Browsing by Subject "Bismuth compounds"
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Item Radioluminescence and thermoluminescence of rare earth element and phosphorus-doped zircon(Mineralogical Society of America, 2000) Karali T.; Can N.; Townsend P.D.; Rowlands A.P.; Hanchar J.M.The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare earth element (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE3+ states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-earth lines of the same element. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare earth ions. The temperature shifts of the peaks are considerable, up to 200°, and much larger than those cited in other rare-earth-doped crystals of LaF3 and Bi4Ge3O12. The data clearly suggest that the rare-earth ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE3+ ions.Item Microstructure and Electrical Conductivity of ZnO Addition on the Properties of (Bi0.92Ho0.03Er0.05)2O3(Springer New York LLC, 2016) Ermiş I.; Çorumlu V.; Sertkol M.; Öztürk M.; Kaleli M.; Çetin A.; Turemiş M.; Arı M.The solid electrolyte is one of the most important components for a solid oxide fuel cell (SOFC). The various divalent or trivalent metal ion-doped bismuth-based materials exhibit good ionic conductivity. Therefore, these materials are used as electrolytes in the SOFC. In this paper, the samples of (Bi0.92−xHo0.03Er0.05)2O3 + (ZnO)x solutions with a 0 ≤ x ≤ 0.2 molar ratio are synthesized by the solid state reaction method. The detailed structural and electrical characterizations are investigated by using x-ray diffraction (XRD), alternating current electrochemical impedance spectroscopy, and scanning electron microscopy (SEM). The XRD patterns of all samples are indexed on a monoclinic symmetry with a P21/c space group. In addition, the rietveld parameters are determined by using the FullProf software program. The impedance measurements of the samples are obtained at the 1 Hz to 20 MHz frequency range. The impedance value of the pellets increases with temperature. Based on the impedance results, it is found that the contribution of grain (bulk) is more than a grain boundary in terms of conductivity, which permits the attribution of a grain boundary. The ionic conductivity decreases with an increasing amount of Zn contribution. The value of highest electrical conductivity among all samples is calculated as 0.358 S cm−1 at 800°C for undoped (Bi0.92Ho0.03Er0.05)2O3. © 2016, The Minerals, Metals & Materials Society.Item Thermoluminescence studies of Nd doped Bi4Ge3O12 crystals irradiated by UV and beta sources(Elsevier Ltd, 2016) Karabulut Y.; Canimoglu A.; Ekdal E.; Ayvacikli M.; Can N.; Karali T.Thermoluminescence (TL) glow curves of pure and rare earth doped bismuth germanate (BGO) were investigated under UV and beta radiation. The glow curves of pure BGO crystal present different patterns for both kinds of radiation. The TL glow curves of BGO crystals doped with Nd ions are similar to that of pure BGO under UV radiation. The kinetic parameters, kinetic order (b), activation energy (E) and frequency factor (s) of the TL glow curves of pure BGO crystal have been determined by peak shape method. Activation energies of 3 peaks obtained by PS were found to be 1.81, 1.15 and 1.78, respectively. © 2016 Elsevier Ltd.Item Cost-effective chemical solution synthesis of bismuth telluride nanostructure for thermoelectric applications(Institution of Engineering and Technology, 2018) Mamur H.; Dilmac O.F.; Korucu H.; Bhuiyan M.R.A.In this work, the bismuth telluride (Bi2Te3) nanostructure for thermoelectric applications was successfully synthesised by a new cost-effective chemical solution process. Firstly, the metal solutions of bismuth (III) nitrate pentahydrate and tellurium dioxide were mixed together at room temperature with adjusting the hydrodynamic atmosphere and introduced the sodium hydroxide. After that, different characterisation parameters, such as X-ray diffraction, atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray, and transverse electron microscopy (TEM) were obtained. Then, the average crystalline size of the Bi2Te3 nanostructure was found 23 nm. According to these obtained results, the materials consist of every specimen in nano range dimension in AFM studies. The elemental of Bi and Te were arranged with their quite stoichiometric atomic ratio observed by SEM. Ultimately, the TEM micrographs showed that the powders exhibited an aggregate phenomenon, and the primary crystalline size was about low dimension. © 2018 Institution of Engineering and Technology. All rights reserved.Item A review on bismuth telluride (Bi2Te3) nanostructure for thermoelectric applications(Elsevier Ltd, 2018) Mamur H.; Bhuiyan M.R.A.; Korkmaz F.; Nil M.Bismuth Telluride (Bi2Te3) is basically known as an efficient thermoelectric material. Nowadays, it has been attracted a great deal of interest in energy harvesting, chip cooling, chip sensing and other field of material science because of its potential applications. In order to produce Bi2Te3 nanostructure, a number of methods such as solvo and hydro thermal, refluxing, straight forward arc–melting and polyol methods have been employed. Among of them, the solvothermal method has been one of the most common methods to fabricate Bi2Te3 nanostructure in thermoelectric applications. But the development of device–quality material has been a challenging task for the researchers, yet. For this reason, this paper provides a review of current research activities on Bi2Te3 nanostructure growth by several methods and its characterization through theoretical and analytical aspects. Moreover, the paper handles a systematic and intensive research work to develop and understand the materials in nanostructure forms. © 2017 Elsevier LtdItem A review on performance evaluation of bi2te3-based and some other thermoelectric nanostructured materials(Bentham Science Publishers, 2021) Bhuiyan M.R.A.; Mamur H.; Dilmaç Ö.F.Background: Future sustainable energy industrialization is a green energy source that has a lower circumstantial impact than traditional energy technologies. The advancement of new energy generation is important to expand the share of renewable energy sources. Objective: Worldwide, for the next generation, future energy demand may be fulfilled by using one of the renewable energy sources such as thermo electricity. Methods: The bismuth telluride–based (Bi2Te3-based) nanostructure material in thermo electricity still has a major part of applications. It is known as the most prospective TE device manufactured from a research arena towards successful commercialization. Results: The Bi2Te3-based nanostructure material is now on commercialization stages that it has some limitations. In order to find out the future direction of research and development of this mate-rial, the material will face a challenging way. Conclusion: The review paper provides an effective approach to overcome the limitation of Bi2Te3-based nanostructure. Moreover, in this review paper, the performance evaluation with existing Bi2Te3-based nanostructure and some other TE materials will be discussed in detail. © 2021 Bentham Science Publishers.Item Growth and characterization of Bi2Te2.70Se0.30 nanostructured materials by using a cost-effective chemical solution route(Elsevier B.V., 2023) Bhuiyan M.R.A.; Korucu H.; Mamur H.; Haque M.M.A chemical solution route was employed to successfully synthesize single-phase Bi2Te2.70Se0.30 nanostructured powders at room temperature, ensuring minimal contamination. The synthesized powders underwent a comprehensive analysis using a range of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), ultraviolet-visible (UV) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, atomic-force microscopy (AFM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The temperature-dependent behaviors of electrical conductivity and the Seebeck coefficient were also explored. The findings revealed that the synthesized powders displayed consistent spherical morphology, with an average diameter of 68.42 nm. Additionally, they exhibited a band gap energy of 0.615 eV. This research highlights the significant improvement achieved by incorporating selenium into the Bi2Te2.70Se0.30 materials through this synthesis process. The EDAX analysis confirmed the stoichiometric atomic ratio of bismuth (Bi), tellurium (Te), and selenium (Se) elements. Furthermore, the TEM images revealed the presence of agglomeration within the powders, demonstrating a primary crystalline size characterized by relatively small dimensions. The emergence of a pronounced exothermic peak at around 650 K signaled the commencement of oxidation for the Bi2Te2.70Se0.30 material. In electrical measurement, a synergy was achieved between heightened electrical conductivity and a well-matched Seebeck coefficient, with the goal of enhancing energy conversion efficiency in TE applications. These findings demonstrate the potential of the synthesized powders for producing nanostructured thermoelectric (TE) materials with controlled grain sizes, which are essential for the fabrication of high-performance thermoelectric generators (TEGs). © 2023 The AuthorsItem Optimizing the performance of Bi2Te3 TECs through numerical simulations using COMSOL multiphysics(Elsevier B.V., 2024) Hasan M.K.; Haque M.M.; Üstüner M.A.; Mamur H.; Bhuiyan M.R.A.Manufacturers need to determine the best geometries for thermoelectric coolers (TECs) to achieve optimal performance. In this study, we employed the COMSOL Multiphysics software to simulate the performance enhancement of Bi2Te3 TEC. The TEC is constructed with alumina (Al2O3), copper (Cu), and bismuth telluride (Bi2Te3) materials. In particular, Al2O3 acts as an electric insulator for the top and bottom layers, Cu functions as a conductor, and Bi2Te3 serves as the p- and n-type thermoelectric (TE) legs between the Cu layers. The study examined how different TE leg heights (1.5 mm, 2 mm, and 2.5 mm) and shapes (square and rectangular) affected the TEC's performance. It looked at various factors, such as temperature gradient, electric potential, normalized current density, and total net energy rate. Additionally, the thickness effects of the insulator, conductor, and the TE leg pitch of the TEC have also been investigated. According to the obtained results, it has been determined that the square type of leg geometry has provided the best performance among the tested geometries, and it has been recommended that its leg geometry be 1.00 mm × 1.00 mm × 1.5 mm, the thickness be 0.375 mm for Al2O3 and 0.125 mm for Cu, and the pitch be 0.50 mm, as they are expected to yield satisfactory performance. The research study involved obtaining performance parameters for 18 TE elements utilized in the fabrication of TEC. The TEC-simulated results revealed the following performance metrics: ΔTmax = 73.94 K, Umax = 2.52 V, Imax = 3.00 A, Qmax = 4.42 W, R = 0.84 Ω, and Z = 0.002377 1/K. © 2024 The Authors