磁性金属基体上非磁性涂层厚度的无损检测方法

论述了磁性金属基体上非磁性涂层厚度的无损测量方法。介绍了机械法和磁阻法两种涂层厚度测量仪的测量原理 。

高磁导率软磁复合材料研究进展

近年来,随着电子产品的高频化、小型化、多元化发展,作为电子元器件重要原材料之一的软磁复合材料受到学术界和工业界的广泛关注,如何获得高磁导率、高饱和磁感应强度、低损耗、低矫顽力的软磁复合材料成为研究重点。本文总结了提高软磁复合材料磁导率的制备工艺现状,概述了不同的制备工艺对材料性能的影响,展望了软磁复合材料成型工艺的发展趋势和发展方向,以期为软磁复合材料的发展提供参考。

高频低损耗软磁复合材料的研究进展

从软磁复合材料的磁性基体设计、绝缘包覆处理和新型制备技术3个方面对软磁复合材料的研究现状进行综述,得出:磁性基体设计时通过对不同特性的磁粉进行性能互补或对基体形态进行控制都可以有效地提高软磁复合材料的密度和磁导率;经绝缘包覆处理可以提高软磁复合材料的电阻率,从而降低其涡流损耗,但是非磁性相绝缘材料的加入会导致复合材料磁导率和饱和磁化强度降低;采用等离子烧结、微波烧结、激光烧结等新型制备技术可以有效改善软磁复合材料的性能.目前软磁复合材料的综合性能已无法满足电子元器件高频化、微型化的发展需求,未来应将研究重点放在优化基体成分设计与粒度配合、开发新的绝缘包覆材料、创新制备工艺、优化制备工艺参数、完善现有理论模型等方面.

Ferromagnetism of Mn-doped ZnO nanoparticles prepared by sol-gel process at room temperature

Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol-gel process.Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 nm.From the analysis of X-ray diffraction,the Mn-doped ZnO nanoparticles are identified to be a wurtzite structure without any impurity phases.The magnetic properties are measured by using superconducting quantum interference device.For the ZnO with 2% Mn doping concentration,a good hysteresis loop indicates fine ferromagnetism with a Curie temperature higher than 350 K.

Crystal Structure and Magnetic Property of 2-（Imidazo[1,2-α]pyri-din-2-yl）- 2-oxoacetic Acid and Its Perchlorate

We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions （hydrogen bonds, anion-Tr or lone- pair-~r interactions）, leading to low magnetic susceptibilities. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.

Voxel-based analyses of magnetization transfer imaging of the brain in hepatic encephalopathy

AIM: To evaluate the spatial distribution of cerebral abnormalities in cirrhotic subjects with and without hepatic encephalopathy (HE) found with magnetization transfer imaging (MTI).METHODS: Nineteen cirrhotic patients graded from neurologically normal to HE grade 2 and 18 healthy control subjects underwent magnetic resonance imaging. They gave institutional-review-board-approved written consent. Magnetization transfer ratio (MTR) maps were generated from MTI. We tested for significant differences compared to the control group using statistical non-parametric mapping (SnPM) for a voxelbased evaluation.RESULTS: The MTR of grey and white matter was lower in subjects with more severe HE. Changes were found in patients with cirrhosis without neurological defi cits in the basal ganglia and bilateral white matter. The loss in magnetization transfer increased in severity and spatial extent in patients with overt HE. Patients with HE grade 2 showed an MTR decrease in white and grey matter: the maximum loss of magnetization transfer effect was located in the basal ganglia [SnPM (pseudo-)t = 17.98, P = 0.0001].CONCLUSION: The distribution of MTR changes in HE points to an early involvement of basal ganglia and white matter in HE.

Electronic Structure and Magnetic Properties of Cu[C(CN)_3]_2 and Mn[C(CN)_3]_2 Based on First Principles

The electronic structure and the magnetic properties of the molecule-based ferromagnets Cu[C（CN）3]2 and Mn[C（CN）3]2 are studied according to first principles within density-functional theory （DFT） and the full potential linearized augmented plane wave （FP-LAPW） method. The total energy, atomic spin magnetic moments, and density of states （DOS） of Cu[C（CN）3]2 and Mn[C（CN）3]2 are all calculated. The calculations reveal that the compounds have a stable ferromagnetic ground state and half-metallic properties. The total spin magnetic moment is 1.0μB for Cu[C（CN）3]2 and 5.0#B for Mn[C（CN）3]e per molecule, the magnetic moment mainly comes from metal atoms, although there is a slight contribution from N and C atoms.

Three interpenetrated copper(Ⅱ) coordination polymers based on a V-shaped ligand:Synthesis,structures,sorption and magnetic properties

Three new CuⅡ coordination polymers,[Cu2(oba)2(H2O)(DMF)].3H2O(1),[Cu4(oba)4(DMF)4].4H2O.DMF(2) and [Cu2(oba)(hmp)2](3)(H2oba = 4,4'-oxybis(benzoic acid),Hhmp = 2-pyridine methanol,DMF = N,N'-dimethylformamide) were synthesized by solvothermal reactions and characterized by single-crystal X-ray diffraction.Both complexes 1 and 2 take three-dimensional(3D) three-fold interpenetrating PtS topology with 1D channels.In complex 3,Cu4 clusters were formed by the chelating hmp ligands,and then the clusters were further linked by oba ligands to form a 3D three-fold interpenetrating dia topology network.For 2,N2 sorption shows type I isotherm with BET surface areas of 562 m2 g-1 and Langmuir surface area of 747 m2 g-1,respectively.At 77 and 87 K,the hydrogen uptakes of complex 2 are 0.89 wt% and 0.57 wt%,respectively.Magnetic investigation showed the ferromagnetic coupling between CuII ions and very weak antiferromagnetic interaction between Cu4 clusters in complex 3.