Growth,microstructure, energy–storage and dielectric performances of chemical–solution NBT–based thin films: Effect of sodium nonstoichimometry

Na_0.5+δBi_0.5(Ti_0.96W_0.01Ni_0.03)O₃ thin films with various Na contents (abbreviated as Na_.5+δBTWN, δ?=?? 3.0, ??1.5, 0, 1.5%) were fabricated on ITO/glass substrates using a chemical–solution process. The effects of Na nonstoichiometry on the microstructure, insulating, ferroelectric and dielectric performances are investigated. The pure perovskite phase can be obtained in Na_0.5BTWN and Na_0.515BTWN, while for Na_0.470BTWN or Na_0.485BTWN, the main composition contains secondary phase of TiO₂. The grain size increases from 30?nm at δ?=?? 3.0% to 55?nm at δ?=?0%, then decreases to 52?nm with δ?=?1.5%. The leakage current of Na_0.485BTWN sample is reduced dramatically in comparison with Na_0.5+δBTWN (δ?=?? 3.0, 0, 1.5%). The big recoverable energy–storage density of 63.1?J/cm² and high energy–storage efficiency of 55.0% can be obtained for Na_0.485BTWN due to the improved electric break–down strength and large difference value between the remanent polarization and maximum polarization. Enhanced dielectricity is achieved in Na_0.485BTWN with a high tunability of 36.0% and a figure of merit of 4.0 at 450?kV/cm and 500?kHz. These results demonstrated that the crystallization, micrographs and energy storage and dielectric properties of Na_0.5Bi_0.5TiO₃ are highly sensitive to low levels of Na–site nonstoichiometry.     

Effects of TiN addition on the properties of hot pressed TiN–Ti/Al2O3 composites

TiN–Ti/Al₂O₃ composites of varying TiN content (0–20?vol%) were prepared by vacuum hot-pressing sintering at different temperatures (1400?°C and 1500?°C) to investigate how TiN affected the mechanical properties and electrical conductivity of the composites. Sintered samples with added TiN exhibited better performance than those without it. The sample with 20?vol% TiN sintered 1500?°C had an optimal relative density of 99.49, Vickers hardness of 14.94?GPa, flexural strength of 321.55?MPa, and electrical resistivity of 1474.7?μΩ?cm. However, this increased temperature did not improve the best sample resistivity of 930.3?μΩ?cm, which was obtained at 1400?°C. Form SEM images and XRD patterns, the positive effect of TiN on composite mechanical properties may be ascribed to its good performance of high hardness and strength, a decrease of the brittle intermetallic phase, the form of AlTi₃N, and the impact of the fine-grained strength of the TiN phase.     

Advanced visible-light photocatalytic property of biologically structured carbon/ceria hybrid multilayer membranes prepared by bamboo leaves

Biologically structured carbon/cerium dioxide materials are synthesized by biological templates. The microscopic morphology, structure and the effects of different oxidation temperatures on materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) ultraviolet-visible light spectrum (UV–Vis) and X-ray Photoelectron Spectroscopy (XPS). Moreover, by splitting water under visible light irradiation, the hydrogen production is measured to test the photocatalytic property of these materials. The results show that materials made with bamboo biological templates which are immersed in 0.1 mol L^?1 of cerium nitrate solution, then carbonizated in nitrogen (700 °C) and oxidized in air (500–600 °C), can obtain the biological structure of bamboo leaves. The product is in the composition of hybrid multilayer membrane, which one is carbon membrane form plant cell carbonation and another is ceria membrane by nanoparticle self assembly. The best oxidation temperature is 550 °C and the band gap of carbon/cerium dioxide materials synthesized at this optimum oxidation temperature could be reduced to 2.75 eV. After exposure to visible light for 6 h, the optimal hydrogen production is about 302 μmol g^?1, which is much higher than that of pure CeO₂.     

转炉钢渣在西南某水泥厂的应用实例

随着新型干法旋窑水泥工艺的进步，在降本增效力度上，对废弃资源的再利用提出了进一步的要求。西南某水泥厂现有2 500 t/d新型干法水泥生产线一条，年产水泥90万t。主要生产P·O32.5和P·O42.5R水泥，产量分别占比为30%和70%，自2009年投产起，就开始应用转炉钢渣作为铁质校正料，并于2015年起将其用于水泥混合材中，使用量逐年增加并已稳定应用。     

Power Generation from Coke Oven Gas Using Chemical Looping Combustion: Thermodynamic Simulation

A chemical looping combustion (CLC) combined cycle with coke oven gas as fuel and NiO/NiAl₂O₄ as an oxygen carrier is proposed. The system was simulated by Aspen Plus® and the oxygen carrier circulation ratio was calculated. The effects of key operational temperatures and different gas turbines on the system performance were investigated. Under optimized conditions, a high CO₂ capture efficiency could be achieved. To capture CO₂ thoroughly, the PG6561B gas turbine can be employed, allowing for nearly 100 % CO₂ capture efficiency.     

Supramolecular Chiral Aggregates Exhibiting Nonlinear CD–ee Dependence

Although a linear relationship between the optical activity (normally the CD signal) and the enantiomeric excess (ee) of chiral auxiliaries has been the most commonly observed dependence in dynamic supramolecular helical aggregates, positive nonlinear CD–ee dependence, known as the “majority-rules effect” (MRE), indicative of chiral amplification, has also been well documented and to some extent understood. In sharp contrast, the negative nonlinear CD–ee dependence has been much less reported and is not well understood. Here, the state of the art of both the positive and negative nonlinear CD–ee dependence in noncovalently bound supramolecular helical aggregates is summarized, with the hope that the vast examples of supramolecular aggregates showing positive nonlinear dependence, in terms of the methods of investigations, variations in the structure of the building block (single species or multiple species), and theoretical modeling using the mismatch penalty energy and helix reversal penalty energy, would help to guide the design of building blocks to form aggregates showing negative nonlinear dependence, and thus to understand the mechanisms. The potential applications of those functional supramolecular aggregates are also discussed.     

基于MOFs在体育场顶棚用新材料氨基功能化的应用

针对体育场用顶棚用材质,因其所处环境恶劣复杂,常年风吹日晒以及高强度的冲击性能,对材质的韧性及强度要求极高,本文以金属有机骨架材料作为平台,设计合成了氨基功能化的Cu3(BTC)2,并对合成的材料进行XRD表征分析、FT-IR表征、材料形貌和结构表征、孔径结构的表征,最后以苯甲醛和氰基乙酸乙酯的缩合反应作为反应底物,考察了合成材料以碱为催化剂的催化反应能力。结果,多次碱催化反应后,材料的结构发生了变化,材料性能得到优化。     

Atomic Modulation Triggering Improved Performance of MoO3 Nanobelts for Fiber‐Shaped Supercapacitors

Asymmetric supercapacitors (ASCs) are emerging as a new class of energy storage devices that could potentially meet the increasing power and energy demand for next‐generation portable and flexible electronics. Yet, the energy density of ASC is severely limited by the low capacitance of the anode side, which commonly uses the carbon‐based nanomaterials. Here, the demonstration of sulfur‐doped MoO_3?x nanobelts (denoted as S‐MoO_3?x) as the anode for high‐performance fiber‐shaped ASC are reported. The Mo sites in MoO₃ are intentionally modulated at the atomic level through sulfur doping, where sulfur could be introduced into the MoO₆ octahedron to intrinsically tune the covalency character of bonds around Mo sites and thus boost the charge storage kinetics of S‐MoO_3?x. Moreover, the oxygen defects are occurring along with sulfur‐doping in MoO₃, enabling efficient electron transport. As expected, the fiber‐shaped S‐MoO_3?x achieves outstanding capacitance with good rate capability and long cycling life. More impressively, the fiber‐shaped ASC based on S‐MoO_3?x anode delivers extremely high volumetric capacitance of 6.19 F cm^?3 at 0.5 mA cm^?1, which makes it promising as one of the most attractive candidates of anode materials for high‐performance fiber‐shaped ASCs.