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Search Results: 1 - 10 of 60 matches for " telluride "
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Electrochemical Deposition and Optimization of Thermoelectric Nanostructured Bismuth Telluride Thick Films  [PDF]
Hesham M. A. Soliman, Abdel-Hady B. Kashyout
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.36079
Abstract: Bismuth telluride thick films are suitable for thermoelectric (TE) devices covering large areas and operating at small-to-moderate temperature differences (20 - 200 K). High efficiency and high coefficient of performance (COP) are expected to be achieved by using thick films in some cooling applications. Bismuth telluride thick films fabrication have been achieved with Galvanostatic and Potentionstatic deposition. Stoichiometric bismuth telluride thick film was obtained by Galvanostatic deposition at current density of 3.1 mAcm-2. Bismuth telluride films with average growth rate of 10 µmh-1 and different composition were obtained. Effects of current density and composition of electrolyte in Galvanostatic deposition were studied. The current density affected the film compactness, where films deposited at lower current density were more compact than those deposited at higher current density. The morphology of the films did not depend on the current density, but chemical composition was observed when different composition of electrolyte was used. Effects of distance between electrodes, composition of electrolyte solution, and stirring in Potentionstatic deposition were studied. The shorter the distance between electrodes, the higher the electric field, thus the higher current density was applied and the deposited film was less compact. The current density increased more rapidly with stirring during electrodeposition which leads to less compact film. Through this study, films electrode-posited from solution containing 0.013 M Bi(NO3)3.5 H2O, 0.01 M TeO2 and 1 M HNO3 at 3.1 mA cm-2 for 6 hours without stirring and with interelectrode distance of 4.5 cm were free-standing with average film thickness of 60 µm and optimum film composition of Bi2Te3. The crystallite size of the later films was found to be around 4.3 nm using Scherrer’s equation from XRD patterns. Also, negative Seebeck coefficient for the same samples was revealed with an average value of -82 μV.K-1.
Porous Thermoelectric Materials
Hiroshi Julian Goldsmid
Materials , 2009, DOI: 10.3390/ma2030903
Abstract: Thermoelectric materials are sometimes prepared using a sintering process in which the achievement of a high density is often one of the objectives. However, it has recently been shown that the introduction of a highly porous material is desirable in synthetic transverse thermoelements. Porosity may also be an advantage in conventional longitudinal thermoelectric modules in which a high thermal flux density creates problems, but heat transfer within the pores can degrade the thermoelectric figure of merit. The amount of this degradation is calculated and it is shown that it can be small enough to be acceptable in practical devices.
Studying Thermoelectric Power Behaviors of Bi2Te3 Nanoparticles Prepared by Thermal Evaporation  [PDF]
Sayed Mohammad Elahi, Hana Nazari, Laya Dejam, Hamid Reza Gorji
Open Journal of Applied Sciences (OJAppS) , 2016, DOI: 10.4236/ojapps.2016.66034
Abstract: Thin films of Bismuth Telluride (Bi2Te3) are prepared by thermal evaporation from nanopowders on the glass substrates. The XRD patterns of films show that all the films are polycrystalline and the crystalline increased by annealing temperature. Measuring of the thermoelectric power of thin films in the temperature range 300 to 380 K shows that Seebeck Coefficients have both negative and positive values, indicating that the films have both n-type and p-type conductivity. The re-crystallization of films is done by annealing from 130°C to 175°C and Seebeck Coefficient varied from -150 to 100 μV/K.
Template-Free Bipotentiostatic Deposition of Thermoelectric BixTey Nano Arrays  [PDF]
Xin Bo, Feng Wang, Chuan Zhao
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51001
Abstract:
Monodispersed Bi-Tenano arrays are achieved via template-free bipotentiostatic deposition. The diameter and length of individual nanorod is ~80 nm and ~250 nm respectively. The electrodeposition process is demonstrated to follow a two-step mechanism: an instantaneous reductive potential is applied to form dispersive nuclei, then a reverse oxidative potential strips partial Bi atoms to prevent further cross-growth. Repeatedly, the nano arrays film is obtained eventually. The thermoelectric properties of the obtained Bi-Tenano arrays such as electrical resistance, carrier density, Seebeck coefficient and power factor are measured to be 2.438 × 10-4?Ω·m, 4.251 × 1020 cm-3, -25.892 μV·K-1, 2.750 × 10-6 W·m-1·K2, respectively.
Power generation from thermoelectric system-embedded Plexiglas for green building technology
Salman Bin Inayat,Muhammad Mustafa Hussain
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0139-z
Abstract: Thermoelectric materials embedded through or inside exterior glass windows can act as a viable source of supplemental power in geographic locations where hot weather dominates. This thermoelectricity is generated because of the thermal difference between the high temperature outside and the relatively cold temperature inside. Using physical vapor deposition process, we experimentally verify this concept by embedding bismuth telluride and antimony telluride through the 5 mm Plexiglas to demonstrate 10 nW of thermopower generation with a temperature gradient of 21 °C. Albeit tiny at this point with non-optimized design and development, this concept can be extended for relatively large-scale power generation as an additional power supply for green building technology.
Pb1-xMnxTe and PbTe1-xSx compounds and their optical properties
JELENA TRAJIC,ALEKSANDAR GOLUBOVIC,MAJA ROMCEVIC,NEBOJSA ROMCEVIC
Journal of the Serbian Chemical Society , 2007,
Abstract: Pb1-xMnxTe crystals were obtained by the Bridgman method and PbTe1-xSx crystals were grown by the vapour–liquid–solid technique. The tructural properties of Pb1-xMnxTe (x £ 0.10) and PbTe1-xSx (x £ 0.05) were observed by X-ray powder diffraction analysis. The optical properties were studied by Raman spectroscopy as a function of temperature. Measurements on these samples of different composition gave information about the Mn and S position in the lattice (off-centering), their clustering and ordering, as well as of the influence of these processes on the crystal structure and properties. The model of phonon behaviour based on the Random Element Isodisplacement model was applied, and it was found that the phonons in PbTe1-xSx show a two-mode behaviour (each TO-LO mode pair of the end members degenerates to an impurity mode), while the Pb1-xMnxTe optical phonons have a ntermediate one-two-mode behaviour (the LO-mode frequency shifts continuously from PbTe to MnTe, while the other modes resemble the two-mode case).
Dendritic tellurides acting as antioxidants
Huaping Xu,Yapei Wang,Zhiqiang Wang,Junqiu Liu,Smet Mario,Dehaen Wim
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-2107-z
Abstract: We have described the synthesis of a series of poly(aryl ether) dendrimers with telluride in the core and oligo(ethylene oxide) chains at the periphery which act as glutathione peroxidase (GPx) mimics. These series of compounds were well characterized by 1H-NMR, 13C-NMR and ESI-MS. Using different ROOH (H2O2, cumene hydroperoxide) for testing the antioxidizing properties of these compounds, we have found that from generation 0 to 2, the activity of the dendritic GPx mimics first decreased and then increased. This can be explained on the basis of a greater steric hindrance, going from generation 0 to 1, and stronger binding interactions going from generation 1 to 2. In other words, there exists a balance between binding interactions and steric hindrance that may optimize the GPx activity.
Fabrication and Characterization of PLD-Grown Bismuth Telluride (Bi2Te3) and Antimony Telluride (Sb2Te3) Thermoelectric Devices  [PDF]
Ibrahim M. Abdel-Motaleb, Syed M. Qadri
Journal of Electronics Cooling and Thermal Control (JECTC) , 2017, DOI: 10.4236/jectc.2017.73006
Abstract: We report on the fabrication and characterization of multi-leg bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thermoelectric devices. The two materials were deposited, on top of SiO2/Si substrates, using Pulsed Laser Deposition (PLD). The SiO2 layer was used to provide insulation between the devices and the Si wafer. Copper was used as an electrical connector and a contact for the junctions. Four devices were built, where the Bi2Te3 and Sb2Te3 were deposited at substrate temperatures of 100°C, 200°C, 300°C and 400°C. The results show that the device has a voltage sensitivity of up to 146 μV/K and temperature sensitivity of 6.8 K/mV.
The First Lanthanide Telluride-Bromide: La3Te4Br, a Valence Compound
Markus Larres,Anja-Verena Mudring,Gerd Meyer
Crystals , 2011, DOI: 10.3390/cryst1010015
Abstract: The first ternary lanthanide telluride-bromide La3Te4Br was obtained from a mixture of LaTe and LaBr3 (in the presence of iridium) in a sealed tantalum container at elevated temperatures. The crystal structure (orthorhombic, Pnma, a = 1634.3(2), b = 435.0(1), c = 1426.6(2) pm, Z = 4, R1 (I0 > 2s(I0)) = 0.0349) is built from dicapped trigonal prisms of tellurium and bromine atoms surrounding lanthanum in two different ways. The dicapped trigonal prisms are connected via common edges to a threedimensional structure, in the same fashion as is known for the binary U3Te5. La3Te4Br is a valence compound according to (La3+)3(Te2-)4(Br-) and one out of three lanthanide telluride-halides known to date.
Mechanical and Dielectric Properties of InTe Crystals  [PDF]
Teena Mathew, Ayyappacharuparambil Gopalanachary Kunjomana, Keelapattu Munirathnam, Kunnath Appukuttan Chandrasekharan, Muthukrishnan Meena, Chelliah Kamalakshiammal Mahadevan
Crystal Structure Theory and Applications (CSTA) , 2012, DOI: 10.4236/csta.2012.13015
Abstract:

The mechanical properties of indium telluride (InTe) crystals grown by the Bridgman technique were investigated at room temperature using a Vickers hardness tester. The microhardness is observed to vary nonlinearly with the applied load, 10 - 100 g. The cleaved ingots are found to have high value of microhardness (222.44 kg/mm2 at a load of25 g), which reflects an appreciable degree of strength due to their covalent bonding and homogeneity. The studies revealed that the dislocations in the grown crystals offered a resistance to fresh dislocations due to interaction. At higher loads, plastic deformation induces by slip, exhibiting a decrease in hardness from the peak value. The dielectric constant and dielectric loss of indium telluride crystals were evaluated in the frequency range, 1 kHz - 1 MHz for different temperatures (35oC - 140oC). The frequency dependence of AC conductivity was analyzed as a function of temperature. The effect of temperature and frequency on the dielectric response of InTe crystals has been assessed on their cleavage faces and the obtained results are discussed.

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