共查询到20条相似文献,搜索用时 15 毫秒
1.
Lin Zhou Kai Xu Ahmad Zubair Xu Zhang Fangping Ouyang Tomás Palacios Mildred S. Dresselhaus Yongfeng Li Jing Kong 《Advanced functional materials》2017,27(3)
The synthesis of high‐quality 2D MoTe2 with a desired phase on SiO2/Si substrate is crucial to its diverse applications. A side reaction of Te with the substrate Si leading to SiTe and Si2Te3 tends to happen during growth, resulting in the failure to obtain MoTe2. It has been found that molecular sieves can adsorb the silicon telluride byproducts and eliminate the influence of the side reaction during the chemical vapor deposition synthesis of MoTe2. With the help of molecular sieves, few‐layer 1T′ MoTe2 can be grown from the MoOx precursor. Pure 1T′ MoTe2 and 2H MoTe2 regions in centimeter‐sized areas synthesized on the same piece of SiO2/Si substrate can be obtained by using an overlapped geometry. The strategy provides a new method to controllably synthesize MoTe2 with desired phases and can be generalizable to the synthesis of other tellurium‐based layered materials. 相似文献
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Yonas Assefa Eshete Ning Ling Sera Kim Dohyun Kim Geunwoo Hwang Suyeon Cho Heejun Yang 《Advanced functional materials》2019,29(40)
Phase engineering is a breakthrough for various electronic and energy device applications with transition metal dichalcogenides (TMDs). Chemical methods, such as lithium intercalation, are mostly used for phase engineering, which achieves atomically thin flakes and high catalytic performances in several group 6 TMDs including MoS2. However, chemical methods cannot be applied to MoTe2, a widely investigated group 6 TMD with intriguing semiconducting, topological, and catalytic properties. The lack of modifying MoTe2 by chemical methods remains a puzzling issue considering the small energy difference between the polymorphs of MoTe2. Here, a convection‐assisted lithium ion intercalation and phase transition is reported to achieve a vertical heterophase in a MoTe2 crystal. The vertical heterophase in MoTe2 reduces the Schottky barrier with metal electrodes down to 66 meV, enhancing the overall ion conductance for electrochemical hydrogen production. Moreover, the weakened adhesion of the 1T' phase layers on the top and bottom surfaces in the vertical heterophase, formed by the intercalation, enables a unique surface tension‐driven exfoliation of MoTe2 flakes. The heterophase chemical engineering suggests a new platform for hybrid catalysts and next‐generation electronic devices based on 2D materials. 相似文献
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根据神光Ⅱ三次谐波转换中的各种现象,分析了晶体中高频周期相位调制的影响。目前国内大口径KDP晶体在中高频段存在强烈周期性相位调制,相位调制周期约20mm,调制幅度约35nm,导致三次谐波近、远场产生明显的强度调制,实验测得三倍频的近场周期条纹对比度在0.1~0.3之间,周期约12mm,理论分析该周期相位调制导致光束下游元件产生自聚焦风险明显增大,并且会引起三倍频远场畸变分裂,可聚焦能力下降。中高频段的周期调制可能来自于晶体加工过程中真空吸附,需要进一步实验判断并在加工中消除周期性的相位扰动。 相似文献
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光电振荡器的性能及应用 总被引:1,自引:0,他引:1
在对光电振荡器(OEO)的工作原理和特性进行阐述和分析的基础上,总结回顾了边模抑制、降低相位噪声、提高频率稳定性等改善光电振荡器性能的各种技术手段和方案,评述了基于光电振荡器的光脉冲产生、时钟提取等应用,讨论了制约光电振荡器实用化的因素,提出了可能的发展方向和改进措施. 相似文献
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NIR Light‐Triggered Degradable MoTe2 Nanosheets for Combined Photothermal and Chemotherapy of Cancer 下载免费PDF全文
Ning Ma Ming‐Kang Zhang Xiao‐Shuang Wang Lu Zhang Jun Feng Xian‐Zheng Zhang 《Advanced functional materials》2018,28(31)
Telluride molybdenum (MoTe2) nanosheets with wide near‐infrared (NIR) absorbance are functionalized with polyethylene glycol‐cyclic arginine‐glycine‐aspartic acid tripeptide (PEG‐cRGD). After loading a chemotherapeutic drug (doxorubicin, DOX), MoTe2‐PEG‐cRGD/DOX is used for combined photothermal therapy and chemotherapy. With the high photothermal conversion efficiency, MoTe2‐PEG‐cRGD/DOX exhibits favorable cells killing ability under NIR irradiation. Owing to the cRGD‐mediated specific tumor targeting, MoTe2‐PEG‐cRGD/DOX shows efficient accumulation in tumors to induce a strong tumor ablation effect. MoTe2‐PEG‐cRGD nanosheets, which are relatively stable in the circulation, could be degraded under NIR ray. The in vitro and in vivo experimental results demonstrate that this theranostic nanoagent, which could accumulate in tumors to allow photothermal imaging and combined therapy, is readily degradable in normal organs to enable rapid excretion and avoid long‐term retention/toxicity, holding great potential to treat tumor effectively. 相似文献
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Omar A. M. Abdelraouf Aravind P. Anthur Zhaogang Dong Hailong Liu Qian Wang Leonid Krivitsky Xiao Renshaw Wang Qi Jie Wang Hong Liu 《Advanced functional materials》2021,31(48):2104627
Hybrid dielectric metasurfaces have emerged as a promising approach to enhancing near field confinement and thus high optical nonlinearity by utilizing low loss dielectric rather than relatively high loss metallic resonators. A wider range of applications can be realized if more design dimensions can be provided from material and fabrication perspectives to allow dynamic control of light. Here, tunable third harmonic generation (THG) via hybrid metasurfaces with phase change material Ge2Sb2Te5 (GST) deposited on top of amorphous silicon metasurfaces is demonstrated. Fano resonance is excited to confine the incident light inside the hybrid metasurfaces, and an experimental quality factor (Q-factor ≈ 125) is achieved at the fundamental pump wavelength around 1210 nm. Not only the switching between a turn-on state of Fano resonance in the amorphous state of GST and a turn-off state in its crystalline state are demonstrated, but also gradual multistate tuning of THG emission at its intermediate states. A high THG conversion efficiency of η = 2.9 × 10−6% is achieved, which is 32 times more than that of a GST-based Fabry–Pèrot cavity under a similar pump laser power. Experimental results show the potential of exploring GST-based hybrid dielectric metasurfaces for tunable nonlinear optical devices. 相似文献
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Thin layers of ZnS with thicknesses of 400 nm, 500 nm, and 700 nm have been electrodeposited on glass/fluorine-doped tin oxide substrates using a simple two-electrode setup under similar conditions. Structural characterization of the layers using x-ray diffraction (XRD) measurements showed that they were amorphous. The results of optical characterization carried out in the wavelength range of 315 nm to 800 nm using spectrophotometry revealed that the optical properties of the layers are strongly influenced by the film thickness as well as annealing conditions. The values of the refractive index, extinction coefficient, absorption coefficient, and dielectric constant obtained from normal-incidence transmittance spectra were generally lower after annealing, showing also the influence of postdeposition annealing on the deposited ZnS layers. Electrical characterization of the layers, using direct-current current–voltage measurement under dark conditions at room temperature, shows that the resistivity of the as-deposited and annealed layers is in the range of 1.4 × 104 Ω cm to 2.5 × 104 Ω cm and 2.5 × 104 Ω cm to 3.1 × 104 Ω cm, respectively. The results suggest that the optoelectronic properties can be tuned for particular applications by adjusting the thickness of the layers appropriately. 相似文献
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Shan Zhang Lina Wu Wenqiang Shi Junchang Qin Wei Feng Yu Chen Ruifang Zhang 《Advanced functional materials》2023,33(29):2302360
Photodynamic therapy (PDT) as a non-invasive strategy shows high promise in cancer treatment. However, owing to the hypoxic tumor microenvironment and light irradiation-mediated rapid electron–hole pair recombination, the therapeutic efficacy of PDT is dramatically discounted by limited reactive oxygen species (ROS) generation. Herein, a multifunctional theranostic nanoheterojunction is rationally developed, in which 2D niobium carbide (Nb2C) MXene is in situ grown with barium titanate (BTO) to generate a robust photo-pyroelectric catalyst, termed as BTO@Nb2C nanosheets, for enhanced ROS production, originating from the effective electron–hole pair separation induced by the pyroelectric effect. Under the second near-infrared (NIR-II) laser irradiation, Nb2C MXene core-mediated photonic hyperthermia regulates temperature variation around BTO shells facilitating the electron–hole spatial separation, which reacts with the surrounding O2 and H2O molecules to yield toxic ROS, achieving a synergetic effect by means of combinaterial photothermal therapy with pyrocatalytic therapy. Correspondingly, the engineered BTO@Nb2C composite nanosheets feature benign biocompatibility and high antitumor efficiency with the tumor-inhibition rate of 94.9% in vivo, which can be applied as an imaging-guided real-time non-invasive synergetic dual-mode therapeutic nanomedicine for efficient tumor nanotherapy. 相似文献
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惯性约束核聚变驱动器高强度三倍频系统输出能力分析 总被引:3,自引:2,他引:1
以惯性约束核聚变(ICF)驱动器———原型装置(TIL)的研制为背景,针对原型装置首束达标的要求,采用理论模拟指导实验,实验结果考核程序的方法,对影响惯性约束核聚变驱动器大口径高强度三倍频(THG)效率的多种因素进行了详细的分析和研究,并对惯性约束核聚变驱动器高强度三倍频系统的输出能力进行了详细的分析。结果表明,当I1ω(基频光功率密度)为2.7 GW/cm2左右时,实测效率为50%~55%,而理论计算值为60%左右,理论结果和实验结果符合得很好,为原型装置的八束达标和功率平衡提供了相应的实验依据和计算工具。 相似文献
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1 Introduction In recent years short wavelength coherent radiation lying in th blue and UV range has attracted wide attention for a variety o applications, including laser printing, undersea communicatio etc. In view of this, several studies of nonlinear-… 相似文献
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Matthew Delaney Ioannis Zeimpekis Daniel Lawson Daniel W. Hewak Otto L. Muskens 《Advanced functional materials》2020,30(36)
Phase‐change materials (PCMs) are seeing tremendous interest for their use in reconfigurable photonic devices; however, the most common PCMs exhibit a large absorption loss in one or both states. Here, Sb2S3 and Sb2Se3 are demonstrated as a class of low loss, reversible alternatives to the standard commercially available chalcogenide PCMs. A contrast of refractive index of Δn = 0.60 for Sb2S3 and Δn = 0.77 for Sb2Se3 is reported, while maintaining very low losses (k < 10?5) in the telecommunications C‐band at 1550 nm. With a stronger absorption in the visible spectrum, Sb2Se3 allows for reversible optical switching using conventional visible wavelength lasers. Here, a stable switching endurance of better than 4000 cycles is demonstrated. To deal with the essentially zero intrinsic absorption losses, a new figure of merit (FOM) is introduced taking into account the measured waveguide losses when integrating these materials onto a standard silicon photonics platform. The FOM of 29 rad phase shift per dB of loss for Sb2Se3 outperforms Ge2Sb2Te5 by two orders of magnitude and paves the way for on‐chip programmable phase control. These truly low‐loss switchable materials open up new directions in programmable integrated photonic circuits, switchable metasurfaces, and nanophotonic devices. 相似文献
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常温条件下KTP晶体应用于1319nm激光三倍频相位匹配角的测量 总被引:2,自引:0,他引:2
针对常温工作条件下利用磷酸氧钛钾(KTP)晶体对钇铝石榴石(Nd…YAG)晶体1319nm激光三倍频产生440nm蓝色激光的实验,对三倍频KTP晶体的相位匹配角进行了理论计算和实验研究。通过多组色散方程得到KTP晶体的相位匹配角,并计算出相应的有效非线性系数。选取一组结果(θ=84.6°,φ=0°)对KTP晶体切割,利用一台1319nm激光器,将晶体放入腔中,采用旋转晶体偏角和调节温度的方法寻找出三倍频KTP晶体最佳匹配角度(θ=85.04°,φ=0°)。该晶体经过重新切割,440nm蓝色激光输出的光束强度有了明显的提高,最佳工作温度为18℃。 相似文献
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Gd_xY_(1-x)Ca_4O(BO_3)_3晶体非临界相位匹配产生1064nm三次谐波 总被引:1,自引:0,他引:1
通过研究生长不同Gd离子和Y离子配比组份的GdxY1 -xCa4 O(BO3) 3晶体 ,得到了室温下可以实现非临界相位匹配产生 10 64nm三次谐波的新型非线性光学晶体Gd0 .37Y0 .6 3Ca4 O(BO3) 3。报道了GdxY1 -xCa4 O(BO3) 3晶体实现10 64nm三次谐波的相位匹配角。用电光调Q的Nd∶YAG激光器对一块长 11mm ,Y 轴切割的Gd0 .37Y0 .6 3Ca4 O(BO3) 3晶体进行了转换效率的测量 ,其结果为 14 7%。 相似文献
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Yuanlai Fang Zhongxiang Bai Li Yang Qianwei Liu Weiming Xu Jingjiang Wei Kun Yang Qingyuan Wang Jiaxi Cui 《Advanced functional materials》2024,34(18):2314353
The mechanical soft–hard transition of hydrogels is desired in conditions-adaptive deformation and mechanics reconfiguration applications. However, highly efficient, stimuli-responsive, and reversible transition strategies are hard to achieve. Inspired by the supercooling of salt-aqueous solutions, solid and supersaturated hydrogels are prepared based on a hydrophilic polymer network and salt-aqueous solution. The inner crystallization- or melting-induced reversible phase-change realizes the switch between the soft hydrogel (modulus: 0.1 MPa) and rigid composite (modulus: 24.0 MPa). The soft and supersaturated hydrogels easily deform to achieve diverse new 3D models and the unfamiliar soft–hard transition makes temporary shapes be efficiently fixed (hardening). Interestingly, the initial hydrogel's shapes can be regenerated relying on the resilience of the polyacrylamide network when the crystal is melted (softening). Shape memory, complex surface morphology replication, rapid mold application, and self-supporting laminated glass are accomplished by this unique crystallization-melting introduced soft–hard transition. This phase change soft-hard switching strategy will broaden the functionalities of hydrogels. 相似文献
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Yuanlai Fang Xinhong Xiong Li Yang Wanyou Yang Hong Wang Qian Wu Qianwei Liu Jiaxi Cui 《Advanced functional materials》2023,33(27):2301505
The adhesion strategies of the gecko's toe through surface adaptation of spatulas to increase contact area and the snail's epiphragm via dehydration-induced solidification to lock interfaces are combined to design a class of adhesion-switchable hydrogels. The hydrogels are made via incorporating CH3COONa·3H2O salt (SA) into polyacrylamide (PAM) aqueous networks to construct supersaturated and stimuli-responsive phase change materials (PAM-SA). The crystallization dramatically strengthens the mechanical properties, and tensile Young's moduli are 340.7 and 0.1 MPa for crystalline C-PAM-SA-120% and soft PAM hydrogel. As a result, PAM-SA-120% shows excellent adhesive performance (adhesion strength, 348 kPa) compared with PAM hydrogel adhesive (adhesion strength, 7 kPa). The stimuli-induced crystallization from H-PAM-SA-120% phase change hydrogels releases thermal controllably, which can be utilized for thermochromic materials and thermotherapy. 相似文献
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Genetically Controlled Lysosomal Entrapment of Superparamagnetic Ferritin for Multimodal and Multiscale Imaging and Actuation with Low Tissue Attenuation 下载免费PDF全文
Christoph Massner Felix Sigmund Susanne Pettinger Markus Seeger Carolin Hartmann Natalia P. Ivleva Reinhard Niessner Helmut Fuchs Martin Hrabě de Angelis Anja Stelzl Neha Lal Koonakampully Hannes Rolbieski Ulf Wiedwald Marina Spasova Wolfgang Wurst Vasilis Ntziachristos Michael Winklhofer Gil G. Westmeyer 《Advanced functional materials》2018,28(19)
Nanomaterials are of enormous value for biomedical applications because of their customizable features. However, the material properties of nanomaterials can be altered substantially by interactions with tissue thus making it important to assess them in the specific biological context to understand and tailor their effects. Here, a genetically controlled system is optimized for cellular uptake of superparamagnetic ferritin and subsequent trafficking to lysosomes. High local concentrations of photoabsorbing magnetoferritin give robust contrast in optoacoustic imaging and allow for selective photoablation of cells overexpressing ferritin receptors. Genetically controlled uptake of the biomagnetic nanoparticles also strongly enhances third‐harmonic generation due to the change of refractive index caused by the magnetite–protein interface of ferritins entrapped in lysosomes. Selective uptake of magnetoferritin furthermore enables sensitive detection of receptor‐expressing cells by magnetic resonance imaging, as well as efficient magnetic cell sorting and manipulation. Surprisingly, a substantial increase in the blocking temperature of lysosomally entrapped magnetoferritin is observed, which allows for specific ablation of genetically defined cell populations by local magnetic hyperthermia. The subcellular confinement of superparamagnetic ferritins thus enhances their physical properties to empower genetically controlled interrogation of cellular processes with deep tissue penetration. 相似文献