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1.
The best films for thermoelectric applications near room temperature are based on the compounds Bi2Te3, Sb2Te3, and Bi2Se3, which as single crystals have distinct anisotropy in their electrical conductivity σ regarding the trigonal c-axis, whereas the Seebeck coefficient S is nearly isotropic. For p- and n-type alloys, P
⊥c > P
||c, and the power factors P
⊥c of single crystals are always higher compared with polycrystalline films, where the power factor is defined as P = S
2
σ, ⊥c and ||c are the direction perpendicular and parallel to the c-axis, respectively. For the first time in sputter-deposited
p-type (Bi0.15Sb0.85)2Te3 and n-type Bi2(Te0.9Se0.1)3 thin films, the anisotropy of the electrical conductivity has been measured directly as it depends on the angle φ between the electrical current and the preferential orientation of the polycrystals (texture) using a standard four-probe
method. The graphs of σ(φ) show the expected behavior, which can be described by a weighted mixture of σ
⊥c and σ
||c contributions. Because (σ
⊥c/σ
||c)
p
< (σ
⊥c/σ
||c)
n
, the n-type films have stronger anisotropy than the p-type films. For this reason, the angular weighted contributions of P
||c lead to a larger drop in the power factor of polycrystalline n-type films compared with p-type films. 相似文献
2.
S. Y. Wang W. J. Xie H. Li X. F. Tang Q. J. Zhang 《Journal of Electronic Materials》2011,40(5):1150-1157
A series of Bi2(Se0.4Te0.6)3 compounds were synthesized by a rapid route of melt spinning (MS) combined with a subsequent spark plasma sintering (SPS)
process. Measurements of the Seebeck coefficient, electrical conductivity, and thermal conductivity were performed over the
temperature range from 300 K to 520 K. The measurement results showed that the cooling rate of melt spinning had a significant
impact on the transport properties of electrons and phonons, effectively enhancing the thermoelectric properties of the compounds.
The maximum ZT value reached 0.93 at 460 K for the sample prepared with the highest cooling rate, and infrared spectrum measurement results
showed that the compound with lower tellurium content, Bi2(Se0.4Te0.6)3, possesses a larger optical forbidden gap (E
g) compared with the traditional n-type zone-melted material with formula Bi2(Se0.07Te0.93)3. Our work provides a new approach to develop low-tellurium-bearing Bi2Te3-based compounds with good thermoelectric performance. 相似文献
3.
Shufen Fan Junnan Zhao Qingyu Yan Jan Ma Huey Hoon Hng 《Journal of Electronic Materials》2011,40(5):1018-1023
n-Type Bi2Te3 nanocomposites with enhanced figure of merit, ZT, were fabricated by a simple, high-throughput method of mixing nanostructured Bi2Te3 particles obtained through melt spinning with micron-sized particles. Moderately high power factors were retained, while
the thermal conductivity of the nanocomposites was found to decrease with increasing weight percent of nanoinclusions. The
peak ZT values for all the nanocomposites were above 1.1, and the maximum shifted to higher temperature with increasing amount of
nanoinclusions. A maximum ZT of 1.18 at 42°C was obtained for the 10 wt.% nanocomposite, which is a 43% increase over the bulk sample at the same temperature.
This is the highest ZT reported for n-type Bi2Te3 binary material, and higher ZT values are expected if state-of-the-art Bi2Te3−x
Se
x
materials are used. 相似文献
4.
Jae-Hong Lim Mi Yeong Park Dong Chan Lim Bongyoung Yoo Jung-Ho Lee Nosang V. Myung Kyu Hwan Lee 《Journal of Electronic Materials》2011,40(5):1321-1325
Thermoelectric Sb
x
Te
y
films were potentiostatically electrodeposited in aqueous nitric acid electrolyte solutions containing different concentrations
of TeO2. Stoichiometric Sb
x
Te
y
films were obtained by applying a voltage of −0.15 V versus saturated calomel electrode (SCE) using a solution consisting
of 2.4 mM TeO2, 0.8 mM Sb2O3, 33 mM tartaric acid, and 1 M HNO3. The nearly stoichiometric Sb2Te3 films had a rhombohedral structure, R[`3]m R\bar{3}m , with a preferred orientation along the (015) direction. The films had hole concentration of 5.8 × 1018/cm3 and exhibited mobility of 54.8 cm2/Vs. A more negative potential resulted in higher Sb content in the deposited Sb
x
Te
y
films. Furthermore, it was observed that the hole concentration and mobility decreased with increasingly negative deposition
potential, and eventually showed insulating properties, possibly due to increased defect formation. The absolute value of
the Seebeck coefficient of the as-deposited Sb2Te3 thin film at room temperature was 118 μV/K. 相似文献
5.
J. J. Shen Z. Z. Yin S. H. Yang C. Yu T. J. Zhu X. B. Zhao 《Journal of Electronic Materials》2011,40(5):1095-1099
The thermoelectric (TE) performance of Bi0.5Sb1.5Te3 polycrystalline alloys has been improved by a simple hot-forging process. No obvious texture was observed in the x-ray diffraction
(XRD) patterns of the hot-forged samples. Transport property measurements indicated that the hot-forged samples possessed
extremely low thermal conductivities. A maximum ZT value of ∼1.1 at room temperature was obtained for the sample forged under 30 MPa pressure, being almost 50% more than that
of the initial unforged alloy. High-resolution transmission electron microscopy (HRTEM) observations suggested that the high
density of lattice defects of the hot-forged samples could be responsible for the extremely low thermal conductivities. 相似文献
6.
Atmospheric water may condense on the surface of Bi2Te3-based compounds constituting the Peltier module, depending on the operating environment used. In the stage of disposal, Bi2Te3-based compounds may come into contact with water in waste disposal sites. There are very few publications about the influence of condensed water on Peltier modules. Bi2Te3-Sb2Te3 or Bi2Te3-Bi2Se3 pseudo binary system compounds are used as p-type material or n-type material, respectively. The lattice distortion will be induced in the crystal of Bi2Te3-based compounds by element substitution due to the reduction in their thermal conductivity. However, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds remains unclear. In this study, the influence of element substitution on the corrosion behavior of Bi2Te3-based compounds with practical compositions has been investigated. Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 was prepared by the vertical Bridgman method. The electrochemical properties at room temperature were evaluated by cyclic voltammetry in a standard three-electrode cell. The working electrolyte was a naturally aerated 0.6 or 3.0 mass% NaCl solution. From the tendency for corrosion potential for all the samples, the corrosion sensitivity of ternary compounds was slightly higher than that of binary compounds. From the trend of current density, it was found that Bi0.5Sb1.5Te3 had a corrosion resistance intermediate between Bi2Te3 and Sb2Te3. On the other hand, corrosion resistance was affected despite a small amount of Se substitution, and the corrosion resistance of Bi2Te2.85Se0.15 was close to or lower than that of Bi2Se3. From the observation results of the corrosion products, the trends of morphology and composition of corrosion products for Bi0.5Sb1.5Te3 or Bi2Te2.85Se0.15 were consistent with those of Sb2Te3 or Bi2Se3, respectively. From the results of x-ray photoelectron spectroscopy for the electrolyte after testing, the possibility that a corrosion product diffuses to the environment including the salt was suggested in Bi0.5Sb1.5Te3. However, the amount of dissolved corrosion product was very low, and the chemical stability of the corrosion product was not changed or improved by element substitution. 相似文献
7.
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
8.
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
9.
Thermoelectric Properties of <Emphasis Type="Italic">n</Emphasis>-Type Multiple-Filled Skutterudites
Filled skutterudites are prospective intermediate temperature materials for␣thermoelectric power generation. CoSb3-based n-type filled skutterudites have good electrical transport properties with power factor values over 40 μW/cm K2 at elevated temperatures. Filling multiple fillers into the crystallographic voids of skutterudites would help scatter a
broad range of lattice phonons, thus resulting in lower lattice thermal conductivity values. We report the thermoelectric
properties of n-type multiple-filled skutterudites between 5 K and 800 K. The combination of different fillers inside the voids of the skutterudite
structure shows enhanced phonon scattering, and consequently a strong suppression of the lattice thermal conductivity. Very
good power factor values are achieved in multiple-filled skutterudite compared with single-element-filled materials. The dimensionless
thermoelectric figure of merit for n-type filled skutterudites is improved through multiple-filling in a wide temperature range. 相似文献
10.
L. N. Lukyanova V. A. Kutasov P. P. Konstantinov V. V. Popov 《Journal of Electronic Materials》2010,39(9):2070-2073
Thermoelectric and galvanomagnetic properties of p-type solid solutions based on bismuth and antimony chalcogenides (Bi,Sb)2(Te,Se)3 have been studied to analyze the features of the figure of merit Z. The increase of Z and ZT for the p-Bi2−x
Sb
x
Te3 composition at x = 1.6 in the temperature interval of 370 K to 550 K was shown to be defined by the increase of the density-of-states effective
mass, the slope of the temperature dependence of the carrier mobility, and the reduction of the lattice thermal conductivity
for optimal charge carrier concentration. High carrier mobility and low lattice thermal conductivity provide the increase
of Z and ZT in the p-Bi2−x
Sb
x
Te3−y
Se
y
(x = 1.3, y = 0.06) solid solution in the interval from 300 K to 370 K. The growth of Z in these compositions is determined by the increase of the compression of the constant-energy ellipsoids along binary and
bisector directions, and by the change of the tilt angle Θ between the principal axes of the ellipsoids and the crystallographic
axes. 相似文献
11.
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
12.
Advanced thermoelectric (TE) cooling technologies are now receiving more research attention, to provide cooling in advanced
vehicles and residential systems to assist in increasing overall system energy efficiency and reduce the impact of greenhouse
gases from leakage by current R-134a systems. This work explores the systems-related impacts, barriers, and challenges of
using micro-technology solutions integrated with advances in nano-scale thermoelectric materials in advanced TE cooling systems.
Integrated system-level analyses that simultaneously account for thermal energy transport into and dissipation out of the
TE device, environmental effects, temperature- dependent TE and thermo-physical properties, thermal losses, and thermal and
electrical contact resistances are presented, to establish accurate optimum system designs using both p-type nanocrystalline-powder-based (NPB) Bi
x
Sb2−x
Te3/n-type Bi2Te3-Bi2Se3 TE systems and conventional p-type Bi2Te3-Sb2Te3/n-type Bi2Te3-Bi2Se3 TE systems. This work established the design trends and identified optimum design regimes and metrics for these types of
systems that will minimize system mass, volume, and cost to maximize their commercialization potential in vehicular and residential
applications. The relationships between important design metrics, such as coefficient of performance, specific cooling capacity,
and cooling heat flux requirements, upper limits, and critical differences in these metrics in p-type NPB Bi
x
Sb2−x
Te3/ n-type Bi2Te3-Bi2Se3 TE systems and p-type Bi2Te3-Sb2Te3/n-type Bi2Te3-Bi2Se3 TE systems, are explored and quantified. Finally, the work discusses the critical role that micro-technologies and nano-technologies
can play in enabling miniature TE cooling systems in advanced vehicle and residential applications and gives some key relevant
examples.
Pacific Northwest National Laboratory—operated for the U.S. Department of Energy by Battelle Memorial Institute under contract
DE-AC05-76RLO1830. 相似文献
13.
M. N. Solovan A. I. Mostovyi V. V. Brus E. V. Maistruk P. D. Maryanchuk 《Semiconductors》2016,50(8):1020-1024
n-TiN/p-Hg3In2Te6 heterostructures are fabricated by depositing a thin n-type titanium nitride (TiN) film onto prepared p-type Hg3In2Te6 plates using reactive magnetron sputtering. Their electrical and photoelectric properties are studied. Dominant charge-transport mechanisms under forward bias are analyzed within tunneling-recombination and tunneling models. The fabricated n-TiN/p-Hg3In2Te6 structures have the following photoelectric parameters at an illumination intensity of 80 mW/cm2: the open-circuit voltage is VOC = 0.52 V, the short-circuit current is ISC = 0.265 mA/cm2, and the fill factor is FF = 0.39. 相似文献
14.
P. A. Ivanov A. S. Potapov T. P. Samsonova O. Korol’kov N. Sleptsuk 《Semiconductors》2011,45(10):1306-1310
Deep-level transient spectroscopy (DLTS) has been used to study p-n junctions fabricated by implantation of boron into epitaxial 4H-SiC films with n-type conductivity and the donor concentration (8–9) × 1014 cm−3. A DLTS signal anomalous in sign is observed; this signal is related to recharging of deep compensating boron-involved centers
in the n-type region near the metallurgical boundary of the p-n junction. 相似文献
15.
16.
N. A. Abdullaev N. M. Abdullaev H. V. Aliguliyeva T. G. Kerimova G. S. Mehdiyev S. A. Nemov 《Semiconductors》2011,45(1):37-42
The temperature dependences (T = 5−300 K) of the resistivity in the plane of layers and in the direction perpendicular to the layers, as well as the Hall
effect and the magnetoresistance (H < 80 kOe, T = 0.5−4.2 K) in Bi2Te3 single crystals doped with chlorine and terbium, are investigated. It is shown that the doping of Bi2Te3 with terbium atoms results in p-type conductivity and in increasing hole concentration. The doping of Bi2Te3 with chlorine atoms modifies also the character of its conductivity instead of changing only the type from p to n. In the temperature dependence of the resistivity in the direction perpendicular to layers, a portion arises with the activation
conductivity caused by the hopping between localized states. The charge-transport mechanism in Bi2Te3 single crystals doped with chlorine is proposed. 相似文献
17.
Y. Isoda S. Tada T. Nagai H. Fujiu Y. Shinohara 《Journal of Electronic Materials》2010,39(9):1531-1535
Mg2Si1−x
Sn
x
-system solid solutions are ecofriendly semiconductors that are promising materials for thermoelectric generators in the middle
temperature range. To produce a thermoelectric device, high-performance p- and n-type materials must be balanced. In this paper, p-type Mg2.00Si0.25Sn0.75 with Li and Ag double doping was prepared by the liquid–solid reaction method and hot-pressing. Effects of Li and Ag double
doping on thermoelectric properties were investigated in the temperature range from room temperature to 850 K. All sintered
compacts were identified as single-phase solid solutions with anti-fluorite structure. The carrier concentration increased
with the double doping. The temperature dependence of resistivity of the double-doped samples was similar to that of a metal.
The seebeck coefficient increased with temperature to a maximum value and then decreased in the intrinsic region. Thermal
conductivity decreased linearly with increasing temperature, reaching a minimum near the intrinsic region, and then increased
rapidly because of the contribution of the bipolar component. The dimensionless figure of merit reached 0.32 at 610 K for
Mg2.00Si0.25Sn0.75 double-doped with Li-5000 ppm and Ag-20000 ppm. 相似文献
18.
Mg2Sn compounds were prepared by the modified vertical Bridgman method, and were doped with Bi and Ag to obtain n- and p-type materials, respectively. Excess Mg was also added to some of the ingots to compensate for the loss of Mg during the
preparation process. The Mg2Sn samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), and their power factors were
calculated from the Seebeck coefficient and electrical conductivity, measured from 80 K to 700 K. The sample prepared with
4% excess Mg, which contains a small amount of Mg2Sn + Mg eutectic phase, had the highest power factor of 12 × 10−3 W m−1 K−2 at 115 K, while the sample doped with 2% Ag, in which a small amount of eutectics also exists, has a power factor of 4 × 10−3 W m−1 K−2 at 420 K. 相似文献
19.
Tatsuya Sakamoto Tsutomu Iida Shota Kurosaki Kenji Yano Hirohisa Taguchi Keishi Nishio Yoshifumi Takanashi 《Journal of Electronic Materials》2011,40(5):629-634
The thermoelectric (TE) characteristics of Sb- and Al-doped n-type Mg2Si elemental devices fabricated using material produced from molten commercial doped polycrystalline Mg2Si were examined. The TE devices were prepared using a plasma-activated sintering (PAS) technique. To complete the devices,
Ni electrodes were fabricated on each end of them during the sintering process. To realize durable devices for large temperature
differences, thermodynamically stable Sb-doped Mg2Si (Sb-Mg2Si) was exposed to the higher temperature and Al-doped Mg2Si (Al-Mg2Si) was exposed to the cooler temperature. The devices consisted of segments of Sb-Mg2Si and Al-Mg2Si with sizes in the following ratios: Sb-Mg2Si:Al-Mg2Si = 4:1, 1:1, and 1:4. A device specimen composed solely of Sb-Mg2Si showed no notable deterioration even after aging for 1000 h, while some segmented specimens, such as those with Sb-Mg2Si:Al-Mg2Si = 1:1 and 1:4, suffered from a considerable drop in output current over the large ΔT range. The observed power generated by specimens with Sb-Mg2Si:Al-Mg2Si = 1:1 and 1:4 and sizes of 2 mm × 2 mm × 10 mm were 50.7 mW and 49.5 mW, respectively, with higher and lower temperatures
of 873 K and 373 K, respectively. For the sample composed solely of Sb-Mg2Si, a power of 55 mW was demonstrated. An aging test for up to 1000 h for the same ΔT range indicated drops in output power of between ∼3% and 20%. 相似文献
20.
Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study,
the thermoelectric properties of ternary rare-earth sulfides LaGd1+x
S3 (x = 0.00 to 0.03) and SmGd1+x
S3 (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS2 sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts
of LaGd1+x
S3 were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K−1 m−1. Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd1.02S3 at 953 K. The sintered compacts of SmGd1+x
S3 were n-type hopping conductors with a thermal conductivity of less than 0.8 W K−1 m−1. Their ZT value increased significantly with temperature. In SmGd1+x
S3, the ZT value of 0.3 was attained at 953 K. 相似文献