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排序方式: 共有632条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(8):10852-10861
Carbon cloth was used as a flexible substrate for bismuth telluride (Bi2Te3) particles to provide flexibility and improve the overall thermoelectric performance. Bi2Te3 on carbon cloth (Bi2Te3/CC) was synthesized via a hydrothermal reaction with various reaction times. After over 12 h, the Bi2Te3 particles showed a clear hexagonal shape and were evenly adhered to the carbon cloth. Selenium (Se) atoms were doped into the Bi2Te3 structure to improve its thermoelectric performance. The electrical conductivity increased with increasing Se-dopant content until 40% Se was added. Moreover, the maximum power factor was 1300 μW/mK2 at 473 K for the 30% Se-doped sample. The carbon cloth substrate maintained its electrical resistivity and flexibility after 2000 bending cycles. A flexible thermoelectric generator (TEG) fabricated using the five pairs of 30% Se-doped sample showed an open-circuit voltage of 17.4 mV and maximum power output of 850 nW at temperature difference ΔT = 30 K. This work offers a promising approach for providing flexibility and improving the thermoelectric performance of inorganic thermoelectric materials for wearable device applications using flexible carbon cloth substrate for low temperature range application. 相似文献
2.
The n-type thermoelectric Bi1.9Lu0.1Te3 was prepared by microwave-solvothermal method and spark plasma sintering. The magnetic field and temperature dependences of transverse magnetoresistance measured within temperature 2–200 K interval allow finding the peculiarities characteristic for strongly disordered and inhomogeneous semiconductors. The first peculiarity is due to appearance of linear-in-magnetic field contribution to the total magnetoresistance reflected in a crossover from quadratic magnetoresistance at low magnetic fields to linear magnetoresistance at high magnetic fields. The linear magnetoresistance can result from the Hall resistance picked up from macroscopically distorted current paths due to local variations in stoichiometry of the compound studied. The second peculiarity is that both linear magnetoresistance magnitude and crossover field are functions of carrier mobility which is in agreement with the Parish and Littlewood model developed for disordered and inhomogeneous semiconductors. An increase in the mobility due to a decrease in temperature is accompanied by an increase in the magnetoresistance magnitude and a decrease in the crossover field. Finally, the third peculiarity is related to the remarkable deviation of the total magnetoresistance measured at various temperatures from the Kohler's rule. Presence of strong inhomogeneity and disorder in the Bi1.9Lu0.1Te3 structure concluded from the magnetoresistance peculiarities can be responsible for the remarkable reduction in the total thermal conductivity of this compound. 相似文献
3.
N.A. Zhuk M.G. Krzhizhanovskaya N.A. Sekushin V.V. Kharton B.A. Makeev V.A. Belyy R.I. Korolev 《Ceramics International》2021,47(14):19424-19433
The solid solutions based on the pyrochlore-type system Bi2MgNb2-xTaxO9 were formed in the compositional range х = 0–2.0 (Bi1·6Mg0·8Nb1.6-tTatO7.2, t = 0–1.6). The Rietveld method was used to refine the structure for Bi2MgNb2-xTaxO9 (x = 0, 1.0, 2.0). The increasing tantalum content led to the slight decrease in the cubic unit cell parameters from 10.56934 (4) Å for x = 0 and 10.54607 (3) Å for x = 2 (sp.gr. Fd-3m:2). At the same time, tantalum additions suppressed grain growth in the pyrochlore ceramics during sintering and made it possible to obtain materials with an average grain size of 1–2 μm (Bi1·6Mg0·8Ta1·6O7.2). The increase in the Ta5+ concentration led to the decrease in the dielectric permeability from 104 (Bi1·6Mg0·8Nb1·6O7.2) to 20 (Bi1·6Mg0·8Ta1·6O7.2) at room temperature, while the dielectric loss tangent remained lower than 0.002, which is due to the small grain size and the high porosity of the samples. An increase in temperature has practically no effect on the values of the dielectric permittivity in the entire frequency range. The samples have weak through conductivity. The activation energies of electrical conductivity varied in the range of 0.84–1.00 eV, and the less tantalum, the lower the activation energy. The electrical properties of the samples at 200 Hz to 1 MHz are described by the simplest parallel scheme. 相似文献
4.
《Journal of the European Ceramic Society》2020,40(3):742-750
Elemental composition, crystal and grain structures, specific electrical resistivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure-of-merit of n-type grained Bi1.9Gd0.1Te3 compounds, spark-plasma-sintered at TS = 690, 720, 750, 780 and 810 K, have been studied. All the samples are highly textured along the 001 direction parallel to the pressing direction. The average grain size measured along the pressing direction is much less as compared to the average grain size measured in the perpendicular direction. A strong anisotropy in the transport properties measured along directions parallel and perpendicular to the pressing direction was found within the 290 ÷ 630 K interval. Electrical resistivity decreases and thermal conductivity increases for parallel orientation as compared to these properties for perpendicular orientation. The TS - effect on thermoelectric figure-of-merit of textured Bi1.9Gd0.1Te3 compounds has been found and analyzed. Highest thermoelectric figure-of-merit (∼0.75) was observed for sample with TS = 750 K at perpendicular orientation. 相似文献
5.
《International Journal of Hydrogen Energy》2020,45(44):23947-23953
Efficient storage of hydrogen is a key issue to establish hydrogen infrastructure. In the efforts of searching suitable hydrogen storage alloys, several systems have been explored so far. All of them suffers from some drawbacks such as low gravimetric capacity, high stability, slow sorption kinetics, etc. Lithium borohydride (LiBH4) is one of the leading contender among the hydrogen storage materials owing to its high hydrogen content of 18.5 wt%. However, its high stability needs a high operating temperature (>450 °C) for the decomposition. Recently, a thermochemical reaction between Bi2X3 and LiBH4 was observed at 120 °C while performing experiments on the anode properties of Bi2X3 (X = S, Se, & Te) for Li-ion batteries. This indicated the possibility of destabilization of LiBH4 and its low-temperature decomposition. This work presents the effect of Bi2Se3 addition to the decomposition properties of LiBH4 using XRD and XPS techniques. The first step decomposition was observed to be initiated at around 180 °C, which is much lower than 450 °C for the pristine LiBH4. A further reduction in the onset temperature is observed when the bulk Bi2Se3 is replaced by the nanosheets of this material. The mechanism of this destabilization is reported herein. 相似文献
6.
《International Journal of Hydrogen Energy》2020,45(11):6082-6089
The bismuth nanoparticles modified graphene oxide composites (Bi-NPs@GO) and bismuth nanoparticles (Bi-NPs) were prepared by a hydrothermal method. The activated aluminum/bismuth nanoparticles Bi-NPs@GO/Al and Bi-NPs/Al were prepared. Their hydrolysis reaction performance were studied. The experimental results show that the composite of aluminum and Bi-NPs@GO can react rapidly with water. The 4-h milled Bi-NPs@GO/Al composite shows better hydrogen generation performance and reacted with tap water even at 0 °C. The Bi-NPs@GO/Al composite exhibits high hydrogen generation rate at room temperature. The enhancement of aluminum hydrolysis in the composite may be due to that the addition of nano-scale Bi and graphene oxide. 相似文献
7.
Slobodan D. Dolić Dragana J. Jovanović Krisjanis Smits Biljana Babić Milena Marinović-Cincović Slavica Porobić Miroslav D. Dramićanin 《Ceramics International》2018,44(15):17953-17961
Monoclinic scheelite-type BiVO4 is currently considered as one of the most promising non-titania photocatalysts, wheras tetragonal zircon-type BiVO4 is still poorly understood. Herein, a new and simple synthetic approach was applied and nanostructured single-phase zircon-type BiVO4 was successfully prepared by a controllable ethylene-glycol colloidal route. In addition, nanostructured monoclinic scheelite-type BiVO4 powders were also fabricated through annealing of the as-prepared samples. A comparative study of the two BiVO4 polymorphs was conducted and it turned out that the novel synthetic approach had a significant impact on porosity and photocatalytic performance of zircon-structured BiVO4. All the prepared materials, as-prepared and annealed, were mesoporous, while measured values of specific surface area of some zircon-structured samples (~34?m2/g) were ~7 times higher than those reported thus far for this phase. Interestingly, for the first time, zircon-type BiVO4, previously considered to be a poor photocatalyst, exhibited a better overall performance in degradation of methyl orange compared to monoclinic scheelite-type BiVO4. Hence, it could be expected that the here-presented synthesis and observations will both arouse interest in scarcely studied tetragonal zircon-type BiVO4 and facilitate as well as speed up further research of its properties. 相似文献
8.
Li-Feng Zhu Bo-Ping Zhang Jia-Qi Duan Bo-Wei Xun Ning Wang Yu-Cheng Tang Gao-Lei Zhao 《Journal of the European Ceramic Society》2018,38(10):3463-3471
0.7BiFeO3-0.3BaTiO3 (BFO-0.3BT) ceramics were prepared to uncover the impacts of sintering temperature (TS) and dwell time (td) on the microstructure and electrical properties. With increasing the TS or td, the grain sizes increase along with the porosity decreases, which is in favor of the alignment of dipole. However, excess TS or td are inclined to cause the volatilization of Bi2O3, which deteriorates piezoelectric properties. Because of the R-T two-phase coexistence, low defect ions concentration and porosity, as well as appropriate grain size, the excellent d33?=?208?pC/N and kp?=?35.46% as well as Pr?=?28.52?μC/cm2 were achieved in BFO-0.3BT ceramics at TS?=?1000?°C and td?=?6?h. In addition,large unipolar strain 0.13% and d33*?=?256.2?pm/V also were obtained in BFO-0.3BT ceramics at TS?=?1000?°C and td?=?6?h. This research indicates that the porosity and defect ion concentration as well as grain size also play an important role in piezoelectric properties in BFO-BT ceramics. 相似文献
9.
《International Journal of Hydrogen Energy》2020,45(13):7779-7787
We report the application of plasmonic Bi nanoparticles supported rGO/BiVO4 anode for photoelectrochemical (PEC) water splitting. Nearly, 2.5 times higher activity was observed for Bi-rGO/BiVO4 composite than pristine BiVO4. Typical results indicated that Bi-rGO/BiVO4 exhibits the highest current density of 6.05 mA/cm2 at 1.23 V, whereas Bi–BiVO4 showed the current density of only 3.56 mA/cm2. This enhancement in PEC activity on introduction of Bi-rGO is due to the surface plasmonic behavior of BiNPs, which improves the absorption of radiation thereby reduces the charge recombination. Further, the composite electrode showed good solar to hydrogen conversion efficiency, appreciable incident photon-to-current efficiency and low charge transfer resistance. Hence, Bi-rGO/BiVO4 provides an opportunity to realize PEC water splitting. 相似文献
10.
《Journal of the European Ceramic Society》2020,40(2):381-385
Bi3B5+xO12+3x/2 (x = 0∼6) compounds were fabricated by a conventional solid-state reaction method. The microwave dielectric properties, sintering behaviour, crystal structure, and phase evolution of the ceramics were investigated. All samples densified at ultra-low temperatures (575∼700 °C). As x increased, the phase composition of the ceramics gradually changed from mixed Bi4B2O9 and Bi3B5O12 phases to a single Bi6B10O24 phase. The ceramic with x = 4 exhibited the best microwave dielectric properties of εr = 12.14, Q × f = 14,800 GHz, and τƒ = −72 ppm/°C at 625 °C. The microwave dielectric properties deteriorated as x increased further. Moreover, the ceramics were proven to cofire with Al and Ag, indicating that they are candidates for ultra-low-temperature cofired ceramic devices. 相似文献