensionless thermoelectric figure of merit ZT for different (Ag{sub 0.365}Sb{sub 0.558}Te) {sub x} -(Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}){sub 1-} {sub x} (x=0-1.0) alloys prepared by spark plasma sintering.« less
  • The gallium composition dependence of crystallographic and thermoelectric properties in polycrystalline n-type Ba{sub 8}Ga{sub x}Si{sub 46-x} (nominal x=14-18) compounds with the type-I clathrate structure is presented. Samples were prepared by combining arc melting and spark plasma sintering methods. Powder x-ray diffraction, Rietveld analysis, scanning electron microscopy, and energy-dispersive x-ray spectroscopy show that the solubility limit of gallium in the type-I clathrate phase is close to x=15, which is slightly higher than that for a single crystal. The carrier concentration at room temperature decreases from 2 Multiplication-Sign 10{sup 21} cm{sup -3} to 4 Multiplication-Sign 10{sup 20} cm{sup -3} as the Gamore » content x increases. The Seebeck coefficient, the electrical conductivity, and the thermal conductivity vary systematically with the carrier concentration when the Ga content x varies. The effective mass (2.0m{sub 0}), the carrier mobility (10 cm{sup 2} V{sup -1} s{sup -1}), and the lattice thermal conductivity (1.1 W m{sup -1} K{sup -1}) are determined for the Ga content x=14.51. The dimensionless thermoelectric figure of merit ZT is about 0.55 at 900 K for the Ga content x=14.51. The calculation of ZT using the experimentally determined material parameters predicts ZT=0.8 (900 K) at the optimum carrier concentration of about 2 Multiplication-Sign 10{sup 20} cm{sup -3}. - Graphical abstract: The gallium composition dependence of crystallographic and thermoelectric properties is presented on polycrystalline n-type Ba{sub 8}Ga{sub x}Si{sub 46-x} with the type-I clathrate structure prepared by combining arc melting and spark plasma sintering methods. The thermoelectric figure of merit ZT reaches 0.55 at 900 K due to the increase in the Ga content (close to x=15), and a calculation predicts further improvement of ZT at the optimized carrier concentration. Highlights: Black-Right-Pointing-Pointer Crystallographic properties of Ba{sub 8}Ga{sub x}Si{sub 46-x} clathrates are characterized. Black-Right-Pointing-Pointer Arc melting and spark plasma sintering process enables increase of Ga content. Black-Right-Pointing-Pointer We elucidate the Ga composition dependence of thermoelectric properties. Black-Right-Pointing-Pointer Thermoelectric figure of merit ZT is improved due to the increased Ga content. Black-Right-Pointing-Pointer Calculation predicts a potential ZT=0.8 at 900 K at optimized carrier concentration.« less
  • This study reports microstructural investigations of long-term annealed Ag{sub 1-x}Pb{sub m}Sb{sub 1+y}Te{sub 2+m} (m=18, x=y=0, hereinafter referred to as AgPb{sub 18}SbTe{sub 20}) (Lead-Antimony-Silver-Tellurium, LAST-18) as well as of Ag{sub 1-x}Pb{sub 18}Sb{sub 1+y}Te{sub 20}, i.e. Ag-deficient and Sb-excess LAST-18 (x{ne}0,y{ne}0), respectively. Two different length scales are explored. The micrometer scale was evaluated by SEM to analyze the volume fraction and the number of secondary phases as well as the impact of processing parameters on the homogeneity of bulk samples. For AgPb{sub 18}SbTe{sub 20}, site-specific FIB liftout of TEM lamellae from thermoelectrically characterized samples was accomplished to investigate the structure on themore » nanometer scale. High-resolution TEM and energy-filtered TEM were performed to reveal shape and size distribution of nanoprecipitates, respectively. A hypothesis concerning the structure-property relationship is set out within the frame of a gradient annealing experiment. This study is completed by results dealing with inhomogeneities on the micrometer scale of Ag{sub 1-x}Pb{sub 18}Sb{sub 1+y}Te{sub 20} and its electronic properties. Highlights: Black-Right-Pointing-Pointer SEM and TEM microstructure investigation of long-term annealed AgPb{sub 18}SbTe{sub 20}. Black-Right-Pointing-Pointer SEM and thermoelectric studies on Ag{sub 1-x}Pb{sub 18}Sb{sub 1+y}Te{sub 20}. Black-Right-Pointing-Pointer Discussion concerning structure-property relationship in long-term annealed AgPb{sub 18}SbTe{sub 20}. Black-Right-Pointing-Pointer Correlation between Ag{sub 1-x}Pb{sub 18}Sb{sub 1+y}Te{sub 20} microscale structure and electronic properties.« less