High enhanced magnetization in carbon-doped Mn3Ga thin films

Carbon-doped Mn₃Ga thin films were grown on Si/SiO₂ substrates using rf magnetron sputtering technique. The tetragonal D0₂₂–type crystalline structure of ferrimagnetic Mn₃Ga is preserved on the Mn₃GaC_x films upon carbon concentrations up to x = 0.5, whereas higher concentrations lead to the formation of the antiperovskite Mn₃GaC phase. Geometry optimization calculations using the density functional theory were performed on a 2 × 2 × 2 Mn₃GaC_0.25 supercell with C in different positions in order to find that the most stable position for the C is interstitial octahedral site. Magnetic M(H) loops show that saturation magnetization M_s of Mn₃GaC_0.25 is enhanced to 200 kAm⁻¹ (from M_s = 90 kAm⁻¹ for undoped films). The increase of the C concentration leads to a reduction of the Curie temperature from 770 K to ∼420 K at the same time that the lattice cell suffers an expansion. The enhancement of M_s is explained in terms of a 90° ferromagnetic superexchange Mn-C-Mn interaction.     

Layered Nanoprobe for Long‐Lasting Fluorescent Cell Label

A long‐lasting particle‐based fluorescent label is designed for extended cell imaging studies. This onion‐like nanoprobe is constructed through layer‐by‐layer fabrication technology. The nanoprobes are assembled with multiple layers of optically quenched polyelectrolytes, the fluorescence signal of which can be released later by intracellular proteolysis. Upon incubation with cells, the assembled nanoprobes are taken up efficiently. The tight packing and layered assembly of the quenched polyelectrolytes slow subsequent intracellular degradation, and then result in a prolonged intracellular fluorescence signal for up to 3 weeks with no noticeable toxicity.     

添加剂对Cu/Co多层膜电结晶成核机理及磁性的影响

在硼酸镀液中以单晶S i(111)为基底用双槽法制备Cu/Co多层膜,在镀液中分别加入了镀铜添加剂2000#和镀钴添加剂5#。探讨了镀层电结晶成核机理,在基础镀液中铜电结晶为三维连续成核过程,钴电结晶在较低电位下为三维连续成核,在较高电位下为三维瞬时成核过程。加入添加剂后,铜、钴电结晶均为三维瞬时成核过程。测试了Cu/Co多层膜的磁性能;添加剂能提高多层膜的磁性能,无添加剂的Cu/Co多层膜的巨磁阻(GMR)值约为5%,而在加入了添加剂后,其GMR值高达52%。     

溅射沉积Cu/W纳米多层膜结构与性能

以单晶硅和聚酰亚胺为衬底,用磁控溅射沉积调制周期λ=25~150 nm、调制比η=0.5~2的Cu/W纳米多层膜,用XRD、SEM、EDS、AFM、微力测试系统、纳米压痕仪和四探针法对多层膜微观结构、表面形貌和力学及电学性能进行研究。结果表明:λ和η显著影响多层膜结构和性能。多层膜Cu层和W层均为纳米晶结构,分别呈Cu(111)和W(110)择优取向。W(110)晶面间距减小且减幅与1/λ或η值呈正相关,Cu/W层间界面处存在扩散混合层。表面Cu层晶粒尺寸随Cu层厚增加而增大。裂纹萌生临界应变εc总体上随λ增大或η减小而下降,屈服强度σ0.2、显微硬度H和电阻率ρ总体上均与λ或η呈负相关。因Cu层和W层厚度随λ或η的变化而改变,相应地改变了Cu层晶粒度及其晶界密度、W层体积分数和Cu/W层间界面数量,使位错运动能力及电子散射效应变化,最终改变Cu/W纳米多层膜性能。     

Multilayered YSZ–Ag–Mo/TiN adaptive tribological nanocomposite coatings

Adaptive nanocomposite coatings provide low friction in broad ranges of environmental conditions through the formation of lubricious surfaces resulting from interactions with the ambient atmosphere. Designing adaptive coatings to withstand wear through repeated thermal cycles is particularly difficult since most demonstrate irreversible changes in surface composition and morphology. This permanent change in the condition of the surface limits the utility of adaptive coatings in applications where thermal cycling is expected. Moreover, some lubrication mechanisms occur over the entire coating surface in addition to the area experiencing wear, which results in a significant waste of lubricant. In an effort to increase the wear lifetime and move toward thermal cycling capabilities of solid adaptive lubricants, a multilayer coating architecture incorporating two layers of adaptive YSZ–Ag–Mo nanocomposite lubricant separated by a TiN diffusion barrier was produced. The multilayer coating lasted over five times longer than a monolithic adaptive coating of identical composition and total thickness for dry sliding tests at 500 °C in air. Analysis of the structure and composition of the films after heating suggests directed, lateral diffusion of lubricant beneath the diffusion barrier toward the wear scar as a mechanism for the increased wear life of the multilayer coating.     

Preparation of Phospholipid Multilayer Patterns of Controlled Size and Thickness by Capillary Assembly on a Microstructured Substrate

By dragging a phospholipid solution on microstructured silicon surfaces, phospholipid molecules are selectively deposited inside the microstructures to get regular phospholipid multilayer patterns of controlled thickness over a large scale (～cm²). By varying the dragging speed, the thickness of the patterns varies between 28 and 100 nm on average (7 to 25 bilayers). Electroswelling of phospholipid multilayer patterns leads to the formation of giant liposomes of controlled size and narrow size distributions.     

Mesostructured Thin Films as Responsive Optical Coatings of Photonic Crystals

A synthetic route is presented to attain high‐optical‐quality multilayered structures that result from coupling ordered mesoporous titanium oxide thin films to the surface of a dense one‐dimensional photonic crystal. Such architectures present spectrally well‐defined photon resonant modes localized in the outer coating that finely respond to physicochemically induced modifications of its pore volume. The potential of these porous coatings in detection of environmental changes through variations of the photonic response of the ensemble is demonstrated by performing isothermal optical reflectance measurements under controlled vapor‐pressure conditions.     

TiN／Ag多层膜的生物相容性研究

使用离子束辅助沉积（IBAD）的方法，在医用不锈钢317L的基底上制备TiN／Ag多层膜．在TiN／Ag多层膜具有良好的抗茵性和抗腐蚀性的研究基础上，通过细胞毒性试验和溶血试验评价了TiN／Ag多层膜的生物相容性．试验结果表明：TiN／Ag多层膜样品的细胞毒性等级在0～1之间；溶血率〈5％，符合生物医学材料的标准．这些说明TIN／Ag多层膜不仅具有抗菌性和抗腐蚀性，而且具有良好的生物相容性．     

Perpendicular exchange bias of （Pt/Co）n/FeMn multilayers

(Pt/Co)n/FeMn multilayers with perpendicular anisotropy (PA) were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias (PEB), Hex, on the thickness of the FeMn antiferromagnet (AFM) layer is similar to that of in-plane exchange bias. The value of Hex for the (Pt/Co)3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.