Electro‐Mechanochemical Atom Transfer Radical Cyclizations using Piezoelectric BaTiO3

The formation and regeneration of active Cu^I species is a fundamental mechanistic step in copper‐catalyzed atom transfer radical cyclizations (ATRC). Typically, the presence of the catalytically active Cu^I species in the reaction mixture is secured by using high Cu^I catalyst loadings or the addition of complementary reducing agents. In this study it is demonstrated how the piezoelectric properties of barium titanate (BaTiO₃) can be harnessed by mechanical ball milling to induce electrical polarization in the strained piezomaterial. This strategy enables the conversion of mechanical energy into electrical energy, leading to the reduction of a Cu^II precatalyst into the active Cu^I species in copper‐catalyzed mechanochemical solvent‐free ATRC reactions.     

低成本硫化物固态电解质Li6-xPS5-xClx的制备与性能研究

硫化物固体电解质以其室温电导率高,热稳定性好,电化学窗口宽等特点,在高功率及室温固态电池方面优势突出,是极具潜力的固态电解质材料. 但制备其所需的高纯度Li₂S原料高昂的价格使其实际应用受到掣肘,故本文使用单质锂金属（99.9%）、升华硫、氯化锂和五硫化二磷等低成本原料,采用球磨法和高温热处理制备得到了Li_6-xPS_5-xCl_x（x = 0.5）固态电解质粉末,通过X射线衍射（XRD）、拉曼（Raman）、扫描电子显微镜（SEM）及能谱仪（EDS）对Li_6-xPS_5-xCl_x（x = 0.5）固态电解质进行了表征,并使用交流阻抗法测试了其电导率,电导率可达8.29×10 ^-4 S·cm ^-1,将Li_6-xPS_5-xCl_x（x = 0.5）固态电解质粉末进行冷压制片,制成Li对Li半电池后显示了良好的循环性能.     

红磷/石墨复合材料的制备及电化学性能

研究了一种先通过机械球磨和水热法制得的亚微米红磷,再通过球磨亚微米红磷与石墨得到的块状亚微米红磷/石墨复合材料(smRP/G),并利用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱分析(XPS)、循环伏安法(CV)等手段其进行了表征。 相对比普通红磷,亚微米红磷更容易通过球磨与石墨复合,能有效提升石墨材料的储锂容量。 为红磷在锂离子电池负极材料上的应用提供了一种思路。 在少量添加红磷的条件下,当红磷质量分数为3%时smRP/G表现最佳(3%smRP/G)。 在100 mA/g电流密度下展示出了1417 mA·h/g的首次放电容量,首次库伦效率67.4%。 并在循环200圈后依然保持着700 mA·h/g的可逆循环容量。     

球磨双金属氰催化剂催化CO_2/环氧丙烷/四氯苯酐三元共聚

由于共聚配合剂的加入有利于提高双金属氰催化剂(DMC)的催化活性,因此本文通过加入不同的共聚配合剂,采用绿色高效的机械球磨法制备了Zn-Co DMC催化剂体系,然后将DMC用于制备CO2、环氧丙烷和四氯苯酐(THPA)的三元共聚物聚碳酸亚丙酯四氯苯酐(PPCPA)。通过傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、多晶X射线衍射(XRD)、凝胶渗透色谱(GPC)和热重分析(TG)等技术手段表征了催化剂和PPCPA的结构和性能。结果表明,共聚配合剂辅助球磨Zn-Co DMC催化聚合反应转化数25.67~141.80,PPCPA数均相对分子量2.21×10~3~3.15×10~3,多分散指数1.04~1.24,呈现窄分布。PPCPA的热稳定性要高于聚碳酸亚丙酯(PPC),热分解温度提高了129.8℃。     

Mechanochemical Rhodium(III)‐ and Gold(I)‐Catalyzed C−H Bond Alkynylations of Indoles under Solventless Conditions in Mixer Mills

Mechanochemical activations in Rh^III‐ and Au^I‐catalyzed C?H alkynylations lead selectively to C₂‐ and C₃‐alkynylated indoles. The processes show excellent functional group tolerance, do not require additional heating and proceed under solventless conditions. Compared to solvent‐based standard protocols, the reaction times are shorter and the catalyst quantities lower resulting in high product yields under ambient atmosphere in mixer mills.     

A hybrid algorithm for the minimum bounding sphere problem

Two primal approaches, the shrinking approach and the dual approach, have been studied for the exact Minimum Bounding Sphere (MBS) problem. In this paper, we present a dual algorithm that uses the shrinking approach to solve subproblems. The experiments show our hybrid algorithm is faster than the dedicated shrinking algorithm and dual algorithm for solving the exact MBS problem in large point sets.     

Characterization of nanostructured ceramics prepared by both high energy ball milling and fast firing sintering processes

High-energy ball milling technique was successfully applied to calcinated lead zirconate titanate (PZT 60/40) powders. After 20?h of ball milling, large PZT particles were completely broken down, reducing its initial size in three orders of magnitude. Experimental results show a huge sinterability enhancement of the PZT powders by using this technique, achieving its maximum sintering rate at ～800°C. Relatively low densities (～91%) were achieved in stoichiometric samples, while in 3% lead excess samples sintered at 950°C for 30, 45, 60, 90 and 120?min using a fast firing process and a post-annealing treatment at 800°C for 4 h, densities of ～97% of the theoretical were achieved. PZT nanostructured ceramics prepared under optimized processing conditions (60?h of powder milling, 950°C of sintering temperature, 60?min of sintering time and a post-annealing process at 800°C during 4?h) show high dielectric constant (ε′) values (900) and low dielectric loss (tan?δ) at room temperature and a ferroelectric-paraelectric transition temperature at 375°C.     

The structure of nitrogen-supersaturated ferrite produced by ball milling

Highly supersaturated solid solutions of nitrogen in ferrite (bcc) were produced by ball milling of various powder mixtures of α-iron and ε-Fe₃N_1.08. The microstructure and the crystal structure of the product phases were examined as a function of nitrogen content using X-ray powder diffraction, high-resolution electron microscopy and Mössbauer spectroscopy. It was found that the grain size decreases with increasing nitrogen content. Unexpected shifts of the reflections in the X-ray powder diffraction patterns of the supersaturated N-ferrites, depending on the hkl values of the reflections and nitrogen content, were observed. These shifts cannot be explained by tetragonal distortion of the bcc unit cell, but they are in accordance with the occurrence of a certain type of stacking faults on bcc {211} planes. This result, together with the observation of some isolated fcc crystals (by high-resolution electron microscopy) and a drop in microstrain for high nitrogen contents, demonstrates that unconventional deformation mechanisms are operative in these materials below a certain grain size, leading to a breakdown of the classical Hall–Petch relation for mechanical strengthening.     

几个全纯函数空间上的乘子

设μ,ν是两个正规函数,本文刻划了Cn中单位球B上广义Bloch型空间βμ到βν以及一般函数空间F(p,q,s)到βν的点乘子.