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

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.

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Effect of Al substitution on Thermoelectric Performance of CuInTe2 compounds

MRS Proceedings ◽

10.1557/opl.2015.316 ◽

2015 ◽

Vol 1735 ◽

Cited By ~ 3

Author(s):

Chuandeng Hu ◽

Kunling Peng ◽

Guiwen Wang ◽

Lijie Guo ◽

Guoyu Wang ◽

...

Keyword(s):

Transport Properties ◽

Figure Of Merit ◽

Phonon Scattering ◽

First Principle ◽

Principle Calculation ◽

First Principle Calculation ◽

Al Substitution ◽

Plasma Sintering ◽

Spark Plasma ◽

Grain Surface

ABSTRACTThermoelectric CuIn1-xAlxTe2 compounds (x=0, 0.05, 0.1, 0.15, 0.50) have been synthesized by solid state reaction followed by spark plasma sintering. The influence of Al substitution on electrical and thermal transport properties has been investigated in the CuInTe2 compounds. It was found that the Seebeck coefficient and electrical conductivity is reduced by isovalent replacement of In with Al. Our first principle calculation indicates Al substitution leads to the widen band gap, the reduction in the number of degeneracy of valence band and the effective mass. Furthermore, a large reduction in thermal conductivity is achieved through the enhanced phonon scattering via point defect as well as the nano-sized particles observed between grain boundaries and on the grain surface. In spite of the reduced charge transport properties, an improved figure-of- merit ZT is achieved, reaching 0.8 at 800 K, 33% higher in comparison to the pure CuInTe2 compound.

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Preparation and Thermoelectric Properties of Bi Doped Ca3Co4O9 Based Thermoelectric Materials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.783.144 ◽

2018 ◽

Vol 783 ◽

pp. 144-147

Author(s):

Jing Wang ◽

Qin Chen ◽

Xia Chun Zhu ◽

Seok Je Lee ◽

Kyoung Woo Park ◽

...

Keyword(s):

Thermoelectric Properties ◽

Figure Of Merit ◽

Phonon Scattering ◽

Solid Phase ◽

Solid Phase Reaction ◽

Phase Reaction ◽

Sintering Process ◽

Spin Entropy ◽

Plasma Sintering ◽

Spark Plasma

Polycrystalline Ca3-xBixCo4O9 samples have been prepared by solid-phase reaction followed by spark plasma sintering process. The thermoelectric properties have been systematically investigated from room temperature to near 1000K. It is found that the change of the carrier concentration leads to the change of resistivity, which is mainly associated with doping induced point defect phonon scattering. The change of the thermal potential mainly comes from the spin entropy. In addition, polycrystalline Ca3-xBixCo4O9 had a maximum figure of merit of 0.30 at 973 K, which was about 50% higher than Ca3Co4O9. It indicated that doping approach can effectively improve the thermoelectric performance of Ca3Co4O9+δ-based material.

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Thermoelectric Transport Properties of n-Type Sb-doped (Hf,Zr,Ti)NiSn Half-Heusler Alloys Prepared by Temperature-Regulated Melt Spinning and Spark Plasma Sintering

Applied Sciences ◽

10.3390/app10144963 ◽

2020 ◽

Vol 10 (14) ◽

pp. 4963 ◽

Cited By ~ 1

Author(s):

Ki Wook Bae ◽

Jeong Yun Hwang ◽

Sang-il Kim ◽

Hyung Mo Jeong ◽

Sunuk Kim ◽

...

Keyword(s):

Thermal Conductivity ◽

Spark Plasma Sintering ◽

Figure Of Merit ◽

Melt Spinning ◽

Lattice Thermal Conductivity ◽

Heusler Alloys ◽

Thermoelectric Figure ◽

Plasma Sintering ◽

Thermoelectric Transport Properties ◽

Spark Plasma

Herein we report a significantly reduced lattice thermal conductivity of Sb-doped Hf0.35Zr0.35Ti0.3NiSn half-Heusler alloys with sub-micron grains (grain size of ~300 nm). Polycrystalline bulks of Hf0.35Zr0.35Ti0.3NiSn1−xSbx (x = 0.01, 0.02, 0.03) with a complete single half-Heusler phase are prepared using temperature-regulated melt spinning and subsequent spark plasma sintering without a long annealing process. In these submicron-grained bulks, a very low lattice thermal conductivity value of ~2.4 W m−1 K−1 is obtained at 300 K due to the intensified phonon scatterings by highly dense grain boundaries and point-defects (Zr and Ti substituted at Hf-sites). A maximum thermoelectric figure of merit, zT, of 0.5 at 800 K is obtained in Hf0.35Zr0.35Ti0.3NiSn0.99Sb0.01.

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

Materials ◽

10.3390/ma11112237 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2237 ◽

Cited By ~ 16

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.

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Enhanced thermoelectric properties of N-type polycrystalline In4Se3-x compounds via thermally induced Se deficiency

Functional Materials Letters ◽

10.1142/s1793604714500258 ◽

2014 ◽

Vol 07 (03) ◽

pp. 1450025 ◽

Cited By ~ 2

Author(s):

Ran Zhao ◽

Yu-Tian Shu ◽

Fu Guo

Keyword(s):

Thermoelectric Properties ◽

Thermal History ◽

Thermal Processing ◽

Carrier Mobility ◽

Figure Of Merit ◽

Thermally Induced ◽

Plasma Sintering ◽

Spark Plasma ◽

Se Deficiency ◽

Surface Morphologies

In 4 Se 3-x compound is considered as a potential thermoelectric material due to its comparably low thermal conductivity among all existing ones. While most studies investigated In 4 Se 3-x thermoelectric properties by controlling selennium or other dopants concentrations, in the current study, it was found that even for a fixed initial In / Se ratio, the resulting In / Se ratio varied significantly with different thermal processing histories (i.e., melting and annealing), which also resulted in varied thermoelectric properties as well as fracture surface morphologies of In 4 Se 3-x polycrystalline specimens. Single phase polycrystalline In 4 Se 3-x compounds were synthesized by combining a sequence of melting, annealing, pulverizing, and spark plasma sintering. The extension of previous thermal history was observed to significantly improve the electrical conductivity (about 121%) and figure of merit (about 53%) of In 4 Se 3-x polycrystalline compounds. The extended thermal history resulted in the increase of Se deficiency (x) from 0.39 to 0.53. This thermally induced Se deficiency was observed to associate with increasing carrier mobility but decreasing concentration, which differs from the general trend observed for the initially adjusted Se deficiency at room temperature. Unusually large dispersed grains with nanosize layers were observed in specimens with the longest thermal history. The mechanism(s) by which previous thermal processing enhances carrier mobility and affect microstructural evolution are briefly discussed.

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Extremely Fast and Cheap Densification of Cu2S by Induction Melting Method

Materials ◽

10.3390/ma14237311 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7311

Author(s):

Paweł Nieroda ◽

Krzysztof Ziewiec ◽

Juliusz Leszczyński ◽

Paweł Rutkowski ◽

Andrzej Koleżyński

Keyword(s):

Chemical Composition ◽

Figure Of Merit ◽

Induction Melting ◽

X Ray Diffraction ◽

Temperature Range ◽

Plasma Sintering ◽

Melting Technique ◽

Thermoelectric Transport Properties ◽

Spark Plasma ◽

Phase And Chemical Composition

The aim of this work was to obtain dense Cu2S superionic thermoelectric materials, homogeneous in terms of phase and chemical composition, using a very fast and cheap induction-melting technique. The chemical composition was investigated via scanning electron microscopy (SEM) combined with an energy-dispersive spectroscopy (EDS) method, and the phase composition was established by X-ray diffraction (XRD). The thermoelectric figure of merit ZT was determined on the basis of thermoelectric transport properties, i.e., Seebeck coefficient, electrical and thermal conductivity in the temperature range of 300–923 K. The obtained values of the ZT parameter are comparable with those obtained using the induction hot pressing (IHP) technique and about 30–45% higher in the temperature range of 773–923 K in comparison with Cu2S samples densified with the spark plasma sintering (SPS) technique.

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Thermoelectric Properties of Cu2SnSe3-Based Composites Containing Melt-Spun Cu–Te

Metals ◽

10.3390/met9090971 ◽

2019 ◽

Vol 9 (9) ◽

pp. 971

Author(s):

Degang Zhao ◽

Lin Wang ◽

Di Wu ◽

Lin Bo

Keyword(s):

Thermal Conductivity ◽

Seebeck Coefficient ◽

Carrier Mobility ◽

Figure Of Merit ◽

Melt Spinning ◽

Lattice Thermal Conductivity ◽

Milling Process ◽

Plasma Sintering ◽

Nanocrystalline Structures ◽

Spark Plasma

In this study, the Cu–Te alloy ribbons containing nanocrystalline structures were prepared by melt spinning (MS), and were composed of Cu2−xTe, Cu2Te, Cu3−xTe, and CuTe phases. Crystal grains on both sides of the ribbons were uniformly distributed and the grain size of the contact surface was about 400 nm. The Cu–Te powder was incorporated into the Cu2SnSe3 powder by the ball milling process and the Cu–Te/Cu2SnSe3 thermoelectric composite was prepared by spark plasma sintering (SPS). With the amount of Cu–Te powder increasing, the carrier concentration of the Cu–Te/Cu2SnSe3 composite increased, while the carrier mobility and electrical conductivity initially increased and then decreased. Compared to the Seebeck coefficient of the Cu2SnSe3 matrix, the Seebeck coefficient of the Cu–Te/Cu2SnSe3 samples increased slightly. Moreover, the Cu–Te/Cu2SnSe3 composites had lower thermal conductivity and lattice thermal conductivity over the whole temperature range. The lattice thermal conductivity of the 0.8 vol.% Cu–Te/Cu2SnSe3 composite achieved the lowest value of 0.22 W/m·K, which was 78% lower than that of the Cu2SnSe3 matrix. The maximum figure of merit of the 0.8 vol.% Cu–Te/Cu2SnSe3 composite was 0.45 at 700 K.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.875 ◽

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.

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Thermoelectric Transport Properties of Cu Nanoprecipitates EmbeddedBi2Te2.7Se0.3

Journal of Nanomaterials ◽

10.1155/2015/820893 ◽

2015 ◽

Vol 2015 ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

Eunsil Lee ◽

Jin Il Kim ◽

Soon-Mok Choi ◽

Young Soo Lim ◽

Won-Seon Seo ◽

...

Keyword(s):

Power Factor ◽

Colloidal Suspension ◽

Raw Material ◽

Mixed Powder ◽

Thermoelectric Transport ◽

Plasma Sintering ◽

Thermoelectric Transport Properties ◽

Spark Plasma ◽

Scalable Synthesis ◽

Filtering Effect

We suggest a simple and scalable synthesis to prepare Cu-Bi2Te2.7Se0.3(Cu-BTS) nanocomposites. By precipitating Cu nanoparticle (NP) in colloidal suspension of as-exfoliated BTS, homogeneous mixtures of Cu NP and BTS nanosheet were readily achieved, and then the sintered nanocomposites were fabricated by spark plasma sintering technique using the mixed powder as a raw material. The precipitated Cu NPs in the BTS matrix effectively generated nanograin (BTS) and heterointerface (Cu/BTS) structures. The maximumZTof 0.90 at 400 K, which is 15% higher compared to that of pristine BTS, was obtained in 3 vol% Cu-BTS nanocomposite. The enhancement ofZTresulted from improved power factor by carrier filtering effect due to the Cu nanoprecipitates in the BTS matrix.

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High Temperature Thermoelectric Properties of AgPb18+xSbTe20

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.857 ◽

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.

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