二硫化钼纳米微粒改性聚乙烯研究

通过红外、热重、差热等分析手段及拉伸实验,研究了二硫化钼(MoS2)纳米球与纳米片对聚乙烯(PE)塑料性能的影响。发现添加MoS2后,PE塑料的降解温度、结晶峰温度与玻璃化温度均有提高,同时材料的拉伸强度也得到明显提升,其中MoS2纳米片对PE的改性效果最佳。MoS2纳米球与MoS2纳米片的微观结构不同,因而导致了它们改性PE塑料效果的差别。     

化学气相沉积法制备富勒烯结构二硫化钼纳米粒子

以MoO3和S粉为原料,高纯氩气为载气和反应气氛,在石英管反应器中,用化学气相沉积法制备富勒烯结构MoS2纳米粒子,用XRD对产品的成分进行测量,SEM观察产品的整体微观形貌。结果表明,在900℃下,通氩气1 cm3/min,保温8 h,制备了平均粒径在250 nm左右的高纯富勒烯结构MoS2纳米粒子。     

油溶性二硫化钼纳米微粒的制备及抗磨性能

通过共沉淀法制备出Py DDP表面修饰的二硫化钼纳米微粒。采用FT-IR、TEM、元素分析对产物组成和结构进行表征,并考察了其在有机溶剂中的分散性。结果表明:所得表面修饰Mo S2纳米微粒尺寸在30nm~50nm之间,其在氯仿、丙酮和基础油中具有良好的分散性。利用四球极压抗磨试验考察了其摩擦学性能,磨损试验结果表明表面修饰的Mo S2纳米微粒具有良好的抗磨、减摩性能。     

锂离子电池二硫化钼基负极材料研究进展

锂离子电池以其便携、无记忆效应、循环寿命长等特点广泛应用于移动电子设备、电动汽车等领域。负极材料的改进是制备新型高性能锂离子电池的重要环节。具有类石墨烯结构的二硫化钼是极具发展潜力的锂离子电池用负极材料。但纯二硫化钼导电性差、充放电过程中体积膨胀率高,导致其可逆容量低、容量保持率差。复合化与纳米化是解决上述问题的有效途径。综述了近年来用于锂离子电池负极材料的二硫化钼基复合材料研究进展,重点介绍了二硫化钼/碳和二硫化钼/过渡金属化合物体系的形貌特征、比容量、循环稳定性等,并对二硫化钼基负极材料的发展趋势进行了展望。     

二维层状二硫化钼复合材料的研究进展及发展趋势

二维层状二硫化钼因其独特的结构已经成为二维结构材料领域中新兴的研究热点。它拥有特殊的可调节带隙及优异的光电性能。综述了二维层状二硫化钼的制备方法和优异性能;作为其发展的一个重要方向,对二维层状二硫化钼复合材料的最新研究进行了综述并探讨了复合材料性能提升的机制。提出了对二维层状二硫化钼复合材料相关研究的建议和展望。     

Ferromagnetism in exfoliated tungsten disulfide nanosheets

Two-dimensional-layered transition metal dichalcogenides nanosheets have attracted tremendous attention for their promising applications in spintronics because the atomic-thick nanosheets can not only enhance the intrinsic properties of their bulk counterparts, but also give birth to new promising properties. In this paper, ultrathin tungsten disulfide (WS₂) nanosheets were gotten by liquid exfoliation route from its bulk form using dimethylformamide (DMF). Compared to the antiferromagnetism bulk WS₂, ultrathin WS₂ nanosheets show intrinsic room-temperature ferromagnetism (FM) with the maximized saturation magnetization of 0.004 emu/g at 10 K, where the appearance of FM in the nanosheets is partly due to the presence of zigzag edges in the magnetic ground state at the grain boundaries.     

上转换发光材料在不同防伪领域的研究进展Q

稀土上转换纳米粒子（UCNPs）能够吸收低能量的红外光并转换为高能量的紫外或可见光,其具有自体发光背景低、发光颜色可调、荧光寿命长和光稳定性好等优异的光学性能,此外,其还具有可加工性高、表面功能化便捷等特点,因而如今已经成为了荧光防伪技术的研究前沿和研究热点,应用前景十分广泛。本文综述了UCNPs的发光机制和一系列制备方法并分析优缺点,阐述了近年来其在标签、图案、编码等荧光防伪领域应用的相关优秀研究成果。进一步地,还探讨了UCNPs在荧光防伪领域应用上所存在的问题和面临的挑战,提出了未来可能的发展方向。     

纳米WS2润滑油添加剂在直流磁场下的摩擦磨损特性

在四球摩擦磨损实验机摩擦区域添加了直流磁场发生装置,研究了添加经修饰的纳米WS₂润滑油在直流磁场作用下的摩擦磨损性能,用扫描电镜（SEM）配合能谱仪（EDS）及X射线光电子能谱仪（XPS）对钢球磨斑区域表面形貌和典型元素的含量及化学状态进行了分析,并探讨了相关的摩擦学机理。实验结果表明：经修饰后的纳米WS₂在150SN基础油中稳定性良好,含纳米WS₂的润滑油体现出更好的润滑性能,在纳米WS₂含量相同时,直流磁场下的润滑油抗磨减摩效果更好。直流磁场对纳米WS₂有一定的聚集效应,并会提高摩擦化学反应发生的概率。     

Reversible upconversion switching for Ho/Yb codoped (K,Na)NbO3 ceramics with excellent luminescence readout capability

Luminescent readout capability for photochromic materials plays a critical role in 3D optical data storage applications, especially for inorganic photochromic materials in the solid‐state form. In our previous studies, we found that the luminescent readout capability can be improved using two or multiple‐photon excited luminescent mode (upconversion), which can effectively decrease the destruction degree of the excitation energies to the stored information during the luminescent “reading” process. However, the luminescent readout performance is unsatisfactory owing to the absence of nondestructive luminescence readout capability. Herein, we report a new solid‐state photochromic material with excellent upconversion readout capability: Ho³⁺/Yb³⁺ codoped (K,Na)NbO_3. Upon 407 nm light irradiation, the luminescent switching contrast (ΔR_t) is up to 78%. Particularly, the materials almost have no any re‐absorption to 980 nm light, exhibiting extremely low destruction to information recording points. The luminescent readout intensity retains 96% after constant 980 nm irradiation for 4 minutes at a high pumping power of 1W, which is superior to our previously reported results (Er/Yb codoped Bi_2.5Na_0.5Nb₂O₉ materials). This work would help to further develop new inorganic photochromic materials with high performance to satisfy the requirements for optical storage devices.     

上转换发光材料在不同防伪领域的研究进展Q

稀土上转换纳米粒子(UCNPs)能够吸收低能量的近红外光并转换为高能量的紫外或可见光,具有自体发光背景低、发光颜色可调、荧光寿命长和光稳定性好等优异的光学性能,还具有可加工性高、表面功能化便捷等特点,已成为荧光防伪技术的研究前沿和研究热点,应用前景广泛.该文综述了UCNPs的发光机制和制备方法,阐述了近年来其在标签、图案、编码等荧光防伪领域应用的相关研究成果.进一步地探讨了UCNPs在荧光防伪领域应用上所存在的问题和面临的挑战,提出了未来可能的发展方向.     

掺杂上转换纳米粒子的温敏性发光水凝胶的制备及性能

采用水热法,以聚乙烯亚胺(PEI)为表面改性剂,合成了水分散性较好的上转换纳米粒子(UC@PEI NPs).考察了溶剂组成、反应时间、PEI分子量与加入量对UC@PEI NPs发光强度的影响,并进行了表征.结果显示:V(H2O)∶V(EG)=1∶1,PEI(Mw=10000)加入量为1.2 g,并于200 ℃反应8 h...     

Nonlinear negative transmittance at a CW 980‐nm laser diodes pumping in Yb3+:CaF2 nanocrystals‐embedded glass ceramics

Cooperative upconversion luminescence (CUCL) occurs in spectral regions in which single ions do not have energy levels. However, all results reported so far are concentrated on luminescence properties from Yb³⁺ ions‐doped various hosts. Here, we report the observation of nonlinear negative transmittance (NNT) at continuous‐wavelength (CW) 980‐nm laser diodes (LDs) pumping in silicate oxyfluoride glass ceramics (GCs)‐containing CaF₂:Yb³⁺ nanocrystals. The unique optical nonlinearity is analyzed based on energy‐level transitions, dynamic evolution, rate equation, and power transmission equation, which can be explained as the cooperative optical absorption for the intense CUCL of Yb³⁺ ions. The NNT in the CaF₂:Yb³⁺ nanocrystals‐embedded GCs can be tailored with the power of a CW 980‐nm LDs, which possesses potential for the development of future optical limiters and switches.     

2,5-二氰基-1,4-二(4′-甲氧基苯乙烯基)苯的合成和非线性光学性质

报道了具有典型D-A-D型共轭结构的反式2,5-二氰基-1,4-二(4′-甲氧基苯乙烯基)苯(DCHO)的合成.用核磁、红外和元素分析进行了表征.测试了紫外吸收光谱、单光子荧光光谱、双光子荧光光谱及双光子吸收截面.在800 nm的飞秒脉冲激光激发下,标题化合物发出很强的绿色上转换荧光.化合物2,5-二氰基-1,4-二(4′-甲氧基苯乙烯基)苯的最大吸收波长、单光子发射波长、最大双光子荧光波长、荧光量子产率、双光子吸收系数及双光子吸收截面分别是393 nm、470 nm、475 nm、0.12、0.8 cm/GW、270 GM.这些数据表明,对位甲氧基的D-A-D型化合物具有较好的双光子吸收性能,DCHO是双光子荧光显微与成像应用的一个良好的候选材料.