共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
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
3.
Yanhua Zhang Guiying Xu Pan Ren Ze Wang Changchun Ge 《Journal of Electronic Materials》2011,40(5):835-839
Various reductants and surfactants were used to investigate their effects on the structure of Bi2Te3 nanopowders prepared via hydrothermal synthesis at 150°C for 24 h. X-ray diffraction (XRD), transmission electron microscopy
(TEM), and high-resolution transmission electron microscopy (HRTEM) were applied to analyze the phase distributions, microstructures,
and grain sizes of the as-grown Bi2Te3. The results showed that the grain sizes and morphologies of the synthesized powders were mainly related to the effects of
the reductants on the nucleation rate and the surface-adsorbed energy of the diverse surfactants on special crystal planes.
Some surfactants could control the growth of the Bi2Te3 crystals and promote one-dimensional growth of nanorods during hydrothermal synthesis. 相似文献
4.
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
5.
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
6.
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
7.
Asaithambi Suresh Krishanu Chatterjee Vijay Kr. Sharma Saibal Ganguly Kajari Kargupta Dipali Banerjee 《Journal of Electronic Materials》2009,38(3):449-452
Bi2Te3 thin films were electrodeposited at various pH values of a bismuth nitrate and tellurium oxide plating solution. Enhancement
in pH results in a decrease in grain size. Transmission electron microscopy reveals the transformation of the film morphology
from dispersed nanoparticles to connected chain-like nanostructures of Bi2Te3 as pH is increased. Electrical characterization for samples deposited in the temperature range of 300 K to 425 K shows a
fourfold increase in Seebeck coefficient, S, between its maximum and minimum value as the solution pH changes from 1 to 3.5. Such enhancement of S is attributed to the increased connectivity of the nanostructures at higher pH. 相似文献
8.
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
9.
In this work, we present the optical constants of bismuth telluride (Bi2Te3), and antimony telluride (Sb2Te3) determined using spectroscopic ellipsometry (SE). The spectral range of the optical constants is from 404 nm to 740 nm.
Bi2Te3 and Sb2Te3 films with different thicknesses were grown by metalorganic chemical vapor deposition (MOCVD). Multiple sample analysis (MSA)
technique was employed in order to eliminate the parameter correlation in the SE data analysis caused by the presence of the
overalyer on top of Bi2Te3 and Sb2Te3 films. Optical constants and thicknesses for both Bi2Te3 and Sb2Te3 overlayers were also determined. Independent Bi2Te3 and Sb2Te3 samples were used to check the results obtained. In addition, SE analysis was performed on two Sb2Te3 samples after being etched in diluted NH4OH solution in order to characterize the overlayer and confirm the reliability of the results. 相似文献
10.
Flash evaporation is used to grow Bi0.5Sb1.5Te3 films 1200 nm thick on mica substrates. The average lateral crystallite sizes in the as-grown films are ~800 nm. The (0001) plane in the crystallites is preferentially parallel to the substrate plane. After heat treatment in an argon atmosphere, the effective lateral size of crystallites in which the third-order axis is perpendicular to the substrate plane increased by a factor of 3–5. The crystallites were preferentially oriented in the substrate plane as well. The thermoelectric-power parameter of Bi0.5Sb1.5Te3 films after their heat treatment in an inert environment increased approximately twofold to values close to that of the corresponding single crystals. 相似文献
11.
Reflectance spectra of single crystals of Bi2Te3-Sb2Te3 solid solutions containing 0, 10, 25, 40, 50, 60, 65, 70, 80, 90, 99.5, and 100 mol % of Sb2Te3 have been studied in the range of 400–4000 cm−1 at the temperature T = 291 K and with orientation of the vector of the electric-field strength E perpendicular to the trigonal axis of the crystal C
3 (E ⊥ C
3). The shape of the spectra is characteristic of plasma reflection; the spectra include the features in the range 1250–3000
cm−1 corresponding to the optical band gap E
g opt. The features become more pronounced as the content of Bi2Te3 is increased to 80 mol % in the composition of the Bi2Te3-Sb2Te3 solid solution. A further increase in the content of Sb2Te3 is accompanied by discontinuities in the functional dependences of the parameters characterizing the plasma oscillations
of free charge carriers on the solid-solution composition and also by a sharp increase in E
g opt. 相似文献
12.
Single phase β-Zn4Sb3 was prepared by the application of a two-stage heat treatment, and impurity elements were doped. The undoped and doped samples
were prepared by direct melting followed by two-stage heat treatment at 450°C and 400°C after solidification of the samples
in sealed quartz ampoules. Impurity doping of the samples was performed by the addition of 1 at.% of Se, In, Pb, Te, or Bi.
The resulting samples were characterized by x-ray diffraction (XRD), differential thermal analysis (DTA), optical microscopy,
and electron probe microanalysis, and their Seebeck coefficients were determined at room temperature. The undoped samples
were determined by XRD and DTA to comprise single phase β-Zn4Sb3, while the doped samples were composed of multiple phases. From the measurements of the Seebeck coefficient, all samples
were found to be p-type and all were found to have almost the same values. These results indicate that β-Zn4Sb3 has limited solubility for these impurity elements. 相似文献
13.
Hao Cui Ishwara Bhat Brooks O'Quinn Rama Venkatasubramanian 《Journal of Electronic Materials》2001,30(11):1376-1381
In this work, we present in-situ monitoring of the growth of bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thin films as well as Bi2 Te3-Sb2Te3 superlattice using a spectroscopic ellipsometer (SE). Bi2Te3 and Sb2 Te3 films were grown by metalorganic chemical vapor deposition (MOCVD) at 350 C. A44-wavelength ellipsometer with spectral range
from 404 nm to 740 nm was used in this work. The optical constants of Bi2 Te3 and Sb2Te3 at growth temperature were determined by fitting a model to the extracted in-situ SE data of optically thick Bi2 Te3 and Sb2 Te3 films. Compared to the optical constants of Bi2 Te3 and Sb2 Te3 at room temperature, significant temperature dependence was observed. Using their optical constants at growth temperature,
the in-situ growth of Bi2 Te3 and Sb2 Te3 thin films were modeled and excellent fit between the experimental data and data generated from the best-fit model was obtained.
In-situ growth of different Bi2 Te3-Sb2 Te3 superlattices was also monitored and modeled. The growth of Bi2 Te3 and Sb2 Te3 layers can be seen clearly in in-situ SE data. Modeling of in-situ superlattice growth shows perfect superlattice growth
with an abrupt interface between the two constituent films. 相似文献
14.
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
15.
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
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.
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
18.
Ruixue Chen Qingsen Meng Wenhao Fan Liqi Wang Zhong Wang 《Journal of Electronic Materials》2011,40(5):765-768
Field-activated pressure-assisted sintering (FAPAS) was applied to sinter Bi1.2Sb4.8Te9 thermoelectric materials under different conditions, including no-current sintering (NCS), low-density current sintering
(LCS), and high-density current sintering (HCS). The effect of the current density on the final thermoelectric performance
of the products was investigated. Applying a higher-density electric current and shorter dwell time can improve the thermoelectric
performance of the sample by increasing its electric conductivity and decreasing its thermal conductivity. The maximum figure
of merit ZT values of the NCS, LCS, and HCS samples were 0.46, 0.48, and 0.57, respectively. Therefore, applying a high-density electric
current in the sintering process may be an effective way to obtain Bi1.2Sb4.8Te9 thermoelectric material with high ZT value. 相似文献
19.
L. D. Ivanova Yu. V. Granatkina L. I. Petrova I. Yu. Nikhezina A. G. Malchev V. V. Alenkov S. A. Kichik A. A. Melnikov 《Semiconductors》2017,51(8):1002-1004
The thermoelectric properties of n-type Bi2Te2.4Se0.6 solid solution prepared by the vacuum hot pressing of powder mixtures with different particle sizes are investigated. The powders were prepared by the mechanical grinding of ingots and melt spinning. The microstructure and fracture pattern of a sample cleavage surface are analyzed using scanning electron microscopy and optical microscopy. The thermoelectric characteristics (the Seebeck coefficient, electrical conductivity, and thermal conductivity) are measured at room temperature and in the temperature range of 100–700 K. 相似文献
20.
Wein-Duo Yang Yen-Hwei Chang Chia-Chia Huang Yu-Chung Chen 《Journal of Electronic Materials》2009,38(3):460-467
Highly sensitive CO gas sensors based on heterocontacts of ZnO:Al on La0.8Sr0.2Co0.5Ni0.5O3 (LSCNO) were fabricated successfully. La0.8Sr0.2Co0.5Ni0.5O3 thin films were coated on (100) silicon wafers by a sol-gel method including the Pechini process followed by a spin-coating
procedure. Then, ZnO:Al films prepared by radiofrequency (RF) magnetron sputtering at various oxygen partial pressures and
deposited on as-deposited La0.8Sr0.2Co0.5Ni0.5O3 films were investigated. The results revealed that the CO sensing ability of the film prepared with the ratio of O2/Ar = 5/5 (ratio of volume flow rate) was the worst, owing to the highest (002) plane orientation in the ZnO:Al film. In contrast,
the ZnO:Al film prepared with O2/Ar = 3/7 exhibited better CO sensitivity. Furthermore, all two-layer samples showed higher CO sensitivities than single-layer
samples. The CO sensitivity of ZnO:Al/La0.8Sr0.2Co0.5Ni0.5O3 thin film was 45% for 500 ppm CO at a sensing temperature of 200°C. 相似文献