(1-x)Bi0.5Na0.47Li0.03TiO3-xNaNbO3 lead-free ceramics with superior energy storage performances and good temperature stability

Dielectric capacitors show great potential in superior energy storage devices. However, the energy density of these capacitors is still inadequate to meet the requirement of energy storage applications. In this study, the Bi_0.5Na_0.47Li_0.03TiO₃-xNaNbO₃ (BNLT-xNN) ceramics were prepared via conventional solid-phase reaction. Results showed that NN can efficaciously enhance the breakdown strength (E_b) and the relaxation behavior of the BNLT ceramic because of the broken ferroelectric long-range order. When x = 0.3, the maximum E_b reached 350 kV/cm, at which the 0.7BNLT-0.3NN ceramic exhibited the high recoverable energy storage density (W_rec) of 4.83 J/cm³ and great efficiency (η) of 78.9%. The ceramic demonstrated good temperature stability at 20 °C-160 °C and excellent fatigue resistance. Additionally, the 0.7BNLT-0.3NN ceramic presented high power density (P_D; ～77.58 MW/cm³), large current density (C_D; ～861.99 A/cm²), and quite short discharge time (t_0.9; ～0.090 μs). These results indicated that the 0.7BNLT-0.3NN material has excellent energy storage properties and various application prospects.     

Large electrostrictive effect and high energy storage performance of Pr3+-doped PIN-PMN-PT multifunctional ceramics in the ergodic relaxor phase

The photoluminescence, dielectric relaxation, ferroelectric hysteresis, and field-induced strain properties of Pr³⁺-doped 0.24Pb(In_1/2Nb_1/2)O₃-0.42Pb(Mg_1/3Nb_2/3)O₃-0.34PbTiO₃ (PIN-PMN-PT:Pr³⁺) multifunctional ceramics have been investigated. It was found that Pr³⁺ doping enhanced the dielectric diffuseness and relaxation behavior of PIN-PMN-PT ceramics. Slim P-E loops and S-E curves appear in PIN-PMN-PT:Pr³⁺ ceramics when the Pr³⁺ doping concentration reaches 1.4 mol%. Local domain configurations associated with phase transitions were investigated by piezoresponse force microscopy (PFM). Large electrostrictive coefficient Q₃₃ (?0.03 m⁴/C²) and high energy-storage efficiency η (92%) were obtained in 2 mol% Pr³⁺-doped PIN-PMN-PT ceramic in the ergodic relaxor (ER) phase at room temperature. The giant electrostrictive effect and excellent energy-storage performance are related to the field-induced dynamic behavior of polar nanoregions (PNRs). The results show that the PIN-PMN-PT:Pr³⁺ system is an excellent multifunctional material for making electromechanical and energy storage devices.     

Novel core-shell-like Ni-supported hierarchical beta zeolite catalysts on bioethanol steam reforming

Hierarchical-Beta zeolites have been hydrothermally synthesized by adding a new gemini organic surfactant. The used gemini surfactant play the role of a “pore-forming agents” on the mesoscale, on the same time, providing alkaline environment for the system. With this hierarchical Beta zeolite as the core support, we successfully prepared a shell layer of Ni-containing (22 wt%) petal-like core-shell-like catalyst and applied it to bioethanol steam reforming. At the reaction temperature of 350 °C–550 °C, the conversion rate of ethanol and the selectivity of hydrogen were always above 85% and 70%. After reaction of 100 h on stream at 400 °C, there were not obvious inactivation could be observed on NiNPs/OH-MBeta catalyst.     

Photocatalytic hydrogen generation by WO3 in synergism with hematite-anatase heterojunction

The present study reports about exploration of a multi-component photocatalytic system comprising of WO₃, TiO₂ and Fe₂O₃ with tandem n-n heterojunctions. The ternary WO₃/TiO₂/Fe₂O₃ nanocomposite with WO₃ nanoparticles over the interfaces of Fe₂O₃ and TiO₂ is synthesized by wet precipitation followed by thermal decomposition. The WO₃/TiO₂/Fe₂O₃ nanocomposite has an enhanced photocatalytic performance towards hydrogen generation by water splitting reaction under visible light irradiation, when compared to the Fe₂O₃/TiO₂ system. A band gap of 2.10 eV, favouring visible light absorption was achieved with the distribution of WO₃ nanopartcles over the interfaces of Fe₂O₃ and TiO_2. The as prepared WTF heterojunction exhibited a maximum hydrogen production rate of 10.2 mL h⁻¹ for a catalyst loading of 0.025 g mL⁻¹. The enhanced photocatalytic performance is tested in presence of various sacrificial agents and proton source. In both cases, the higher photocatalytic efficiency is attributed to the more visible light harnessing ability and pronounced charge separation owing to the tandem n-n heterojunctions generated between TiO₂ with WO₃ and TiO₂ with Fe₂O₃ semiconductors and enhancing the lifetime of the photogenerated electron-hole pairs.     

Investigation on elemental mercury removal by cerium modified semi-coke

Coal-fired power plant is the largest anthropogenic mercury source. Active carbon injection technique has been widely used to control the mercury emissions. However, high operation cost limits its development and it is necessary to find other potential mercury sorbents. In this study, raw semi-coke and a series of novel cerium (Ce) modified semi-cokes were synthesized and utilized for removing elemental mercury (Hg⁰) from simulated flue gas. It is noteworthy that the efficiencies were tested without hydrogen chloride (HCl) in order to evaluate the sorbents efficacy for low-chlorine (Cl) coal. The results show that the modified sorbents exhibited the best performance at 150 °C. The performance of sorbent could be reinforced due to the existence of oxygen (O₂), nitric oxide (NO) and HCl. The adverse effect caused by sulfur dioxide (SO₂) reduced dramatically after Ce modification. The negative impact of ammonia (NH₃) on Hg⁰ removal in this study could be neglected owing to the tiny concentration of NH₃. Raw semi-coke provided sufficient carbon content, which is favorable to mercury adsorption. As Ce loading increased, the carbon structure changed and the crystal of cerium oxide was formed in the modified semi-coke. The mass fraction of cerium oxide on the sorbent was over 4.4% when the concentration of Ce modification solution was higher than 0.2 mol L⁻¹. The redox reaction activity and the oxygen storage ability of Ce³⁺/Ce⁴⁺ gave a huge boost to the performance of modified semi-coke. The addition of Ce also had an impact on the proportion of oxygen species.     

A design of a robust discrete-time controller

In this paper, we proposed a robust discrete-time controller. This control system, which is derived from the idea of the normalized plant, does not include plant parameters. Thus, we obtain a control system independent of plant parameters and that has the same structure as a conventional optimal servo control system. Simulation and experimental results show that the proposed method is fairly robust to plant parameter variations and external disturbances.     

Dandelion-Like Bi2S3/rGO hierarchical microspheres as high-performance anodes for potassium-ion and half/full sodium-ion batteries

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as attractive alternatives for next-generation battery systems, which have promising application potential due to their earth abundance of potassium and sodium, high capacity and suitable working potential, however, the design and application of bi-functional high-performance anode still remain a great challenge up to date. Bismuth sulfide is suitable as anode owing to its unique laminar structure with relatively large interlayer distance to accommodate larger radius ions, high theoretical capacity and high volumetric capacity etc. In this study, dandelion-like Bi₂S₃/rGO hierarchical microspheres as anode material for PIBs displayed reversible capacity, and 206.91 mAh·g⁻¹ could be remained after 1,200 cycles at a current density of 100 mA·g⁻¹. When applied as anode materials for SIBs, 300 mAh·g⁻¹ could be retained after 300 cycles at 2 A·g⁻¹ and its initial Coulombic efficiency is as high as 97.43%. Even at high current density of 10 A·g⁻¹, 120.3 mAh·g⁻¹ could be preserved after 3,400 cycles. The Na₃V₂(PO₄)₃@rGO//Bi₂S₃/rGO sodium ion full cells were successfully assembled which displays stable performance after 60 cycles at 100 mA·g⁻¹. The above results demonstrate that Bi₂S₃/rGO has application potential as high performance bi-functional anode for PIBs and SIBs.

     

High energy storage properties of lead-free Mn-doped (1-x)AgNbO3-xBi0.5Na0.5TiO3 antiferroelectric ceramics

In this work, 0.2 wt.% Mn-doped (1-x)AgNbO₃-xBi_0.5Na_0.5TiO₃ (x = 0.00–0.04) ceramics were synthesized via solid state reaction method in flowing oxygen. The evolution of microstructure, phase transition and energy storage properties were investigated to evaluate the potential as high energy storage capacitors. Relaxor ferroelectric Bi_0.5Na_0.5TiO₃ was introduced to stabilize the antiferroelectric state through modulating the M₁-M₂ phase transition. Enhanced energy storage performance was achieved for the 3 mol% Bi_0.5Na_0.5TiO₃ doped AgNbO₃ ceramic with high recoverable energy density of 3.4 J/cm³ and energy efficiency of 62% under an applied field of 220 kV/cm. The improved energy storage performance can be attributed to the stabilized antiferroelectricity and decreased electrical hysteresis ΔE. In addition, the ceramics also displayed excellent thermal stability with low energy density variation (<6%) over a wide temperature range of 20−80 °C. These results indicate that Mn-doped (1-x)AgNbO₃-xBi_0.5Na_0.5TiO₃ ceramics are highly efficient lead-free antiferroelectric materials for potential application in high energy storage capacitors.     

Simulation optimization approach for hybrid flow shop scheduling problem in semiconductor back-end manufacturing

This study presents a simulation optimization approach for a hybrid flow shop scheduling problem in a real-world semiconductor back-end assembly facility. The complexity of the problem is determined based on demand and supply characteristics. Demand varies with orders characterized by different quantities, product types, and release times. Supply varies with the number of flexible manufacturing routes but is constrained in a multi-line/multi-stage production system that contains certain types and numbers of identical and unrelated parallel machines. An order is typically split into separate jobs for parallel processing and subsequently merged for completion to reduce flow time. Split jobs that apply the same qualified machine type per order are compiled for quality and traceability. The objective is to achieve the feasible minimal flow time by determining the optimal assignment of the production line and machine type at each stage for each order. A simulation optimization approach is adopted due to the complex and stochastic nature of the problem. The approach includes a simulation model for performance evaluation, an optimization strategy with application of a genetic algorithm, and an acceleration technique via an optimal computing budget allocation. Furthermore, scenario analyses of the different levels of demand, product mix, and lot sizing are performed to reveal the advantage of simulation. This study demonstrates the value of the simulation optimization approach for practical applications and provides directions for future research on the stochastic hybrid flow shop scheduling problem.     

A lanthanide azametallacrown with aza10-MC − 4 motif: Structure and single molecule magnetism behavior

A rare lanthanide-containing azametallacrown with structural formula [Er₄(μ₃-OH)₂(ppt)₄(H₂ppt)₂(OAc)₂]·2DMF (1) (H₂ppt = 3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole) has been reported. X-ray crystallographic analysis exhibits a remarkable aza10-MC-4 structural motif with the ring having [Er–N–N–Er–O] connectivity. Measurements of dc magnetic susceptibility and isothermal magnetization reveal the strong magnetic anisotropy, and ac susceptibility shows slow magnetization relaxation at a dc field of 2000 Oe.