加强型Bi-2212超导股线有限元拉伸性能分析

为探究加强型Bi-2212超导股线的力学性能以及不锈钢包带对超导股线力学性能的影响，运用Ansys软件建立加强型Bi-2212超导股线的三维模型，采用有限元分析方法，对其机械结构进行仿真，模拟高温高压热处理后轴向受拉形变量和应力应变分布情况。仿真结果显示，在同样施加100 N拉力的情况下，与超导原线（Bi-2212超导线）相比，密绕Ni₈₀Cr₂₀包带后的加强型Bi-2212超导股线轴向受拉形变程度减小，约10%;应力应变均降低，约30%。采用Ni₈₀Cr₂₀作为外包带制成的加强型Bi-2212超导股线力学性能显著，是未来超导线发展方向之一。     

胍基硅前驱体的合成及应用

以胍基取代的二甲基二氯硅烷与胺基锂反应合成了3种硅基化合物,使用核磁共振、高分辨质谱、元素分析对化合物结构进行了表征,通过热重分析(TGA)研究了化合物的热稳定性、挥发性、蒸汽压等性能。 3种化合物均具有良好的热稳定性及挥发性,无明显热分解过程,固体残留小于1%,接近纯挥发过程,最高蒸汽压在3600~5300 Pa,满足前驱体使用要求。 以二甲基-胍基-甲乙胺基-硅烷为前驱体,采用螺旋波等离子体气相沉积(HWPCVD)工艺制备了硅基薄膜,使用X射线光电子能谱(XPS)和扫描电子显微镜(SEM)分析了薄膜的化学组成和膜表面结构,XPS分析结果证实该薄膜为Si、N、C组成,实验结果表明,该类胍基硅化合物可作为硅基化学气相沉积(CVD)前驱体材料应用于集成电路制造。     

A Photoactivated Cu–CeO2 Catalyst with Cu-[O]-Ce Active Species Designed through MOF Crystal Engineering

Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper–ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion.     

A self-penetrating and chemically stable zinc (ii)-organic framework as multi-responsive chemo-sensor to detect pesticide and antibiotics in water

Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)_0.5(bimb)]·H₂O}_n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {8⁶} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium.     

Space-Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium-Ion Batteries

Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.     

Synthesis,characterization, and thermal properties of novel silicon 1,1,3,3-tetramethylguanidinate derivatives and use as single-source chemical vapor deposition precursors

A series of chemical vapor deposition (CVD) precursors have been synthesized by a single-step reaction of 1,1,3,3-tetramethylguanidine and a variety of silicon chlorides. The structures of the 1,1,3,3-tetramethylguanidinate-based compounds were verified by ¹H NMR, ¹³C NMR, XPS, EI-MS, and elemental analysis. The thermal stability, transport behavior, and vapor pressures of these compounds were evaluated by simultaneous thermal analyses (STA). These compounds are highly stable and those in liquid form are very volatile. Silicon carbonitride (SiCN) thin films were prepared by using bis (tetramethylguanidine)-dimethyl-silane as the precursor in helicon wave plasma chemical vapor deposition (HWP-CVD). The properties of the films were investigated by SEM, AFM, and XPS. The results showed that the films have good uniformities, low friction coefficient, and high hardness, enabling the films for fabrication of semiconductor devices.     

A Niobium Oxyiodate Sulfate with a Strong Second‐Harmonic‐Generation Response Built by Rational Multi‐Component Design

A novel niobium oxyiodate sulfate, Nb₂O₃(IO₃)₂ (SO₄), was fabricated by a rational multi‐component design under moderate hydrothermal conditions. This multi‐component design is inspired by an interesting niobium oxysulfate reaction, which opens a new door for synthetic method to effectively introduce refractory metals such as Nb into crystal structures by hydrothermal synthesis. Nb₂O₃(IO₃)₂(SO₄) features a cube‐like topological structure with a large phase‐matching second harmonic generation (SHG) response (6×KDP), a wide transparency window (0.38–8 μm), and a high laser damage threshold (LDT) (20×AgGaS₂). It has the highest thermostability (stable up to 580 °C under air) among reported non‐centrosymmetric (NCS) iodates and sulfates and is stable in water and even concentrated H₂SO₄. Furthermore, Nb₂O₃(IO₃)₂(SO₄) is a unique nonlinear optical (NLO) material among iodates and sulfates, because its SHG effect is mainly caused by the MO₆ units rather than the IO₃ or SO₄ units, which is demonstrated by density functional theory (DFT) calculations.     

A Semiconducting Organic–Inorganic Hybrid Perovskite‐type Non‐ferroelectric Piezoelectric with Excellent Piezoelectricity

Piezoelectric materials are a class of important functional materials applied in high‐voltage sources, sensors, vibration reducers, actuators, motors, and so on. Herein, [(CH₃)₃S]₃[Bi₂Br₉]( 1 ) is a brilliant semiconducting organic–inorganic hybrid perovskite‐type non‐ferroelectric piezoelectric with excellent piezoelectricity. Strikingly, the value of the piezoelectric coefficient d₃₃ is estimated as ≈18 pC N^?1. Such a large piezoelectric coefficient in non‐ferroelectric piezoelectric has been scarcely reported and is comparable with those of typically one‐composition non‐ferroelectric piezoelectrics such as ZnO (3pC N^?1) and much greater than those of most known typical materials. In addition, 1 exhibits semiconducting behavior with an optical band gap of ≈2.58 eV that is lower than the reported value of 3.37 eV for ZnO. This discovery opens a new avenue to exploit molecular non‐ferroelectric piezoelectric and should stimulate further exploration of non‐ferroelectric piezoelectric due to their high stability and low loss characteristics.