Evaluation of Thermoelectric Properties of Cu3.21Bi4.79S9 Bismuth Chalcogenide

2016 ◽  
Vol 701 ◽  
pp. 220-224
Author(s):  
Milan Chandra Barma ◽  
Bui Duc Long ◽  
Mohd Faizul Mohd Sabri ◽  
Ramesh Singh ◽  
Suhana Mohd Said ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Mechanical Alloying ◽  
Seebeck Coefficient ◽  
Single Phase ◽  
Hot Isostatic Pressing ◽  
Milled Powder ◽  
Measuring System ◽  
Secondary Phases ◽  
Type Conversion ◽  
Increasing Temperature

Cu3.21Bi4.79S9 was synthesized from Cu, Bi and S element powders using mechanical alloying method. The formation of Cu3.21Bi4.79S9 was identified using XRD and the changes of morphologies of the mixtures of Cu, Bi, and S powders during milling were observed using table top SEM. The milled powders were sintered using Hot-isostatic pressing at 230°C with a pressure of 50 MPa. Electrical resistivity and Seebeck coefficient of sintered samples were measured using ZEM-3 (Electrical resistivity and Seebeck Coefficient measuring System). Cu3.21Bi4.79S9 and some secondary phases were found in the 5h milled powder but single phase Cu3.21Bi4.79S9 was only obtained after milling for 15 h. A minimum electrical resistivity of sintered Cu3.21Bi4.79S9 sample was found to be 0.66 Ω.m at 170°C. We observed that a n- to p-type conversion at temperature of around 75 °C. However, a maximum n-type Seebeck coefficient of Cu3.21Bi4.79S9 was of -214 μV/K at 45 °C. The Seebeck coefficient decreases with increasing temperature and it reaches zero value at around 75 °C and then p-type Seebeck coefficient increases with increasing the temperature. The maximum p-type Seebeck coefficient was observed of 202 μV/K at 170°C.

Microstructure and Thermoelectric Properties of Na0.5CoO2

2013 ◽  
Vol 802 ◽  
pp. 218-222 ◽  
Author(s):  
Wanatchaporn Namhongsa ◽  
Tosawat Seetawan ◽  
Pennapa Muthitamongkol ◽  
Chanchana Thanachayanont
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
Powder Size ◽  
Sodium Ions ◽  
Small Particle Size ◽  
Orthorhombic Structure ◽  
Sodium Cobalt Oxide ◽  
Sintering Method

The polycrystalline of sodium cobalt oxide (Na0.5CoO2) was synthesized by solid state reaction method and sintering method. The microstructure was composed of powder size and crystal structure. The Seebeck coefficient and electrical resistivity are measured. We found that the concentration of sodium ions sandwiched between two neighboring CoO2layers played a crucial role in transport properties. The results showed small particle size, single phase and orthorhombic structure. The Seebeck coefficient of Na0.5CoO2increased as the temperature increased. The electrical resistivity was decreased as temperature decreased from the range 300-500 K.

Cu-induced Seebeck peak in HMS/Si film

2014 ◽  
Vol 28 (22) ◽  
pp. 1450176 ◽  
Author(s):  
Q. R. Hou ◽  
B. F. Gu ◽  
Y. B. Chen
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Bulk Material ◽  
Energy Levels ◽  
Thermoelectric Power Factor ◽  
Silicide Layer ◽  
Manganese Silicide ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
Peak Value

It is well known that aluminum ( Al ), boron ( B ) and copper ( Cu ) are acceptor impurities with shallow- and deep-energy levels in silicon ( Si ), respectively. Thus, Al and B impurities with shallow-energy levels in Si are essentially completely ionized at room temperature while Cu impurities with deep-energy levels in Si at higher temperature. In this paper, Al , B and Cu co-doped Si layer is used as a barrier layer while the higher manganese silicide layer (HMS) as a well layer. The Seebeck coefficient (S) of Al and Cu modulation doped film, HMS/ Si :( Al + Cu ), increases sharply above 583 K, reaches a peak value of 0.300 mV/K at 683 K, and then decreases with further increasing temperature. Concomitance with the great increase in Seebeck coefficient, however, the electrical resistivity (R) is still smaller than that of only Al modulation doped film, HMS/ Si : Al . The Cu -induced Seebeck peak, S max = 0.303 mV/K at 733 K, and reduction in electrical resistivity are also observed in ( B + Al + Cu ) modulation doped film, Si :( B + Al + Cu )/HMS/ Si :( B + Al + Cu ), where B is used to reduce the electrical resistivity further. As a result, the thermoelectric power factor (PF = S2/R) is greatly enhanced and can reach 3.140 × 10-3 W/m-K2 at 733 K, which is larger than that of HMS bulk material.

Lanthanide Based Ternary Intermetallics as Advanced Thermoelectric Materials

2006 ◽  
Vol 980 ◽  
Author(s):  
Ken Kurosaki ◽  
Takeyuki Sekimoto ◽  
Kenta Kawano ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Single Phase ◽  
Type Structure ◽  
Large Power

AbstractPolycrystalline ingots of the lanthanide based ternary intermetallics: LaNiSb, GdNiSb, ErNiSb and ErPdSb were prepared and characterized. The thermoelectric properties of ErNiSb and ErPdSb were measured at high temperatures. We succeeded in preparing the single phase ingots of ErNiSb and ErPdSb, while the ingots of LaNiSb and GdNiSb contain appreciable quantities of the impurity phases. ErNiSb and ErPdSb crystallize the MgAgAs-type structure (half-Heusler structure). ErNiSb and ErPdSb indicate positive values of the Seebeck coefficient. The values at room temperature are 36 and 240 micro VK-1 for ErNiSb and ErPdSb, respectively. The electrical resistivity of ErNiSb and ErPdSb decreases with temperature, indicating semiconductor-like behavior. ErPdSb exhibits a relatively large power factor 1.5x10-3 Wm-1K-2 at around 700 K, which is approximately two times larger than that of ErNiSb.

Thermoelectric Properties of Zn4-xSb3 with x=0~0.5

2007 ◽  
Vol 124-126 ◽  
pp. 1019-1022 ◽  
Author(s):  
K.W. Jang ◽  
Il Ho Kim ◽  
Jung Il Lee ◽  
Good Sun Choi
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Hall Mobility ◽  
Room Temperature ◽  
Vacuum Melting ◽  
Increasing Temperature

Non-stoichiometric Zn4-xSb3 compounds with x=0~0.5 were prepared by vacuum melting at 1173K and annealing solidified ingots at 623K. Electrical resistivity and Seebeck coefficient at 450K increased from 1.8cm and 145K-1 for Zn4Sb3(x=0) to 56.2cm 350K-1 for Zn3.5Sb3(x=0.5) due to the decrease of the carrier concentration. Hall mobility and carrier concentration was 31.5cm2V-1s-1 and 1.32X1020cm-3 for Zn4Sb3 and 70cm2V-1s-1 and 2.80X1018cm-3 for Zn3.5Sb3. Electrical resistivity of Zn4-xSb3 with x=0~0.2 showed linearly increasing temperature dependence, whereas those of Zn4-xSb3 with x=0.3~0.5 above 450 K tended to decrease. Thermal conductivity of Zn4Sb3 was 8.5mWcm-1K-1 at room temperature and that of Zn4-xSb3 with x≥0.3 was around 11mWcm-1K-1. Maximum ZT of Zn4Sb3 was obtained around 1.3 at 600K. Zn4Sb3 with x=0.3~0.5 showed very small value of ZT=0.2~0.3.

INFLUENCE OF SILICON ADDITION ON SEEBECK COEFFICIENT OF MnSi1.7 FILMS

2011 ◽  
Vol 25 (18) ◽  
pp. 2393-2402 ◽  
Author(s):  
Q. R. HOU ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Film Thickness ◽  
Seebeck Coefficient ◽  
Room Temperature ◽  
Electron Beam Evaporation ◽  
Aluminum Layer ◽  
Seebeck Coefficients ◽  
Thin Aluminum ◽  
Increasing Temperature ◽  
P Type

MnSi 1.7 films with different thicknesses (16–242 nm) are prepared by magnetron sputtering and electron beam evaporation. When the MnSi 1.7 film thickness is about 40 nm or above, MnSi 1.7 films are p-type in the whole temperature range (300–700 K) in agreement with reports in literature. By co-sputtering of MnSi 1.85 and silicon targets or deposition of Si / Mn multi-layers with a larger thickness ratio, silicon is added to the films and the Seebeck coefficients transform from positive to negative with increasing temperature. The Seebeck coefficients at room temperature and 633 K are +0.098 mV/K and -0.358 mV/K, respectively. By reducing the MnSi 1.7 film thickness to 27 nm, the transition of Seebeck coefficient from positive to negative is also observed although silicon is not added intentionally. When an ultra-thin aluminum layer is deposited between MnSi x(x < 1.7) and Si layers to enhance silicon diffusion, the p- to n-type transition temperature decreases about 100 K. The silicon-added MnSi 1.7 films usually have higher electrical resistivity.

Thermoelectric Properties of Bi-substituted Ca3Co4O9 Single Crystal

2003 ◽  
Vol 793 ◽  
Author(s):  
M. Mikami ◽  
K. Chong ◽  
R. Funahashi
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Temperature Region ◽  
Solution Method ◽  
Crystallographic Structure ◽  
Thermoelectric Power Factor ◽  
Cationic Composition ◽  
X Ray ◽  
Increasing Temperature

ABSTRACTWe have grown single crystals of Bi-substituted Ca3Co4O9 by a solution method. The cationic ratio (Ca, Bi)/Co of the grown crystals measured by an energy dispersive X-ray spectrometer tended to exceed that of the starting ratio (Ca, Bi)/Co=3/4. For instance, the average cationic composition of the grown crystals was Ca:Bi:Co=3.3:0.3:4, while that of the starting material was Ca:Bi:Co=2.7:0.3:4. So, the crystallographic structure of the obtained crystals may correspond to the Ca2Co2O5 phase rather than the Ca3Co4O9 phase. Thermoelectric properties in the direction of ab-axis were measured at various temperatures. Seebeck coefficient (S) of Ca3.3Bi0.3Co4O9+δ is positive and increases with increasing temperature from 130 to 200 μV/K in a temperature region of 300–973 K. The electrical resistivity (ρ) of the sample is about 1.5 mΩcm at whole temperature region of 300–973 K. This value is lower than that of non-substituted Ca3Co4O9. The thermoelectric power factor (S2/ρ) is improved by the Bi-substitution, resulting from the reduction of resistivity.

Thermoelectric Properties of PbTe

2013 ◽  
Vol 802 ◽  
pp. 223-226 ◽  
Author(s):  
Sunti Phewphong ◽  
Tosawat Seetawan
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Room Temperature ◽  
Single Phase ◽  
Argon Atmosphere ◽  
Steady State Method ◽  
State Method ◽  
Cubic Structure ◽  
Annealing Method

The PbTe has been prepared by pressing and annealing method in argon atmosphere. The PbTe sample was obtained single phase and cubic structure. The Seebeck coefficient, the electrical resistivity, thermal conductivity measured by steady state method and evaluated dimensionless figure merit at room temperature. The values of Seebeck coefficient, the electrical resistivity, thermal conductivity and dimensionless figure merit are about -260 µV/K, 3 mΩcm, 0.5 W/m K and ~ 0.35 respectively at 420 K.

Phase Transformation and Thermoelectric Properties of Sn-Filled/Fe-Doped CoSb3 Skutterudites

2011 ◽  
Vol 312-315 ◽  
pp. 223-228
Author(s):  
Il Ho Kim
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Phonon Scattering ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Scattering Centers ◽  
Δ Phase ◽  
Increasing Temperature ◽  
P Type

Sn-filled and Fe-doped CoSb3 skutterudites were synthesized by encapsulated induction melting. A single δ-phase was obtained by subsequent annealing, as confirmed by X-ray diffraction. The as-solidified ingot consisted of mixed phases of -CoSb, -CoSb2, δ-CoSb3 and elemental Sb. The phases could be transformed by annealing, and the phases of the as-solidified ingot annealed at 773 K for 24 h transformed to δ-CoSb3. The temperature dependence of the Seebeck coefficient, electrical resistivity and thermal conductivity were examined from 300 K to 700 K. The positive Seebeck coefficient confirmed p-type conduction. The electrical resistivity increased with increasing temperature, which showed that the SnzCo3FeSb12 skutterudite is highly degenerate. The thermal conductivity was reduced by Sn-filling because the filler atoms acted as phonon scattering centers in the skutterudite lattice. The thermoelectric figure of merit was enhanced by Sn filling and its optimum composition was considered to be Sn0.3Co3FeSb12.

Doping Characteristics of Silver in Mg2Si1-xGex Prepared by Plasma Activated Sintering

2007 ◽  
Vol 1044 ◽  
Author(s):  
Takashi Nemoto ◽  
Junichi Sato ◽  
Tsutomu Iida ◽  
Masayasu Akasaka ◽  
Atsunobu Matsumoto ◽  
...  
Keyword(s):  
Seebeck Coefficient ◽  
Room Temperature ◽  
Doping Concentration ◽  
Source Material ◽  
Type Conversion ◽  
Activated Sintering ◽  
Increasing Temperature ◽  
P Type ◽  
Plasma Activated Sintering ◽  
Residual Impurities

AbstractSilver (Ag) doped Mg2Si1-xGex (x=0.1 to 0.4) samples were fabricated using a plasma activated sintering (PAS) method. The doping concentration of Ag was varied from 1 to 5 at.%. Undoped Mg2Si1-xGex exhibits n-type conductivity due to residual impurities in the Mg source material used and unintentionally process-induced impurities. The observed unstable behavior of the Seebeck coefficient of Ag-doped p-type Mg2Si1-xGex (x ≤ 0.3) in the region of 550 to 650 K, exhibiting a considerable drop in the value and occasional conduction type conversion, was correlated with the specific contaminants. For x∼0.4, the observed Seebeck coefficient varied from 0.2 mV/K at 823 K to 0.4 mV/K at room temperature, with no remarkable drop in the value with increasing temperature. An estimated ZT value of 5 at.% Ag doped Mg2Si0.6Ge0.4 was 0.18 at 844 K. It was found that both specific residual impurities and process-induced impurities affected the characteristics of the Seebeck coefficient of Mg2Si1-xGex.

Bi2Te3 and Bi2Te3/Nano-SiC Prepared by Mechanical Alloying and Spark Plasma Sintering

2007 ◽  
Vol 280-283 ◽  
pp. 397-400 ◽  
Author(s):  
Jing Liu ◽  
Jing Feng Li
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Mechanical Alloying ◽  
Seebeck Coefficient ◽  
Spark Plasma Sintering ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Mechanically Alloyed ◽  
Plasma Sintering ◽  
Spark Plasma

Bi2Te3-based alloys are currently best-known, technological thermoelectric materials near room temperature. In this paper, Bi2Te3 and nano-SiC dispersed Bi2Te3 were prepared by mechanical alloying followed by spark plasma sintering (SPS). Raw powders of Bi, Te and SiC were mixed and mechanically alloyed in an argon atmosphere using a planetary ball mill. The SPS temperature was 623K, and the holding time was 5 minutes. The samples were characterized by X-ray Diffraction (XRD) and Scanning electron Microscope (SEM). The thermoelectric properties: i.e. Seebeck coefficient, electrical resistivity and thermal conductivity were measured at temperatures from room temperature to 573K, followed by the evaluation of figure of merit. The results revealed that the SiC dispersion in the Bi2Te3 matrix increased Seebeck coefficient. Although the electrical resistivity was increased somewhat, the thermal conductivity was reduced by the SiC dispersion, indicating that promising thermoelectric materials with enhanced mechanical properties may be obtained in the nano-SiC dispersed Bi2Te3 composites with optimal compositions.

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