关于钴基单分子磁体的研究进展

单分子磁体是涉及合成化学、材料科学和凝聚态物理等边缘学科的一个新颖课题。设计和合成具有特定结构和物理功能单分子磁体是近年来化学研究的一个热门方向。由于二价钴离子具有高达三个未成对电子,并且具有很大的单离子各项异性行为,因而成为构筑单分子磁体的一类重要金属离子。本文主要介绍了钴基单分子磁体的结构、制备方法、磁性、直流和交流磁化率、低温时不同振荡频率下的磁滞回线等几个方面,并对其发展前景进行了展望。     

具有分子双稳性的一维自由基磁相变材料的研究

具有分子双稳性的化合物是实现分子集合体作为新的光开关和信息存储元件的理想分子体系。本文合成苄基吡啶衍生物,研究其分子构象与堆积的关系,并研究了构建—维分子基磁体以及常温常压下的电学、磁学等性质。     

单分子磁体:基本概念与磁性表征

在分子磁体领域,一些多核或单核配合物呈现宏观磁体行为,这些配合物的磁性来源于孤立的分子内,因而吸引了许多化学家、物理学家和材料学家的研究兴趣,相继开展了这方面的研究.综述了近年来国内外相关研究进展,介绍了相关量子力学理论和一些具有代表性的实例,并进一步展望了今后的研究和发展方向.     

有机分子磁体的研究进展

在大量文献的基础上对有机分子磁体进行分类，从有机分子铁磁体、有机金属分子铁磁体和无机分子铁磁体三个方面介绍了有机分子磁体的最新研究进展。     

多维分子基铁磁体Co(phen)3[LiFe(ox)3]的合成与光谱表征

合成具有较高居里温度的分子基磁体材料和寻求高的相转变温度T c的分子基超导体一样,是当前分子材料领域中主要的研究方向.本文合成一种新的多维分子基铁磁体Co(phen)3[L iF e(ox)3],并用红外光谱表征其具有网络结构的配位聚合物。     

有机高分子磁体的分子设计

对有机高分子磁体的分子设计研究进行了综述,讨论了设计有机高分子磁体主要的4种理论模型,即Heiter London自旋交换模型、分子间电子转移模型、高自旋多重度模型和超级交换模型,并对这一领域的发展和应用进行了展望.     

单分子磁体与分子自旋电子材料

从单分子磁体合成、结构和性质及其在分子自旋晶体管、分子自旋电子管中的应用等方面,结合最新研究成果对这一有着应用前景的领域作了简要概述.单分子磁体是由内部的磁核和外围的有机分子壳层组成,可以通过修饰有机配体的基团和交换内部磁性离子等方法改善其物理和化学性能:带有烷基间隔基的[Co(Tpy-(CH2)5-SH)2]单核磁分子是一个弱偶合体系,而无烷基间隔基的[Co(TerPy)2]是强偶合,且Kondo温度异常地高(约25 K);将含两个磁中心的二核钒分子([(N,N',N"-trimethyl-1,4,7-triazacyclononane)2 V2(CN)4(μ-C4N4)])嫁接到电极表面出现有趣物理效应.上述就是在分子水平上研究电子自旋和电荷的分子自旋电子装置.     

超分子配合物的设计与合成方法简述及实例分析

超分子配合物在催化、分子识别、化学吸附、分子磁体、非线性光学、药物合成等领域有着广阔的应用前景。本文从分子设计的角度出发简要介绍了如何选择合适配体合成功能超分子配合物,及合成超分子配合物的几种常用方法。并简要介绍了以5-磺基水杨酸和苯基丙二酸为配体的几种超分子配合物的合成结构。     

分子印迹聚合物的合成进展

介绍了分子印迹的发展及原理,综述了当前分子印迹聚合物的合成进展,分析了分子印迹发展中的问题,并对分子印迹的研究及应用进行了展望。     

分子印迹聚合物的合成进展

介绍了分子印迹的发展及原理,综述了当前分子印迹聚合物的合成进展,分析了分子印迹发展中的问题,并对分子印迹的研究及应用进行了展望。     

Decoherence in crystals of quantum molecular magnets

Quantum decoherence is a central concept in physics. Applications such as quantum information processing depend on understanding it; there are even fundamental theories proposed that go beyond quantum mechanics, in which the breakdown of quantum theory would appear as an 'intrinsic' decoherence, mimicking the more familiar environmental decoherence processes. Such applications cannot be optimized, and such theories cannot be tested, until we have a firm handle on ordinary environmental decoherence processes. Here we show that the theory for insulating electronic spin systems can make accurate and testable predictions for environmental decoherence in molecular-based quantum magnets. Experiments on molecular magnets have successfully demonstrated quantum-coherent phenomena but the decoherence processes that ultimately limit such behaviour were not well constrained. For molecular magnets, theory predicts three principal contributions to environmental decoherence: from phonons, from nuclear spins and from intermolecular dipolar interactions. We use high magnetic fields on single crystals of Fe(8) molecular magnets (in which the Fe ions are surrounded by organic ligands) to suppress dipolar and nuclear-spin decoherence. In these high-field experiments, we find that the decoherence time varies strongly as a function of temperature and magnetic field. The theoretical predictions are fully verified experimentally, and there are no other visible decoherence sources. In these high fields, we obtain a maximum decoherence quality-factor of 1.49?×?10(6); our investigation suggests that the environmental decoherence time can be extended up to about 500 microseconds, with a decoherence quality factor of ～6?×?10(7), by optimizing the temperature, magnetic field and nuclear isotopic concentrations.     

High-temperature metal-organic magnets

For over two decades there have been intense efforts aimed at the development of alternatives to conventional magnets, particularly materials comprised in part or wholly of molecular components. Such alternatives offer the prospect of realizing magnets fabricated through controlled, low-temperature, solution-based chemistry, as opposed to high-temperature metallurgical routes, and also the possibility of tuning magnetic properties through synthesis. However, examples of magnetically ordered molecular materials at or near room temperature are extremely rare, and the properties of these materials are often capricious and difficult to reproduce. Here we present a versatile solution-based route to a new class of metal-organic materials exhibiting magnetic order well above room temperature. Reactions of the metal (M) precursor complex bis(1,5-cyclooctadiene)nickel with three different organics A-TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)--proceed via electron transfer from nickel to A and lead to materials containing Ni(II) ions and reduced forms of A in a 2:1 Ni:A ratio--that is, opposite to that of conventional (low Curie temperature) MA(2)-type magnets. These materials also contain oxygen-based species within their architectures. Magnetic characterization of the three compounds reveals spontaneous field-dependent magnetization and hysteresis at room temperature, with ordering temperatures well above ambient. The unusual stoichiometry and striking magnetic properties highlight these three compounds as members of a class of stable magnets that are at the interface between conventional inorganic magnets and genuine molecule-based magnets.     

脉冲磁场技术在高矫顽力稀土永磁测量领域的应用

简述了超高矫顽力永磁体测量现状,分析了静态磁滞回线仪在测量高矫顽力永磁体时存在的问题及其原因.为解决此问题,采用"f-2f"原理建立了基于脉冲磁场技术的高矫顽力永磁测量装置,该装置能产生最高8 756 kA.m-1的测量磁场,能够测量高矫顽力永磁体的整个磁滞回线.阐述了该脉冲磁场测量装置的优势、组成结构以及涡流修正方法.经过实验验证,该系统具有良好的测量重复性.与国家永磁标准测量装置的对比结果显示:在低矫顽力范围内两者剩磁Br、内禀矫顽力HcJ、磁感应强度矫顽力HcB和最大磁能积(BH)max四个参数的测量偏差在1%以内;在高矫顽力范围,该装置解决了静态磁滞回线仪测量曲线变形的问题.     

Crystal structures and magnetic properties of cyano-bridged 4f-3d complexes

The most recent research progress in the fields of the crystal structure and magnetochemistry for rare earth-transition metal cyano-bridged complexes is reviewed in detail. The emphasis is put on the introduction to the research achievements of our group in this field, including all the types of complexes with different crystal structures in these systems such as dinuclear, trinuclear, one-dimensional chain and hydrogen-bonded network ion-pairs. At the same time a few examples of rare earth-transition metal molecular-based magnets have been found to exhibit excellent magnetochemical properties, such as the long-range magnetic ordering, the higher critical temperature Tc and the stronger coercive force. These results will be expected to promote the research development in this field.     

桥联多核铬配合物的研究进展

多核铬配合物既可以作为葡萄糖耐量因子(GTF)的模型配合物,同时在分子磁材料的研究中占有重要地位,得到了广泛的研究.结合55篇参考文献,概述了近年来氧桥联、氰桥联、硫氰根桥联等多核配合物的研究进展状况.     

Application of high magnetic fields in advanced materials processing

Recently,steady magnetic fields avail-able from cryogen-free superconducting magnets open up new ways to process materials. In this paper,the main results obtained by using a high magnetic field to process several advanced materials are re-viewed. These processed objects primarily include superconducting,magnetic,metallic and nanome-ter-scaled materials. It has been found that a high magnetic field can effectively align grains when fab-ricating the magnetic and non-magnetic materials and make inclusions migrate in a molten metal. The mechanism is discussed from the theoretical view-point of magnetization energy.     

磁力显微镜在Nd-Fe-B硬磁材料上的应用

介绍了磁力显微镜（Magnetic Force Microscopy,MFM）的原理、操作以及用于Nd-Fe-B合金磁畴观察的研究状况。并用这种技术观察了粉末烧结和爆炸压制两种工艺制备的Nd-Fe-B合金的磁畴，给出了它们各自不同的畴结构特征。     

不同稳态的磁弹簧特性分析与实验研究

针对传统金属弹簧在使用中易产生疲劳失效的问题,研究了一种利用磁铁之间相互作用力来产生抗力的新型弹簧——磁弹簧,通过磁弹簧压缩过程中压缩量与力变化关系的分析,发现了磁弹簧是一种变刚度弹簧.论文引入稳态的概念来分类不同类型的磁弹簧,建立了单稳态、双稳态磁弹簧典型结构的力学模型,采用仿真与实验相结合的方法分析了这两种类型磁弹簧的稳态情况和磁铁结构参数对稳态的影响.结果表明磁铁结构参数会影响到磁弹簧的稳态,增大两块磁铁的直径差或厚度差会改变磁弹簧的稳态.