The Effect of A Graded in Profile on the Figure of Merit of PbTe

1998 ◽  
Vol 545 ◽  
Author(s):  
Z. Dashevsky ◽  
S. Shusterman ◽  
A. Horowitz ◽  
M. P. Dariel
Keyword(s):  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Concentration Profile ◽  
External Source ◽  
Charge Carrier Concentration ◽  
Deep Impurity ◽  
Temperature Range ◽  
Fermi Level Pinning ◽  
Type Character ◽  
Set Up

AbstractThe present study was aimed at demonstrating the possibility of producing a graded charge carrier concentration in a PbTe crystal by taking advantage of the concentration profile that is set up by the diffusion of In from an external source. Doping by indium generates deep impurity levels lying close to the edge of the conduction band. The Fermi level pinning effect and the electron population of the In impurity levels, which reduces the minority carrier concentration at elevated temperature, significantly improve the thermoelectric behavior of the resulting material. The penetration profiles of In, originating from an external gaseous or liquid source, were determined using Seebeck coefficient measurements in p- and n-type PbTe crystals. In the p-type crystal, the Seebeck coefficient changed sign as the In concentration induced a change from p-type to n-type character. The thermovoltage of a PbTe crystal in which an In concentration profile, generated by In diffiusing from a gaseous source had been established, was determined in the 50 to 430 °C temperature range. The constant Seebeck coefficient that was observed over the whole temperature range provides the experimental support for the underlying premises of this study.

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

Unusually High Seebeck Coefficient Arisen from the Temperature-dependent Carrier Concentration in PbSe-AgSbSe2 Alloys

2021 ◽  
Author(s):  
Xuemei Wang ◽  
Gang Wu ◽  
Jianfeng Cai ◽  
Qiang Zhang ◽  
Junxuan Yang ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Wide Temperature Range ◽  
Induced Voltage ◽  
Temperature Dependent ◽  
Temperature Range ◽  
High Seebeck Coefficient

Seebeck coefficient describes the temperature gradient induced voltage in thermoelectrics. Usually, to obtain a high Seebeck coefficient within a wide temperature range is difficult, as it is limited by the...

Using the Seebeck coefficient to determine charge carrier concentration, mobility, and relaxation time in InAs nanowires

2014 ◽  
Vol 104 (1) ◽  
pp. 012113 ◽  
Author(s):  
Volker Schmidt ◽  
Philipp F. J. Mensch ◽  
Siegfried F. Karg ◽  
Bernd Gotsmann ◽  
Pratyush Das Kanungo ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Charge Carrier ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Charge Carrier Concentration ◽  
Inas Nanowires

CHARGE TRANSPORT IN GERMANIUM-SUBSTITUTED MAGNESIUM FERRITES

1994 ◽  
Vol 08 (16) ◽  
pp. 947-958 ◽  
Author(s):  
MD. ABDUL MALIK ◽  
V. D. REDDY ◽  
P. VENUGOPAL REDDY ◽  
D. R. SAGAR ◽  
PRANKISHAN
Keyword(s):  
Electrical Conductivity ◽  
Charge Carrier ◽  
Seebeck Coefficient ◽  
Charge Transport ◽  
Carrier Concentration ◽  
Carrier Mobility ◽  
Conduction Mechanism ◽  
Charge Carrier Mobility ◽  
Charge Carrier Concentration ◽  
Experimental Values

Electrical conductivity (σ) and thermopower measurements have been carried out on some Mg 1+x Ge x Fe 2−2x O 4 (0 < x < 0.4) ferrite samples over a temperature range 300–700 K. Using the experimental values of Seebeck coefficient at various temperatures, the values of charge carrier concentration have been determined. On the basis of the temperature variation of charge carrier mobility, the conduction mechanism in these ferrites has been discussed.

scholarly journals Understanding the Seebeck coefficient of LaNiO3 compound in the temperature range 300-620 K

2021 ◽  
Author(s):  
Arzena Khatun ◽  
Shamim Sk ◽  
Sudhir Kumar Pandey
Keyword(s):  
Seebeck Coefficient ◽  
Transition Metal Oxides ◽  
Structural Parameters ◽  
Combustion Process ◽  
Rhombohedral Structure ◽  
Temperature Dependent ◽  
Solution Combustion ◽  
Temperature Range ◽  
Refinement Method ◽  
Type Character

Abstract Transition metal oxides have been attracted much attention in thermoelectric community from the last few decades. In the present work, we have synthesized LaNiO3 by a simple solution combustion process. To analyze the crystal structure and structural parameters we have used Rietveld refinement method wherein FullProf software is employed. The room temperature x-ray diffraction indicates the rhombohedral structure with space group R 3 c (No. 167). The refined values of lattice parameters are a = b = c = 5.4071 Å. Temperature dependent Seebeck coefficient (S) of this compound has been investigated by using experimental and computational tools. The measurement of S is conducted in the temperature range 300-620 K. The measured values of S in the entire temperature range have negative sign that indicates n-type character of the compound. The value of S is found to be ∼ -8 µV/K at 300 K and at 620 K this value is ∼ -12 µV/K. The electronic structure calculation is carried out using DFT+U method due to having strong correlation in LaNiO3. The calculation predicts the metallic ground state of the compound. Temperature dependent S is calculated using BoltzTraP package and compared with experiment. The best matching between experimental and calculated values of S is observed when self-interaction correction is employed as double counting correction in spin-polarized DFT + U (= 1 eV) calculation. Based on the computational results maximum power factors are also calculated for p-type and n-type doping of this compound.

The influence of composition on polymorphism, structure and charge carrier concentration in TL-2201.

1994 ◽  
Vol 235-240 ◽  
pp. 539-540
Author(s):  
C. Ström ◽  
S.-G. Eriksson ◽  
J. Albertsson ◽  
N. Winzek
Keyword(s):  
Charge Carrier ◽  
Carrier Concentration ◽  
Charge Carrier Concentration

Ciliary Activity and Oxygen uptake in Branchiostoma Lanceolatum(Pallas)

1965 ◽  
Vol 43 (1) ◽  
pp. 1-12
Author(s):  
W. A. M. COURTNEY ◽  
R. C. NEWELL
Keyword(s):  
Oxygen Uptake ◽  
High Rate ◽  
Ciliary Activity ◽  
Oxygen Utilization ◽  
Nervous Control ◽  
Pharyngeal Wall ◽  
Temperature Range ◽  
Zero Rate ◽  
Branchiostoma Lanceolatum ◽  
Set Up

1. The rate of oxygen uptake by single specimens of Branchiostoma lanceolatum has been shown to vary considerably. Some animals in sealed vessels at 50° C. were able to utilize the oxygen linearly down to less than 20% of air saturation. Others ceased to absorb oxygen at high saturations while yet others displayed two different rates in a sequence starting initially with a high rate. 2. There are three possible rates of oxygen utilization, as well as a zero rate, for an animal at any temperature between 10 and 19° C. Animals in gravel exhibit only two rates at lower temperatures. 3. The slowest rate varies exponentially with temperature but the two faster rates show a rapid increase between 10 and 15° C. with little change outside this temperature range. 4. The effect of size and temperature on the increased oxygen uptake during the faster rates of respiration are discussed. It is suggested that ciliary activity of the pharynx could be associated with the extra oxygen utilization. 5. It has been found that there are three inhalant stream velocities, a fast, a slow and a zero rate with no intermediate rates. 6. Study of the isolated portions of the pharyngeal wall confirm that the fast inhalant current is set by the activity of all the cilia to give a feeding stream. The slow stream is set up by the lateral cilia, which continue to beat when the frontal cilia and most of the lateral cilia have been inhibited by lowered oxygen concentrations. 7. The lateral cilia have been shown to be under nervous control and to be inhibited by pressure on the pharyngeal bars. This mechanism depends on the presence of a connexion between the pharyngeal bars and the endostyle.

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