Stereo-Active Lone Pairs Induced Giant Polarization in a 2D Ge-Based Halide Perovskite Antiferroelectric

Antiferroelectrics, characterized by electrically controlled antipolar-polar phase transformation, have attracted tremendous attention as a class of promising electroactive materials for assembling electronic devices. The emerging two-dimensional (2D) halide perovskites with superior compositional diversity offer an ideal platform for exploring electroactive materials, whereas lead-free antiferroelectric counterparts are still scarcely reported. Herein, for the first time, a new lead-free 2D germanium iodide perovskite antiferroelectric (i-BA)₂CsGe₂I₇ ( 1 , i-BA is iso-butylammonium) has been presented, which exhibits a high Curie temperature (T_c) up to 403 K. Remarkably, benefiting from the lone pair stereochemical activity in Ge²⁺ induced large structural distortion and Cs⁺ ion off-center displacement, 1 shows well-defined double P–E hysteresis loops in a wide temperature range with a giant maximum polarization up to 18.8 µC cm⁻², which achieves a new high record among molecular antiferroelectrics. Moreover, under a low external electric field of 22.5 kV cm⁻¹, the antipolar-polar phase transformation in 1 affords a recoverable energy storage density W_rec of 0.27 J cm⁻³ and high storage efficiency up to 79.76%. Such lead-free halide perovskite antiferroelectric with intriguing antiferroelectric behaviors, including high T_c, large polarization and remarkable energy storage properties, is exciting, which provides an alternative candidate for high-performance antiferroelectrics for environmentally friendly electronic devices.     

巨磁阻抗传感器应用研究最新进展

利用零磁致伸缩非晶丝的巨磁阻抗(GMI)效应,可制得新一类灵敏度高、响应快、功耗低、体积小的微型磁电式传感器。介绍了目前几种基于巨磁阻抗效应的传感器,包括磁场传感器、扭矩传感器、汽车交通监测系统和生物传感器等的工作原理和特性。     

西西伯利亚巨型含油气盆地中生界有机质的破坏因素

西西伯利亚巨型含油气盆地侏罗系有机质的成熟度取决于地层的埋深和这一时期它所经受的最高温度。沉积盖层中的温度分布与古生代基底局部断块的褶皱时代、深大断裂的形成时间，以及岩浆岩的成分、侵入时间有关。这些控制着温度场和西西伯利亚沉积盖层中有机质成熟度的因素是全球性的。划分出了3种基本的断块类型，它们与根据基底固结时代而划分的构造区划相对应。第1类断块与贝加尔褶皱带的断块相一致；第2类断块与海西运动期、加里东运动期的断块相一致；第3类断块为巨型盆地基底中的三叠纪裂谷，大型花岗岩体、某些流体输导断裂与此相一致。     

用于高灵敏微磁传感器的LMO膜制备与分析

采用溶胶凝胶法制备了LaMnOx(LMO)薄膜,系统研究了不同烧结温度、纵向直流磁场后退火和生长膜层数对LMO薄膜的巨磁阻抗效应的影响。结果表明,烧结温度、膜的层数以及纵向磁场后退火处理均有效提高了LMO的巨磁阻抗比,其中纵向直流磁场后退火处理提高薄膜阻抗比效果最显著,经过10Oe、400℃恒温1h磁场后退火处理后,在频率5MHz、100Oe外磁场下其磁阻抗比达15.8%,相比未后处理样品磁阻抗比提高了一倍,其对应的磁场灵敏度为0.16%/Oe。同时,实验发现磁场后退火不仅影响薄膜的巨磁阻抗比,也会改变阻抗比极大值所对应的激励频率,这一现象目前仍在探究中。     

Face colorings and chiral face colorings of icosahedral giant fullerenes: C80 to C240

Abstract

Combinatorial techniques based on Sheehan’s modification of P?lya’s theorem and M?bius inversion technique together with character cycle indices are applied to face colorings of giant fullerenes. These techniques are applied to icosahedral fullerenes, C₈₀ with a chamfered dodecahedron structure, a chiral fullerene C₁₄₀, icosahedral C₁₈₀ and C₂₄₀ with a chamfered truncated icosahedron geometry. The techniques are shown to provide both achiral and chiral face colorings of giant fullerenes for (a) coloring only pentagons with all hexagons painted white, (b) coloring hexagonal faces with all pentagons kept white, (c) both pentagons and hexagons painted with variable colors from a single set, and (d) both pentagons and hexagons painted with variable colors but chosen from two different sets. We have shown that in order to produce chiral colorings for the I_h fullerenes at least 2 black colors and remaining being white are needed when both pentagons and hexagons are varied. Results provide new insights into facial labeling and facial dynamics of fullerenes, while therefore being fully prepared to be inscribed in the new so called neutrosophical science (of carbon) nano-structural physical-chemistry.     

超磁致伸缩自感知执行器的理论与实验研究

对自感知的两种实现方法：电桥电路解耦与观测器解耦法,分别进行仿真并对观测器法进行实验验证。电桥电路仿真加入非线性模型,并对桥路输出信号进行放大滤波,为实验提供理论依据。观测器通过实验与观测计算对比验证了基于观测器自感知的可行性。     

What Happened to Ecology? John McHale and the Bucky Fuller Revival

Since the early 20th century, the environmental impulse in architecture has waxed and waned. Anthony Vidler considers this cyclical phenomenon, particularly in relation to the Independent Group in Britain during the 1950s, which culminated in John McHale's discovery of Richard Buckminster Fuller in 1955 and the full-blown Bucky Fuller revival of the 1960s. Copyright © 2010 John Wiley & Sons, Ltd.     

数字补偿式巨磁阻抗传感器设计

地磁环境下弱磁信号的检测要求地磁传感器具有灵敏度高、工作范围宽的特点,非晶丝在高频交流激励下具有阻抗变化率高的特点,宜于用来作地磁传感器.但非晶丝线性工作区较短,不能完全覆盖地磁场范围,通过采用数字补偿技术可以补偿大部分地磁场,使传感器工作于非晶丝的线性区,提高了传感器的灵敏度,扩展了传感器的工作范围.通过测试,采用数字补偿技术的巨磁阻传感器灵敏度为71. 133μV/nT,工作于-61 750. 8~73 774. 8 nT,与被测磁场的最大误差为2. 45 nT.     

一种基于阈值构建金融网络的新方法

针对复杂系统中构建网络的边相关系数阈值法,以金融网络为研究对象,改变以往的使用固定阈值的方法,提出根据相关系数矩阵和金融网络的内在属性确定阈值的新方法。基于股票的相关系数矩阵确定了网络的有效阈值区间,根据可以反映网络内在属性的最大连通子图的节点个数的变化情况来确定阈值,给出了构建金融网络的具体步骤。研究发现,利用该方法构建的金融网络拓扑结构显著。该方法可以推广应用到其他网络中。     

巨磁电阻效应的研究与应用

巨磁电阻效应位居当前凝聚态物理研究热点中的首位，因此得到了国内外研究人员的广泛重视。本文首先阐述巨磁电阻效应的作用机理及研究现状，进而对其应用进行综述，深人分析了几种巨磁电阻传感器的特性、工作原理、应用领域及存在问题，最后对巨磁电阻传感器的应用前景进行了展望。