查看更多>>摘要：An approach to decrease the core (iron) loss of grain-oriented silicon steel sheets is to reduce the magnetic domain size by using laser irradiation on the surface of the sheets. In this research, after finding the optimal conditions for traditional laser scribing of HIB (high-permeability)-steel sheets, the effect of the two new parameters “two-sided laser-scribing” and “simultaneous application of magnetic field during laser-radiation” on reducing core losses was investigated. By optimizing the variables in the traditional method (laser scribing on one side without the presence of magnetic fields), core losses at 1.7 T and 50 Hz were reduced by 9.7%. Laser treatment of both sides resulted in a decrease of core loss of 13.7%. Applying a magnetic field during laser scribing could have a positive or negative effect on core losses, depending on the direction of the magnetic field. In the optimum conditions, with double-sided laser scribing of HIB-sheets in the presence of a magnetic field, core losses were reduced by 16.8%. This is a significant result compared to the 9.7% of the traditional method.
查看更多>>摘要：Photocatalytic overall water splitting is considered as one of the most promising way to solve the energy crisis. Herein, Pt/g-C3N4/BiOBr S-scheme heterojunction photocatalyst with hollow microsphere structure was prepared by solvothermal method, and its photocatalytic activity toward overall water splitting was evaluated. The H2 evolution rate of Pt/g-C3N4/BiOBr is 361 μmol·g?1·h?1, which is 2.7 times higher than that of g-C3N4. Furthermore, it is noteworthy that the overall water splitting occurred through the two-electron pathway. S-scheme heterojunction, hollow structures and surface plasmonic resonance of Pt are combined in one photocatalyst system. This study provides a new way for the development of high efficiency H2 evolution photocatalyst.
查看更多>>摘要：ZnO samples were prepared by an easy process based on green synthesis using three different concentrations of the parsley extract as natural reducing agents. The semiconductors were characterized structural, morphological, and opto-electronically by XRD, SEM-EDS, diffuse reflectance, and photo-response, respectively. Hexagonal structure ZnO-based semiconductors were obtained after the annealing process at 400oC. The morphology, bandgap, and photo-response of the synthesized samples were sensitive to the extract concentrations used in this work. The incorporation of Mg traces in the bulk of ZnO produced changes in the c-lattice parameter, consequently forming native defects such as Oi and Vo. The bandgap increased as the Mg content in the ZnO increased too. The photo-response analysis suggested that the samples with 0.44 and 1.33 at% of Mg were p-type ZnO, while the sample with 2.01 at% was n-type ZnO. It likely means that the conductivity type and other optoelectronic characteristics depend on the Mg content in the ZnO samples and the formation of predominant native defects due to the interaction of Mg with the crystalline structure.
查看更多>>摘要：Materials: in which ferroelectric polarization can be locally controlled have potential for high-density information storage applications. Herein, we investigated the ferroelectric polarization switching characteristics of epitaxial BaTiO3/PbTiO3 (BTO/PTO) multilayer thin films by using piezoresponse force microscopy. Pulsed laser deposition was used to form an epitaxial BTO layer on an epitaxial ferroelectric PTO single thin film. This epitaxial BTO/PTO multilayer thin film exhibited an imprint phenomenon, in which the internal electric field was asymmetrically induced and the ferroelectric hysteresis loop was shifted. Owing to this imprint phenomenon, a large difference occurred between the two coercive electric fields of the ferroelectric hysteresis loop. Because the coercive electric field was reduced in one direction, a relatively small switching voltage was required to form ferroelectric polarization nanobits in a local region and the size of the switched nanobits was minimized. This behavior can be utilized as the basis for developing high-density ferroelectric-based storage media.
查看更多>>摘要：Photocatalysis is a sustainable energy conversion technology for degradation of organic pollutants, while developing high-performance photocatalysts is a major task of photocatalysis. Herein, potassium citrate-derived carbon nanosheets (Cs) are prepared and acted as sacrificial templates for preparing Cs/MnO2 nanosheets arrays, and then thin BiOCl nanosheets are deposited to fabricate Cs/MnO2/BiOCl (Cs/Mn/Bi) composite photocatalyst. Through adjusting the loading amount of BiOCl, the optimized Cs/Mn/Bi-1/1 composite exhibits the highest photocatalytic activity and excellent recycling degradation performance, which degrades 97% of Rhodamine B in 25 min, 98% of Methylene blue in 40 min, and 80% of Tetracycline hydrochloride in 30 min, and the degradation rate constant is 0.129, 0.081 and 0.038 min?1, respectively. Based on electron spin resonance result, ·O2? and ·OH radicals are the reactive species for degradation of organic pollutants, and the photocatalytic mechanism is verified as the Z-scheme transfer mode. The superior photocatalytic performance is attributed to the formation of Z-scheme heterojunction between MnO2 and BiOCl, which narrows the band gap and broadens the light absorption range. Furthermore, conductive carbon layer in composite reduces the charge transfer resistance and accelerates the separation and transfer efficiency of photogenerated carriers.
查看更多>>摘要：Due to its unique I-V property, memristor is considered to be the key device for artificial intelligence application. Among the alternative memristor materials, organometal trihalide perovskite (OTP) follow with interest in photoelectric coupling area with excellent light absorption ability. However, the power consumption of OTP memristor still remains to be reduced. Here, Cs0.05(FAxMA1?x)0.95PbIyBr3?y (CsFAMAPbIBr) with prominent photoresponse property is used as the functional layer of the memristor. Maximum high resistance state (HRS)/low resistance state (LRS) (~100) and maximum power of 9.8 × 10?9 W is reached under small voltage (?1 V~1 V) with W/OTP/Al structure. Since the oxide modification layer acts as a series resistance for the device, when 90 nm thickness of zinc oxide layer is added to the W/OTP interface, the power consumption of the device is reduced by an order of magnitude. Then, the maximum power of the device decreases by two orders of magnitude (to 2.5 × 10?11 W) under 2 mW/cm2 light condition, and the phenomenon called negative photoconductance (NPC) effect that defined as an increase in resistance upon exposure to illumination. Through the optical and oxide modification, OTP memristor with low power consumption is achieved.
查看更多>>摘要：In the present paper, polycrystalline samples of LiInCr4-xMnxO8 varying from 0.0 to 0.5 were synthesized by the solid state method. In order to explore the effect of substitution Cr by Mn in LiInCr4O8, the structural, magnetic and dielectric properties are studied. The result of XRD patterns show that there is a nonmonotonic expansion in the lattice parameter, which may be due to ions disorder or/and partial exchange between A- and B-atoms. The SEM micrographs show that the Mn substituted samples are smaller in the average crystallite size and more agglomerated than the parent material. Magnetization data show the nonmonotonic variation of the effective magnetic moment and Curie-Weiss temperature, the suppressed long-range antiferromagnetic (AFM) order and spin gap, and occurrence of a spin glasslike state. Although the breathing pyrochlore lattice is robust against doping, only 5% doping concentration (x = 0.2) makes the spin gap vanish absolutely. The increased Bf makes the pyrochlore lattice more uniform, leading to the disappearance of the spin gap. The dielectric data show that Mn doping increases the dielectric constant and decreases dielectric loss at room temperature, thus these compounds should be satisfactory to the possible application in microelectronics. The result of heat capacity also verifies glass-type insulator state.
查看更多>>摘要：We investigate the piezoelectric and ferroelectric properties in island-like ferroelectric regions of bismuth ferrite oxide films. Samples were synthesized by the simultaneous laser ablation of bismuth, and iron oxide targets. Bismuth content in the deposited films was controlled with the plasma density (Np) that is produced during the ablation of the Bi target. A change in the NpBi alters the Bi incorporation into the films. Relatively homogeneous films deposited at NpBi of 11 × 1012 cm?3 with an effective piezoelectric coefficient (deff) of ~15 pm/V served as the starting point. A reduction of NpBi at 2 × 1012 cm?3 produced films with almost null piezoelectrical response but at 4 × 1012 cm?3 caused the formation of island-like ferroelectric regions with large deff values that spans from 70 to 108 pm/V. The island-like regions presented upright hysteretic phase-switching loops with low coercive voltages and squareness values close to unity. The resulting large deff values were attributed to the reduction of the substrate-clamping effect, the (001)-textured BiFeO3 structure, and the coexistence of secondary phases with the main BiFeO3 phase. The mechanisms for polarization switching and the electromechanical response of the island-like regions are discussed. Finally, some preliminary results of ferroelectric fatigue experiments in island-like regions are presented.
查看更多>>摘要：The high-temperature deformation mechanical behavior and dynamic recrystallization(DRX) kinetics model of Ti-47.5Al-2.5 V-1.0Cr-0.2Zr alloy were studied by thermal compression tests on a Gleeble thermal simulator. The influences of deformation heat and friction on rheologic stress were calculated and corrected. The results show that the rheologic stress corrected by friction is less than the experimental stress value. This shows that the existence of interface friction has a negative effect on stress. The influence of deformation heat on the stress is significant at lower temperatures and higher strain rates. The stress-strain curve shows the peak stress at low strain, and then descends with increasing of strain. Based on the curve of the work hardening rate versus stress (dσ?dε versus σ) the characteristic strain of the alloy was determined, containing the critical strain of DRX and peak strain, and the expression between the critical stress of DRX, the peak stress and the Z parameters was established. To describe the variation law of the DRX volume fraction, DRX kinetics were examined. The Avrami index values of the alloy were all less than 2 within the parameters of this experiment. The smaller Avrami index of this alloy indicates that the recrystallization rate is lower than that of ordinary alloy. The fraction of DRX rises with increasing of strain. That is, the higher the thermal deformation strain is, the higher the external input energy and the greater the degree of DRX. At the same strain rate, the peak value of the DRX growth rate increases with the increasing of temperature, which reflects the effect of the thermal activation energy on the DRX dynamics.
查看更多>>摘要：Mechanical properties of fine-grained Al-(1, 2, 3)%Zn alloys obtained by Equal Channel Angle Pressing were studied. The recrystallization activation energy was found to decrease with increasing Zn content. The Hall-Petch coefficient for the Al-Zn alloys was found to change nonmonotonously during annealing. An increased Zn concentration at the grain boundaries was shown to result in altering the creep and superplasticity mechanisms of the Al-Zn alloys. The corrosion rate of the Al-Zn alloys was found to depend on the annealing temperature nonmonotonously. The corrosion rate in the Al-(2,3)%Zn alloy was shown to decreasing down to 8–9 mm/year with increasing the annealing temperature up to 200 оC. The increasing of the annealing temperature up to 300 оC leads to the increasing of the corrosion rate up to 11.4–11.9 mm/year. The obtained results were analyzed on the base of a concept of solid phase wetting of the grain boundaries in the Al by Zn. The effect of solid state wetting of the grains boundaries was shown to allow explaining majority of anomalia observed in the Al-Zn alloys: (i) the effect of the reduction of the recrystallization activation energy; (ii) the effect of a non-monotonous variation of the Hall-Petch coefficient during annealing; (iii) an increasing of plasticity of the Al-Zn alloys in the creep regime, etc. In order to describe the anomalia in the corrosion resistance of the Al-Zn alloys, one should also take into account a nonuniform Zn distribution in the specimens.
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Elsevier