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1.
A thermopile sensor was processed on a glass substrate by electrodeposition of n-type bismuth telluride (Bi-Te) and p-type antimony telluride (Sb-Te) films. The n-type Bi-Te film electrodeposited at −50 mV in a 50 mM electrolyte with a Bi/(Bi + Te) mole ratio of 0.5 exhibited a Seebeck
coefficient of −51.6 μV/K and a power factor of 7.1 × 10−4 W/K2 · m. The p-type Sb-Te film electroplated at 20 mV in a 70 mM solution with an Sb/(Sb + Te) mole ratio of 0.9 exhibited a Seebeck coefficient
of 52.1 μV/K and a power factor of 1.7 × 10−4 W/K2 · m. A thermopile sensor composed of 196 pairs of the p-type Sb-Te and the n-type Bi-Te thin-film legs exhibited sensitivity of 7.3 mV/K. 相似文献
2.
Takashi Hamachiyo Maki Ashida Kazuhiro Hasezaki 《Journal of Electronic Materials》2009,38(7):1048-1051
A fine measurement system for measuring thermal conductivity was constructed. An accuracy of 1% was determined for the reference
quartz with a value of 1.411 W/m K. Bi0.5Sb1.5Te3 samples were prepared by mechanical alloying followed by hot-pressing. Grain sizes were varied in the range from 1 μm to 10 μm by controlling the sintering temperature in the temperature range from 623 K to 773 K. The thermal conductivity was 0.89 W/m K
for the sample sintered at 623 K, while a grain size of 1.75 μm was measured by optical microscopy and scanning electron microscopy. The thermal conductivity increased on the sample sintered
at 673 K because of grain growth and decreased on those sintered at the temperatures from 673 K to 773 K because the increase
of pore size caused to decrease thermal conductivity. The increase of thermal conductivity for the samples sintered at temperatures
above 773 K was affected by the increase of carrier concentration. 相似文献
3.
K. Rothe M. Stordeur F. Heyroth F. Syrowatka H. S. Leipner 《Journal of Electronic Materials》2010,39(9):1408-1412
A recent trend in thermoelectrics is miniaturization of generators or Peltier coolers using the broad spectrum of thin-film
and nanotechnologies. Power supplies for energy self-sufficient micro and sensor systems are a wide application field for
such generators. It is well known that thermal treatment of as-deposited p-type (Bi0.15Sb0.85)2Te3 films leads to enhancement of their power factors. Whereas up to now only the start (as-deposited) and the end (after annealing)
film stages were investigated, herein for the first time, the dynamical changes of sputter-deposited film properties have
been observed by real-time measurements. The electrical conductivity shows a distinct, irreversible increase during a thermal
cycle of heating to about 320°C followed by cooling to room temperature. The interpretation of the Seebeck and Hall coefficients
points to an enhancement in Hall mobility after annealing. In situ x-ray diffractometry shows the generation of an additional Te phase depending on temperature. This is also confirmed by energy-dispersive
x-ray microanalysis and the corresponding mapping by scanning electron microscopy. It is presumed that the Te enrichment in
a separate, locally well-defined phase is the reason for the improvement in the integral film transport properties. 相似文献
4.
Andrew Taylor Clay Mortensen Raimar Rostek Ngoc Nguyen David C. Johnson 《Journal of Electronic Materials》2010,39(9):1981-1986
This article demonstrates that carrier concentrations in bismuth telluride films can be controlled through annealing in controlled
vapor pressures of tellurium. For the bismuth telluride source with a small excess of tellurium, all the films reached a steady
state carrier concentration of 4 × 1019 carriers/cm3 with Seebeck coefficients of −170 μV K−1. For temperatures below 300°C and for film thicknesses of 0.4 μm or less, the rate-limiting step in reaching a steady state for the carrier concentration appeared to be the mass transport
of tellurium through the gas phase. At higher temperatures, with the resulting higher pressures of tellurium or for thicker
films, it was expected that mass transport through the solid would become rate limiting. The mobility also changed with annealing,
but at a rate different from that of the carrier concentration, perhaps as a consequence of the non-equilibrium concentration
of defects trapped in the films studied by the low temperature synthesis approach. 相似文献
5.
n-Type nanoporous Bi2Te3-based thermoelectric materials with different porosity ratios have been prepared by spark plasma sintering (SPS). The microstructure
and phase morphology have been analyzed by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM),
and the thermoelectric properties of the SPS samples have been measured. Experimental results show that the nanoporous structures
lying in the sheet layers and among the plate grains of the Bi2Te3 bulk material can lead to an increase in the Seebeck coefficient and a decrease in the thermal conductivity, thus leading
to an enhanced figure of merit. 相似文献
6.
S. Yamanaka M. Ishimaru A. Charoenphakdee H. Matsumoto K. Kurosaki 《Journal of Electronic Materials》2009,38(7):1392-1396
The key properties for the design of high-efficiency thermoelectric materials are a low thermal conductivity and a large Seebeck
coefficient with moderate electrical conductivity. Recent developments in nanotechnology and nanoscience are leading to breakthroughs
in the field of thermoelectrics. The goal is to create a situation where phonon pathways are disrupted due to nanostructures
in “bulk” materials. Here we introduce promising materials: (Ga,In)2Te3 with unexpectedly low thermal conductivity, in which certain kinds of superlattice structures naturally form. Two-dimensional
vacancy planes with approximately 3.5-nm intervals exist in Ga2Te3, scattering phonons efficiently and leading to a very low thermal conductivity. 相似文献
7.
Jan D. König M. Winkler S. Buller W. Bensch U. Schürmann L. Kienle H. Böttner 《Journal of Electronic Materials》2011,40(5):1266-1270
In this work, Bi2Te3-Sb2Te3 superlattices were prepared by the nanoalloying approach. Very thin layers of Bi, Sb, and Te were deposited on cold substrates,
rebuilding the crystal structure of V2VI3 compounds. Nanoalloyed super- lattices consisting of alternating Bi2Te3 and Sb2Te3 layers were grown with a thickness of 9 nm for the individual layers. The as-grown layers were annealed under different conditions
to optimize the thermoelectric parameters. The obtained layers were investigated in their as-grown and annealed states using
x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) spectroscopy, transmission electron
microscopy (TEM), and electrical measurements. A lower limit of the elemental layer thickness was found to have c-orientation. Pure nanoalloyed Sb2Te3 layers were p-type as expected; however, it was impossible to synthesize p-type Bi2Te3 layers. Hence the Bi2Te3-Sb2Te3 superlattices consisting of alternating n- and p-type layers showed poor thermoelectric properties. 相似文献
8.
The magnetic susceptibility of Czochralski-grown single crystals of Bi2Te3-Sb2Te3 alloys containing 0, 10, 25, 40, 50, 60, 65, 70, 80, 90, 99.5, or 100 mol % Sb2Te3 has been investigated. The magnetic susceptibility of these crystals was determined at the temperature T = 291 K and the magnetic field H oriented parallel (χ‖) and perpendicularly (χ⊥) to the trigonal crystallographic axis C 3. A complicated concentration dependence of the anisotropy of magnetic susceptibility χ‖/χ⊥ has been revealed. The crystals with the free carrier concentration p ≈ 5 × 1019 cm?3 do not exhibit anisotropy of magnetic susceptibility. The transition to the isotropic magnetic state occurs for the compositions characterized by a significantly increased (from 200 to 300 meV) optical bandgap. 相似文献
9.
HyunWoo You Sung-Hwan Bae Jongman Kim Jin-Sang Kim Chan Park 《Journal of Electronic Materials》2011,40(5):635-640
Nanocrystalline Bi2Te3 films were deposited on (100) GaAs substrates using a modified metalorganic chemical vapor deposition (MOCVD) system, and the effect of growth parameters on the structural properties were investigated. The modified MOCVD system employed a mixing room for the formation of nanoparticles of Bi2Te3 by gas-phase reaction and a graphite susceptor for growth of nanoparticles on the substrate. The grown films contained many crystallites of nanosize, and large crystallites consisted of small particles a few tens of nanometer in size. This nanostructured film approach can be an economical way of producing high-performance thermoelectric films with nanostructure compared with other top-down methods. 相似文献
10.
Chia-Jyi Liu Gao-Jhih Liu Chun-Wei Tsao Yo-Jhih Huang 《Journal of Electronic Materials》2009,38(7):1499-1503
We report on the successful hydrothermal synthesis of Bi0.5Sb1.5Te3, using water as the solvent. The products of the hydrothermally prepared Bi0.5 Sb1.5Te3 were hexagonal platelets with edges of 200–1500 nm and thicknesses of 30–50 nm. Both the Seebeck coefficient and electrical
conductivity of the hydrothermally prepared Bi0.5Sb1.5Te3 were larger than those of the solvothermally prepared counterpart. Hall measurements of Bi0.5Sb1.5Te3 at room temperature indicated that the charge carrier was p-type, with a carrier concentration of 9.47 × 1018 cm−3 and 1.42 × 1019 cm−3 for the hydrothermally prepared Bi0.5Sb1.5Te3 and solvothermally prepared sample, respectively. The thermoelectric power factor at 290 K was 10.4 μW/cm K2 and 2.9 μW/cm K2 for the hydrothermally prepared Bi0.5Sb1.5Te3 and solvothermally prepared sample, respectively. 相似文献
11.
Tae-Sung Oh 《Journal of Electronic Materials》2009,38(7):1041-1047
The p-type (Bi,Sb)2Te3/(Pb,Sn)Te functional gradient materials (FGMs) were fabricated by hot-pressing mechanically alloyed (Bi0.2Sb0.8)2Te3 and 0.5 at.% Na2Te-doped (Pb0.7Sn0.3)Te powders together at 500°C for 1 h in vacuum. Segment ratios of (Bi,Sb)2Te3 to (Pb,Sn)Te were varied as 3:1, 1.3:1, and 1:1.6. A reaction layer of about 350-μm thickness was formed at the (Bi,Sb)2Te3/(Pb,Sn)Te FGM interface. Under temperature differences larger than 340°C applied across a specimen, superior figures of merit
were predicted for the (Bi,Sb)2Te3/(Pb,Sn)Te FGMs to those of (Bi0.2Sb0.8)2Te3 and (Pb0.7Sn0.3)Te. With a temperature difference of 320°C applied across a specimen, the (Bi,Sb)2Te3/(Pb,Sn)Te FGMs with segment ratios of 3:1 and 1.3:1 exhibited the maximum output powers of 72.1 mW and 72.6 mW, respectively,
larger than the 63.9 mW of (Bi0.2Sb0.8)2Te3 and the 26 mW of 0.5 at.% Na2Te-doped (Pb0.7Sn0.3)Te. 相似文献
12.
S. Stefanoski L. N. Reshetova A. V. Shevelkov G. S. Nolas 《Journal of Electronic Materials》2009,38(7):985-989
We report on temperature-dependent thermal conductivity, resistivity, and Seebeck coefficient of two polycrystalline Br-containing
Sn-clathrate compounds with the type I crystal structure. Interstitial Br atoms reside inside the polyhedral cavities formed
by the framework, resulting in hole conduction. The framework bonding directly influences the transport properties of these
two compositions. The transport properties of these two clathrates are compared with those of other Sn-clathrates. We also
discuss our results in terms of the potential for thermoelectric applications. 相似文献
13.
D. G. Ebling A. Jacquot H. Böttner L. Kirste J. Schmidt M. Aguirre 《Journal of Electronic Materials》2009,38(7):1450-1455
Thermoelectric compounds based on doped bismuth telluride and its alloys have recently attracted increasing interest. Due
to their structural features they show increased values of the thermoelectric figure of merit (ZT). A promising approach to improve the thermoelectric properties is to manufacture nanocomposite materials exhibiting lower
thermal conductivities and higher ZT. The ZT value of compounds can be shifted reasonably to higher values (>1) by alloying with IV-Te materials and adequate preparation
methods to form stable nanocomposites. The influence of PbTe and Sn on the thermoelectric properties is studied as a function
of concentration and preparation methods. Melt spinning and spark plasma sintering were applied to form nanocomposite materials
that were mechanically and thermodynamically stable for applications in thermoelectric devices. The structural properties
are discussed based on analysis by transmission electron microscopy and x-ray diffraction. 相似文献
14.
L. I. Anatychuk L. N. Vikhor L. T. Strutynska I. S. Termena 《Journal of Electronic Materials》2011,40(5):957-961
Previously, the Institute of Thermoelectricity has created Bi2Te3-based modules with an efficiency of ~7% in the temperature range of 30°C to 300°C, with legs that employed homogeneous thermoelectric
materials. Herein, we present the results of development of such modules with legs made of inhomogeneous materials. Based
on the theory of optimal control and object-oriented computer technology, programs to determine the requirements for material
properties in the inhomogeneous legs were created. It was established that introduction of inhomogeneity in the form of continuous
and step changes in three-segment n- and p-type legs yields almost identical efficiency increases of about 15%. Use of two segments reduces this value of 10% to 12%.
Modules with two-segment legs encapsulated in thin-walled metal cases filled with inert gas have been built, yielding improved
efficiency of 7.8% to 8%. 相似文献
15.
Biprodas Dutta Jugdersuren Battogtokh David Mckewon Igor Vidensky Neilanjan Dutta Ian L. Pegg 《Journal of Electronic Materials》2007,36(7):746-752
NaCo2O4 has one of the highest figures of merit among all ceramic thermoelectric materials. Because of its large thermopower and
low resistivity, the ceramic oxide NaCo2O4 is a promising candidate for potential thermoelectric applications. NaCo2O4 is, moreover, a ceramic compound with high decomposition temperature and chemical stability in air and it does not contain
any toxic elements. Like all 3-d transition ions, Co ions have multiple spin and oxidation states. In this investigation,
thermopower and electrical conductivity of NaCo2O4 as a function of substitution of Co by Fe ions were measured. Fe substitution for Co causes resistivity to increase, whereas
the Seebeck coefficient remained nearly invariant, especially above 330 K.
An erratum to this article can be found at 相似文献
16.
In this work, nano-structured Bi2Te3 and PbTe thermoelectric materials were synthesized separately via solvothermal, hydrothermal and low-temperature aqueous
chemical routes. X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), transmission electron microscopy
(TEM), and energy dispersive spectroscopy (EDS) were used to analyze the powder products. Results showed that the as-prepared
Bi2Te3 samples were all single-phased and consisted of irregular spherical granules with diameters of ∼30 nm whereas the PbTe samples
were mainly composed of well-crystallized cubic crystals with average size of approximately 100 nm. Some nanotubes and nanorods
were found in Bi2Te3 and PbTe samples, respectively; these were identified as Bi2Te3 nanotubes and PbTe nanorods by EDS analysis. Possible reaction mechanisms for these syntheses are discussed in detail herein. 相似文献
17.
B. N. Pantha R. Dahal J. Li J. Y. Lin H. X. Jiang G. Pomrenke 《Journal of Electronic Materials》2009,38(7):1132-1135
We report on the experimental investigation of the potential of InGaN alloys as thermoelectric (TE) materials. We have grown
undoped and Si-doped In0.3Ga0.7N alloys by metalorganic chemical vapor deposition and measured the Seebeck coefficient and electrical conductivity of the
grown films with the aim of maximizing the power factor (P). It was found that P decreases as electron concentration (n) increases. The maximum value for P was found to be 7.3 × 10−4 W/m K2 at 750 K in an undoped sample with corresponding values of Seebeck coefficient and electrical conductivity of 280 μV/K and 93␣(Ω cm)−1, respectively. Further enhancement in P is expected by improving the InGaN material quality and conductivity control by reducing background electron concentration. 相似文献
18.
A. A. Kudryashov V. G. Kytin R. A. Lunin V. A. Kulbachinskii A. Banerjee 《Semiconductors》2016,50(7):869-875
The Shubnikov–de Haas effect and the Hall effect in n-Bi2–xTlxSe3 (x = 0, 0.01, 0.02, 0.04) and p-Sb2–xTlxTe3 (x = 0, 0.005, 0.015, 0.05) single crystals are studied. The carrier mobilities and their changes upon Tl doping are calculated by the Fourier spectra of oscillations. It is found shown that Tl doping decreases the electron concentration in n-Bi2–xTlxSe3 and increases the electron mobility. In p-Sb2–xTlxTe3, both the hole concentration and mobility decrease upon Tl doping. The change in the crystal defect concentration, which leads to these effects, is discussed. 相似文献
19.
H. Kitagawa A. Kurata H. Araki S. Morito E. Tanabe 《Journal of Electronic Materials》2010,39(9):1692-1695
The effects of deformation temperature on texture and thermoelectric properties of p-type Bi0.5Sb1.5Te3 sintered materials were investigated. The sintered materials were prepared by mechanical alloying and hot-press sintering.
The hot-press deformation was performed at 723 K and 823 K by applying mechanical pressure in a graphite die. Then, the materials
were extruded in the direction opposite to the direction of applied pressure. X-ray diffraction and electron backscattered
diffraction patterns showed that the hexagonal c-plane tended to align along the extruded direction when the samples were deformed at high temperatures. The thermoelectric
power factor was increased by high-temperature hot-press deformation because of the low electrical resistivity that originated
from the c-plane orientation. 相似文献
20.
Ju-Hyuk Yim Kyooho Jung Hyo-Jung Kim Hyung-Ho Park Chan Park Jin-Sang Kim 《Journal of Electronic Materials》2011,40(5):1010-1014
The solidification of alloys in the Bi2Te3-PbTe pseudobinary system at off- and near-eutectic compositions was investigated for their microstructure and thermoelectric
properties. Dendritic and lamellar structures were clearly observed due to the phase separation and the existence of a metastable
ternary phase. In this system, three phases with different compositions were observed: binary Bi2Te3, PbTe, and metastable PbBi2Te4. The Seebeck coefficient, electrical resistivity, and thermal conductivity of ternary alloys as well as binary compounds
were measured. The phonon thermal conductivities of Pb-Bi-Te alloys were lower than those in binary PbTe and Bi2Te3, which could have resulted from the increased interfacial area between phases due to the existence of the metastable ternary
phase and the resultant phase separation. 相似文献