scholarly journals Influence of Cu Doping on Bipolar Conduction Suppression for p-type Bi0.5Sb1.5Te3 and Bi0.4Sb1.6Te3 Alloys

2020 ◽  
Vol 58 (6) ◽  
pp. 439-445
Author(s):  
Hyun-Jun Cho ◽  
Hyun-Sik Kim ◽  
Woong-hee Sohn ◽  
Sang-il Kim
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Hole Concentration ◽  
Band Model ◽  
Cu Doping ◽  
Conduction Bands ◽  
P Type ◽  
Bipolar Conduction ◽  
Additional Point

In this study, we report how Cu doping can modify the thermoelectric performance of p-type Bi0.5Sb1.5Te3 and Bi0.4Sb1.6Te3 thermoelectric alloys, including their electronic and thermal transport properties. For electronic transport, the power factors of both Bi0.5Sb1.5Te3 and Bi0.4Sb1.6Te3 compositions were increased by Cu doping. The origins of the enhanced power factors were examined using a single parabolic band model, by estimating the changes in deformation potential, effective mass, nondegenerate mobility and weighted mobility in both valence and conduction bands. The weighted mobility of the valence band was increased by Cu doping and increased Sb ratio, while the weighted mobility of the conduction band decreased, suggesting bipolar conduction was greatly reduced. For thermal transport, Cu0.0075Bi0.4Sb1.6Te3 and Bi0.4Sb1.6Te3 had a lower lattice thermal conductivity than Cu0.0075Bi0.5Sb1.5Te3 and Bi0.5Sb1.5Te3, respectively, due to an increase in Umklapp scattering. In addition, Cu doping suppressed bipolar thermal conductivity at high temperatures, by increasing hole concentration. It was also confirmed that Cu-doped samples had a lower lattice thermal conductivity than undoped samples due to additional point defect scattering. As a result, the thermoelectric figure of merit (zT) was greatly enhanced by 0.0075 mol of Cu doping, from 0.80 to 1.11 in Bi0.5Sb1.5Te3, while the zT is increased from 1.0 to 1.05 for Bi0.4Sb1.6Te3.

scholarly journals Reduced Bipolar Conduction in Bandgap-Engineered n-Type Cu0.008Bi2(Te,Se)3 by Sulfur Doping

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 337 ◽  
Author(s):  
Weon Ho Shin ◽  
Hyun-Sik Kim ◽  
Se Yun Kim ◽  
Sung-sil Choo ◽  
Seok-won Hong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperatures ◽  
Figure Of Merit ◽  
Carrier Transport ◽  
Lattice Thermal Conductivity ◽  
Total Thermal Conductivity ◽  
Seebeck Coefficients ◽  
Bipolar Conduction ◽  
Additional Point ◽  
Carrier Transport Properties

Significant bipolar conduction of the carriers in Bi2Te3-based alloys occurs at high temperatures due to their narrow bandgaps. Therefore, at high temperatures, their Seebeck coefficients decrease, the bipolar thermal conductivities rapidly increase, and the thermoelectric figure of merit, zT, rapidly decreases. In this study, band modification of n-type Cu0.008Bi2(Te,Se)3 alloys by sulfur (S) doping, which could widen the bandgap, is investigated regarding carrier transport properties and bipolar thermal conductivity. The increase in bandgap by S doping is demonstrated by the Goldsmid–Sharp estimation. The bipolar conduction reduction is shown in the carrier transport characteristics and thermal conductivity. In addition, S doping induces an additional point-defect scattering of phonons, which decreases the lattice thermal conductivity. Thus, the total thermal conductivity of the S-doped sample is reduced. Despite the reduced power factor due to the unfavorable change in the conduction band, zT at high temperatures is increased by S doping with simultaneous reductions in bipolar and lattice thermal conductivity.

scholarly journals Formation of Dense Pore Structure by Te Addition in Bi0.5Sb1.5Te3: An Approach to Minimize Lattice Thermal Conductivity

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Syed Waqar Hasan ◽  
Hyeona Mun ◽  
Sang Il Kim ◽  
Jung Young Cho ◽  
Jong Wook Roh ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Transport Properties ◽  
Power Factor ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Synergetic Effects ◽  
Spark Plasma ◽  
P Type

We herein report the electronic and thermal transport properties of p-type Bi0.5Sb1.5Te3polycrystalline bulks with dense pore structure. Dense pore structure was fabricated by vaporization of residual Te during the pressureless annealing of spark plasma sintered bulks of Te coated Bi0.5Sb1.5Te3powders. The lattice thermal conductivity was effectively reduced to the value of 0.35 W m−1 K−1at 300 K mainly due to the phonon scattering by pores, while the power factor was not significantly affected. An enhancedZTof 1.24 at 300 K was obtained in spark plasma sintered and annealed bulks of 3 wt.% Te coated Bi0.5Sb1.5Te3by these synergetic effects.

Effects of Ce filling fraction and Fe content on the thermoelectric properties of Co-rich CeyFexCo4−xSb12

2001 ◽  
Vol 16 (3) ◽  
pp. 837-843 ◽  
Author(s):  
Xinfeng Tang ◽  
Lidong Chen ◽  
Takashi Goto ◽  
Toshio Hirai
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Hole Concentration ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Filling Fraction ◽  
Fe Content

Single-phase filled skutterudite compounds, CeyFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of CeyFexCo4−xSb12 were investigated. The lattice thermal conductivity of Ce-saturated CeyFexCo4−xSb12, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Cey Fe1.5Co2.5Sb12 decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce0.28Fe1.52Co2.48Sb12.

scholarly journals Study of anisotropic thermal conductivity in textured thermoelectric alloys by Raman spectroscopy

RSC Advances ◽  
2021 ◽  
Vol 11 (39) ◽  
pp. 24456-24465
Author(s):  
Rapaka S. C. Bose ◽  
K. Ramesh
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Transport Properties ◽  
Thermal Transport ◽  
Layered Crystal ◽  
Layered Crystal Structure ◽  
Thermal Transport Properties ◽  
Anisotropic Thermal Conductivity ◽  
P Type

Polycrystalline p-type Sb1.5Bi0.5Te3 (SBT) and n-type Bi2Te2.7Se0.3 (BTS) compounds possessing layered crystal structure show anisotropic electronic and thermal transport properties.

scholarly journals Investigation of spray pyrolyzed cubic structured Cu doped SnS films

2021 ◽  
Author(s):  
Emrah SARICA
Keyword(s):  
Spray Pyrolysis Technique ◽  
Hole Concentration ◽  
Compressive Strain ◽  
Cubic Phase ◽  
Cu Doping ◽  
Glass Substrates ◽  
High Electrical Resistivity ◽  
Hall Effect Measurements ◽  
P Type ◽  
Deposited Films

Abstract In this work undoped and Cu doped SnS film at 4% and 8% were deposited onto glass substrates by spray pyrolysis technique in order to investigate the effect of Cu doping on their physical properties. Surface investigations showed that Cu doping reduced the surface roughness of SnS films from 36.5 nm to 8.8 nm. XRD studies revealed that all films have recently solved large cubic phase of SnS (p-SnS) with a- lattice of 11.53 Å and Cu doping led to reduction in crystallite size from 229 Å to 198 Å. Additionally, all deposited films were found to be under compressive strain. Optical band gaps of SnS:Cu varied in the range of 1.83 eV-1.90 eV. Hall-effect measurements exhibited that all film have p-type conductivity with low hole concentration (~10 11 -10 12 cm -3 ) and high electrical resistivity (~10 4 -10 5 Ωcm).

A High Thermoelectric Performance ZT in p-Type LaSe2 Crystal

2021 ◽  
Vol 871 ◽  
pp. 203-207
Author(s):  
Jian Liu
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
High Power ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
High Power Factor ◽  
P Type

In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe2 crystal. The flat-and-dispersive type band structure of LaSe2 crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe2 semiconductor, combined with its high power factor, the LaSe2 crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe2 could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

Approaching the minimum lattice thermal conductivity of p-type SnTe thermoelectric materials by Sb and Mg alloying

2019 ◽  
Vol 64 (14) ◽  
pp. 1024-1030 ◽  
Author(s):  
Tiezheng Fu ◽  
Jiazhan Xin ◽  
Tiejun Zhu ◽  
Jiajun Shen ◽  
Teng Fang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Lattice Thermal Conductivity ◽  
P Type

The Influence of RuO2 Addition on the Thermoelectric Properties of BiSbTe Alloys

2012 ◽  
Vol 512-515 ◽  
pp. 1651-1654 ◽  
Author(s):  
Yu Kun Xiao ◽  
Zhi Xiang Li ◽  
Jun Jiang ◽  
Sheng Hui Yang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Combined Process ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Factor Α ◽  
P Type

P-type BiSbTe/RuO2 composite was fabricated using a combined process of melting and spark plasma sintering. The XRD patterns showed that RuO2 reacted with the matrix for the RuO2 content of 1.0 wt% and 4.0 wt% samples. The measured thermoelectric properties showed that the highest electrical conductivity was obtained for the sample with 2.0 wt% RuO2. The power factor (α2σ/κ) decreased with the increase of RuO2 below 450 K. The lattice thermal conductivity was lower than that of BiSbTe over the whole temperature range for BiSbTe/2.0 wt% RuO2.

Thermal transport properties of monolayer MoSe2 with defects

2020 ◽  
Vol 22 (10) ◽  
pp. 5832-5838 ◽  
Author(s):  
Jiang-Jiang Ma ◽  
Jing-Jing Zheng ◽  
Wei-Dong Li ◽  
Dong-Hong Wang ◽  
Bao-Tian Wang
Keyword(s):  
Thermal Conductivity ◽  
Transport Properties ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Thermal Transport Properties

The defects in monolayer MoSe2 have a significant effect on its lattice thermal conductivity.

Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

2015 ◽  
Vol 08 (02) ◽  
pp. 1550028 ◽  
Author(s):  
Qilong Guo ◽  
Sijun Luo
Keyword(s):  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Hole Concentration ◽  
Zn Deficiency ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Figure ◽  
Pristine Sample ◽  
Zn Content ◽  
P Type ◽  
Content Regulation

We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of ~ 0.8 at 700 K which is a ~ 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb -based material have been discussed.

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