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Journal of Alloys and Compounds
Elsevier Science S.A.
Journal of Alloys and Compounds

Elsevier Science S.A.

0925-8388

Journal of Alloys and Compounds/Journal Journal of Alloys and CompoundsSCIISTPEI
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    Photoconductive PbSe thin films and the role of potassium iodide

    Harrison J.T.Gupta M.C.
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.The PbSe thin films are sensitized by oxidation and iodization process to improve the infrared photoresponse enabling higher performing photodetectors and photovoltaic devices. Iodine is widely used for PbSe sensitization, and it influences the thin film morphology and also forms a PbI2 passivation layer. Potassium Iodide (KI) has been used as an additive in chemical bath deposited films of PbSe since 1959 and continues to this day. This work aims to better understand the role of KI in PbSe films as it improves MWIR photoresponse by as much as 300% compared to samples without KI. In this research paper, we show that low levels of KI (180 mMol) densify the PbSe film, increase grain size, reduce film stress/cracking, and improve IR absorption (proportional to dose). The transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies show thermal annealed PbSe films with KI convert round equiaxed grains to highly faceted grains coated with PbI2 ranging from 3 to 10 nm, throughout the film. The dense PbSe grains encapsulated in PbI2 lead to a more uniform PbSeO3 layer following thermal oxidation. The electrical resistance versus temperature measurements shows a strong phase transition occurs at 220 °C only for samples with KI. X-ray photoelectron spectroscopy studies confirm that PbSe films with KI annealed in an argon atmosphere at 460 °C have a surface layer of PbI2, and no potassium was detected, suggesting desorption or diffusion of potassium into the PbSe grains. PbSe films with KI showed 30x higher electrical resistance (RD) under dark conditions, leading to reduced carrier concentration (lower dark current) and improved photoresponse without impacting electron mobility. In summary, we have clarified the role of KI in PbSe thin films and how it can be used to improve the infrared photoresponse.

    Boosting oxygen electrode kinetics by addition of cost-effective transition metals (Ni, Fe, Cu) to platinum on graphene nanoplatelets

    Mladenovic D.MiljanicSljukic B.Das E....
    11页
    查看更多>>摘要:? 2022 Elsevier B.V.Pt and Pt-M (M = Ni, Fe, Cu) nanoparticles supported on graphene nanoplatelets (GNPs) were synthesized by simultaneous supercritical carbon dioxide deposition method. Morphology analysis by TEM revealed the formation of metal nanoparticles of 2–3 nm size uniformly distributed over GNPs, while XPS was used to determine their oxidation states. Four materials were tested as electrocatalysts for ORR and OER in unitized regenerative fuel cells and rechargeable metal-air batteries. PtFe/GNPs exhibited favorable ORR kinetics in terms of the highest diffusion-limited current density, the lowest Tafel slope, and a high number of exchanged electrons (n = 3.66), which might be attributed to its high double-layer capacitance and, thus, high electrochemically active surface area. Furthermore, this material performance was comparable to that of commercial Pt/C electrocatalyst containing double the amount of Pt. The same material showed the best performance toward OER as evidenced by the highest current density, the lowest value of exchange current density, and overpotential to reach a current density of 10 mA cm-2, as well as the lowest Tafel slope.

    Ni2P@MoS2/CC catalysts with heterogeneous structure are used for highly efficient electrolysis of water for hydrogen evolution

    Dai Y.Chen W.Li X.Guan J....
    8页
    查看更多>>摘要:? 2022 Elsevier B.V.Efficient and inexpensive electrocatalysts play an important role in electrolysis of water and hydrogen evolution reaction. The catalytic activity of electrocatalyst can be improved by adjusting the electronic structure and increasing the active center. In this study, Ni2P nanosheets were grown on carbon cloth through straightforward solvothermal, and tiny MoS2 nanosheets were uniformly covered on Ni2P nanosheets by in-situ growth method to form heterogeneous electrocatalyst (Ni2P @ MoS2/CC). The results show that Ni2P @ MoS2/CC had more active sites than Ni2P/CC and MoS2/CC catalysts. In addition, the interface interaction based on heterogeneous structure promotes its charge transfer kinetics. In alkaline electrolyte, Ni2P @ MoS2/CC electrocatalyst had good HER performance. At a current density of 10 mA cm?2, the overpotential was 99 mV, and the Tafel slope was 97 mV dec?1. In addition, the catalyst showed excellent electrochemical stability, with no significant loss of activity after 2000 cyclic voltammetry tests and 50 h i-t tests.

    The influence of Ni and Zr additions on the hot compression properties of Al-SiCp composites

    Awe S.A.Lattanzi L.Etienne A.Li Z....
    12页
    查看更多>>摘要:? 2022 The Author(s)The present work investigates different additions of nickel and zirconium to the matrix alloy of Al-SiC metal matrix composites to enhance their high-temperature performance. These composites are promising for the demand for lightweight solutions for automotive components like brake discs. In such components, the compression behaviour at elevated temperatures is crucial. The resulting properties were combined with microstructural analysis. Ni additions led to a continuous improvement of the mechanical response, but the same result did not hold for the Zr additions. The interaction of SiC particles, eutectic silicon, and eutectic Ni-based phases led to a 44 % increment of the activation energy.

    Characterization of hot workability of Ti-6Cr-5Mo-5V-4Al alloy based on hot processing map and microstructure evolution

    Li C.Huang L.Guo S.Zhao M....
    13页
    查看更多>>摘要:? 2022 Elsevier B.V.Ti-6Cr-5Mo-5V-4Al (Ti-6554) alloys with excellent comprehensive properties are expected to become the preferred material for large-scale parts in the aviation field. However, the processing parameters of large-scale parts have a significant impact on the microstructure, so it is necessary to optimize the hot working process to improve the comprehensive mechanical properties of the alloy. In this paper, hot compression experiments of Ti-6554 alloy were carried out in the temperature range from 680 to 830 ℃ and strain rate range from 0.001 to 10 s?1. The hot workability of the Ti-6554 alloy was studied based on the hot processing map and microstructure evolution. The Arrhenius constitutive model of the two phase region and single phase region was established. It was found that the thermal activation energy was higher at high value in the adopted range of strain rate, and the average thermal activation energy gradually decreased with raising the strain. The peak efficiency in the hot processing map occurred at 680 ℃/0.001 s?1 and 770 ℃/0.001 s?1 with efficiency values of 0.47 and 0.48, respectively. The instability regions were mainly concentrated at a high value in the adopted range of strain rate, and the typical instability phenomenon was flow localization. With raising the strain rate and temperature, the volume fraction and average size of the α phase decreased due to the dynamic phase transformation. Dynamic recovery (DRV) was the major deformation mechanism at low temperatures and low strain rates. The deformation mechanism gradually changed to DRX with the increase of temperature and strain rate. However, the increase of temperature at a higher strain rate could not improve the level of dynamic recrystallization (DRX). Based on electron backscatter diffraction (EBSD) characterization, the DRX types of the β phase were determined to be discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX). DDRX mainly occurred at high temperatures and low strain rates. Furthermore, the spheroidizing mechanism of the equiaxed α phase was also analyzed. First, under the action of compressive stress, the aspect ratio of the equiaxed α phase gradually increased and became the lamellar α phase. Subsequently, the low angle grain boundaries (LAGBs) gradually changed to high angle grain boundaries (HAGBs), accompanied by wedging of the β phase. Finally, the spheroidization process was completed.

    Study of RBO3-ScBO3 phase diagrams and RSc3(BO3)4 orthoborates (R = La, Pr and Nd)

    Jamous A.Y.Svetlichnyi V.A.Kuznetsov A.B.Kokh K.A....
    10页
    查看更多>>摘要:? 2022 Elsevier B.V.RBO3 – ScBO3 diagrams (R = La, Pr and Nd) were investigated by the solid state synthesis and DSC methods. In these systems the solid solutions based on RSc3(BO3)4, RBO3 and ScBO3 were identified. The single crystals of RSc3(BO3)4 were grown by spontaneous crystallization method from LiBO2-LiF flux. The borates containing Pr and Nd have typical luminescence in the red/IR range which correlated to Pr3+: 3P0 → 3H6, 1D2 → 3H4 (~ 620 nm), and 3P0 → 2F2, 1D2 → 3H5 (~ 655 nm) and Nd3+ electron transitions 4F3/2 → 4I9/2 (875 nm) and 4F3/2 → 4I11/2 (1055 nm). The luminescence intensity strongly depends on the concentration of the fluorophores. In addition the SHG efficiency (for radiation of Nd:YAG laser, 1064 nm) for grown PrSc3(BO3)4 crystals was found to be 1.85 times higher (deff) than for KDP revealing its high potential for various NLO applications.

    Low temperature lithium-ion batteries electrolytes: Rational design, advancements, and future perspectives

    Yang H.Wu J.Fang J.Zhu M....
    18页
    查看更多>>摘要:? 2022 Elsevier B.V.Lithium-ion batteries (LIBs) are considered as irreplaceable energy storage technologies in modern society. However, the LIBs encounter a sharp decline in discharge capacity and discharge voltage in low temperature environment (< 0 °C), which cannot meet growing demands for portable electronics and electric vehicles at low temperature. In particular, the LIBs experience the dramatical decrease of lithium-ion conductivity in electrolyte and sluggish charge transfer process within the electrode at low temperature. Therefore, rational design on the low-temperature electrolyte is critical important for achieving excellent performance of LIBs to broaden their application scenarios at low-temperature. To this end, in this review, we firstly discuss the origination on the LIBs performance degradation at low temperature. Then, the corresponding strategies on rational tailoring traditional electrolytes (lithium salts and the solvents, including carbonate-based, carboxylate-based, ether-based and ionic liquid solvent), and the new emerging electrolytes (e.g., locally high concentrated electrolyte, liquefied gas electrolyte and polymer electrolyte) towards low-temperature LIBs are introduced. Finally, the remaining challenges and future perspectives for low-temperature LIBs are presented. It is expected that this review will shed fresh light on electrolyte design for low-temperature LIBs and accelerate widespread application of LIBs for low temperature environment.

    Compositional dependence of structural, magnetic and spin-phonon coupling properties in Fe2?xGaxO3 (x = 0.6–1.2) system with orthorhombic symmetry

    Lone A.G.Bhowmik R.N.
    15页
    查看更多>>摘要:? 2022 Elsevier B.V.A combined technique of mechanical alloying and heat treatment has been used to prepare the polycrystalline samples of Fe2?xGaxO3 (x = 0.6–1.2) system in orthorhombic phase. It has been possible to reduce the sintering temperature by ~350 °C for stabilizing the orthorhombic phase in comparison to the temperature reported in literature. The Rietveld refinement of X-ray diffraction patterns indicated the distribution of Ga and Fe atoms in the Ga1, Ga2, Fe1 and Fe2 sites of the lattice structure. A linear variation of the lattice parameters with Ga/Fe content showed application of Vegard's law. The temperature-dependent magnetization measurements confirmed ferrimagnetic order of Fe spin moments. The ferrimagnetic transition temperature (TC) has decreased from 320 K to 100 K with the increase of Ga content in the range of x = 0.6–1.2. Temperature-dependent Raman spectroscopy data ruled out any structural phase transition at TC, but an anomalous behaviour of the position and width of the peaks of Raman active phonon modes near to TC confirmed a strong spin–phonon coupling in the material. The spin–phonon coupling strength (η) for the A9 mode has been found around 1.64 cm?1 for x = 1 and 3.34 cm?1 for x = 0.8, and η for the A21 mode has been found around 2.12 cm?1 for x = 1 and 3.28 cm?1 for x = 0.8. The spin-phonon coupling strength has been diluted in the samples with higher content of Ga. The experimental results indicated that the variation of Ga/Fe content and its distribution in lattice sites determine the ferrimagnetic properties, magnetic anisotropy and spin-phonon coupling in Fe2?xGaxO3 system. The results are expected to be useful for understanding the spin-phonon coupling in multiferroic-magnetoelectric materials with magnetic and electric transitions near to room temperature.

    Enhancing the electrochemical hydrogen evolution of CoP3/CoMoP nanosheets through the support of black TiO2?x nanotube arrays

    Zhang T.Yang T.Li B.Gao W....
    8页
    查看更多>>摘要:? 2022 Elsevier B.V.The hydrogen evolution reaction (HER) is a crucial part of renewable energy application. It is still a huge challenge to enhance the intrinsically catalytic performance of non-noble metal-based electrocatalysts. Transition metal phosphides (TMPs) have been recognized as the effective HER catalysts. However, TMPs nanosheets suffer from low activity for water dissociation, which prohibits the HER properties of electrocatalyst in alkaline solution. Herein, a structure that decorates CoP3/CoMoP nanosheets on the black TiO2?x nanotube arrays substrate has been designed. The oxygen vacancy in the black TiO2?x substrate is expected to play an important role in the water dissociation and therefore enhance the initial Volmer step during HER. What's more, the nanotube structure of black TiO2?x substrate provides a larger surface area for CoP3/CoMoP nano sheets decoration, the number of active sites enhanced during the reaction, resulting in higher HER performance. Experimental results demonstrate that CoP3/CoMoP/TiO2?x@Ti possesses much improved HER properties with a low overpotential of 143 mV at 10 mA?2 and a Tafel slope of 61 mV dec?1, it also provides long-term durability without significant degradation for 48 h. This work develops a low-cost and valuable approach to enhance the HER activity of transition metal phosphides in alkaline electrolytes.

    Investigation on microstructure transition and electrical behavior in (1-x)Bi4Ti3O12/xBi4.5K0.5Ti4O15 lead-free composites

    Wang L.G.Yao M.W.Zhu C.M.Yu G.B....
    11页
    查看更多>>摘要:? 2022 Elsevier B.V.The lead-free (1-x)Bi4Ti3O12/xBi4.5K0.5Ti4O15 composites (x = 0–0.4) have been synthesized by solid state reaction method. Evolution of microstructure and electric properties has been investigated with varying composition ratio. X-ray diffraction, Raman and IR absorption confirm the crystal transition tendency from orthorhombic to tetragonal phase. Evident texture along c-axis crystallographic orientation is observed in structure and morphology characteristics with x = 0.05 and 0.1. Through modulating the mole ratio of Bi4.5K0.5Ti4O15, coexistence of ferroelectric order and relaxor state is verified by the variation of ferroelectric hysteresis loops and polarization current density. This behavior can be attributed to the uncertain stability of discernable ferroelectric order induced by electric field among polar nanoregions during symmetry distoration. Temperature dependence of dielectric properties suggests an excellent thermal stability during a wide temperature range. Moreover, the detailed dielectric mechanism has been analyzed via various methods. Electrical conduction in grains and grain boundaries respectively plays the different role during the varying temperature process.