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KTN thin films prepared by pulsed laser deposition on transparent single crystal quartz(100)

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Science China(Physics,Mechanics & Astronomy) 2005年第1期48卷 33-43页

作者： WANG Xiaodong, PENG Xiaofeng & ZHANG Duanming laboratory of phase change and interfacial transport phenomena, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China laboratory of phase change and interfacial transport phenomena Department of Thermal Engineering Tsinghua University Beijing China Department of Physics Huazhong University of Science and Technology Wuhan China

Using the Sol-Gel method to produce the KTN ultrafine powder and the sintering technique with K2O atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). Since the thermal stress sustained by the quartz is relatively small, the limit temperature of the quartz substrates(300℃) is much lower than that of the P-Si substrates (560℃); the prepared thin film is at amorphous state. Increasing the pulsed laser energy density in the process incorporated with annealing the film after deposition at different temperatures converts the amorphous films into crystal. The optimal pulsed laser energy density and annealing temperature were 2.0 J/cm2 and 600℃, respectively. A discussion was made to understand the mechanism of film production at relatively low substrate temperature by PLD and effects of the annealing temperatures on the forming of the perovskite phase, and optimal conditions for the orientation of the crystal grain.

关键词： PLD technology, KTN thin film, single crystal quartz, pulsed energy density, annealing, perovskitephase.

Contact Angle Hysteresis and Hysteresis Tension on Rough Solid Surface

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Chinese Journal of Chemical Engineering 2004年第5期12卷 615-621页

作者：王晓东彭晓峰王补宣 laboratory of phase change and interfacial transport phenomena Department of Thermal Engineering Tsinghua University Beijing 100084 China

Observation and measurement were conducted to investigate contact angle andits hysteresis on rough surface. The experimental results indicate that the increase in solidsurface roughness enlarges advancing contact angle and decreases receding contact angle, resultingin enhanced hysteresis. It was observed that when Young''s contact angle θ_Y < 90°, as theroughness of solid surface increased the extent of the decrease in receding contact angle exceededthat of the increase in advancing contact angle. Based on the experimental observations, the conceptof hysteresis tension was introduced to describe the contact angle hysteresis behavior on roughsolid surface. The model provides a thoughtful understanding of the physical nature of contact anglehysteresis, in particular an instructive description of the influence of surface roughness on thehysteresis. The prediction of the model is found in quite good agreement with the experimentalobservation and measurement.

关键词： contact angle hysteresis roughness hysteresis tension sessile drop

Liquid exploding emission during boiling nucleation in capillary tubes

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Chinese Science Bulletin 2010年第20期55卷 2186-2195页

作者： WU Di PENG XiaoFeng laboratory of phasechange and interfacial transport phenomena Department of Thermal Engineering Tsinghua University Beijing 100084China

A series of experiments was conducted to visually observe boiling nucleation phenomena in micro capillary tubes employing a high speed *** a higher heat flux the liquid in capillary tubes was emitted instantaneously rather than generating nucleate boiling,which is referred as liquid exploding emission in this *** critical emission heat flux and temperature corresponding to this phenomenon were measured for tubes with different heating lengths and arrangements of two end *** nucleation and liquid film evaporation played critical roles in different stages during exploding *** critical emission volumetric heat was introduced to describe the conditions of the emission instead of heat flux,and theoretical discussions were conducted to explore the influences of thermal properties and geometrical configuration,particularly heating length and asymmetry of two end sections of tubes.

关键词：爆炸过程微毛细管热排放核沸腾液体高热通量高速CCD 成核现象

ADSORPTION OF NANO-PARTICLES ON BUBBLE SURFACE IN NANO-PARTICLE SUSPENSION

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China Particuology 2005年第4期3卷 208-212页

作者： Buxuan Wang Chunhui Li Xiaofeng Peng laboratory of phase-change and interfacial transport phenomena Department of Thermal Engineering Tsinghua UniversityBeijing 100084 P. R. China

The adsorption of nano-particles on bubble surface is discussed for saturated boiling on thin wire of nano-particle suspensions. Owing to the decrease of surface tension for suspensions, the nano-particles tend to adsorb on the bubble surface to decrease the Gibbs free energy for stability, and meanwhile the velocity of nano-particles would be smaller than that of bubble growth. The long-range van der Waals force existing between “water particles” and nano-particles is considered the attractive force between the nano-particles and the bubble surface. Thus, the nano-particles would attach on the bubble surface if the particle-surface distance is smaller than its critical value. The distribution of nano-particles on the bubble surface and in the adjacent region is also investigated.

关键词： nano-particle suspension attachment critical distance

Crystal face dependent intrinsic wettability of metal oxide surfaces

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National Science Review 2021年第1期8卷 109-116页

作者： Zhongpeng Zhu Zhenwei Yu Frank F.Yun Deng Pan Ye Tian Lei Jiang Xiaolin Wang Key laboratory of Bio-inspired Materials and interfacial Science Technical Institute of Physics and ChemistryChinese Academy of Sciences Key laboratory of Bio-inspired Smart interfacial Science and Technology of Ministry of Education School of ChemistryBeihang University Institute for Superconducting and Electronic Materials Australian Institute for Innovative MaterialsUniversity of Wollongong

Knowledge of intrinsic wettability at solid/liquid interfaces at the molecular level perspective is significant in understanding crucial progress in some fields, such as electrochemistry, molecular biology and earth science. It is generally believed that surface wettability is determined by the surface chemical component and surface topography. However, when taking molecular structures and interactions into consideration,many intriguing phenomena would enrich or even redress our understanding of surface wettability. From the perspective of interfacial water molecule structures, here, we discovered that the intrinsic wettability of crystal metal oxide is not only dependent on the chemical components but also critically dependent on the crystal faces. For example, the （1■02） crystal face of α-Al;O;is intrinsically hydrophobic with a water contact angle near 90°, while another three crystal faces are intrinsically hydrophilic with water contact angles interfacial water molecules on each crystal face hold various orientations. Herein, the third crucial factor for surface wettability from the perspective of the molecular level is presented, that is the orientations of adsorbed interfacial water molecules apart from the macro-level chemical component and surface topography. This study may serve as a source of inspiration for improving wetting theoretical models and designing controllable wettability at the molecular/atomic level.

关键词： anisotropic wettability α-Al2O3 interfacial water layer surface energy DFT simulation

System-size effect on the friction at liquid-solid interfaces

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Applied Mathematics and Mechanics(English Edition) 2020年第3期41卷 471-478页

作者： Liang ZHAO Jiajia SUN Xian WANG Li ZENG Chunlei WANG Yusong TU College of Physical Science and Technology Yangzhou UniversityYangzhou 225009Jiangsu ProvinceChina School of Physics and Electronics Nanning Normal UniversityNanning 530023China Division of interfacial Water and Key laboratory of interfacial Physics and Technology Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201800China

The friction at the liquid-solid interfaces is widely involved in various phenomena ranging from nanometer to micrometer scales. By the molecular dynamic(MD)simulation, the friction properties of liquid-solid interfaces at the molecular level are calculated via the Green-Kubo relation. It is found that the system size will influence the value of the friction coefficient, especially for the solid surfaces with the larger polar charge. The value of the friction coefficient decreases with the increase in the system size and converges at large system sizes. The large polar charge will lead to a significant friction coefficient. However, the diffusion of water molecules on this surface is almost a constant, indicating that the diffusion coefficient seems to be independent of the system size and polar charge. This work provides insights for the selection of the system size in modeling the frictional properties of hydrophobic/hydrophilic surfaces.

关键词： Green-Kubo relation liquid-solid interface system-size effect friction coefficient

Multiscale patterning of a metallic glass using sacrificial imprint lithography

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Microsystems & Nanoengineering 2015年第1期1卷 16-25页

作者： Jonathan P.Singer Candice I.Pelligra Noga Kornblum Youngwoo Choo Manesh Gopinadhan Punnathat Bordeenithikasem Jittisa Ketkaew Seng Fatt Liew Hui Cao Jan Schroers Chinedum O.Osuji Department of Mechanical and Aerospace Engineering Rutgers UniversityPiscatawayNJ 08854USA Department of Chemical and Environmental Engineering Yale UniversityNew HavenCT 06511USA Department of Chemical and Environmental Engineering Center for Research on Interfacial PhenomenaYale UniversityNew HavenCT 06511USA Department of Mechanical Engineering and Materials Science Yale UniversityNew HavenCT 06511USA Department of Applied Physics Yale UniversityNew HavenCT 06511USA Department of Mechanical Engineering and Materials Science Center for Research on Interfacial PhenomenaYale UniversityNew HavenCT 06511USA

Bulk metallic glasses(BMGs)have been developed as a means to achieve durable multiscale,nanotextured surfaces with desirable properties dictated by topography for a multitude of *** barrier to this achievement is the lack of a bridging technique between macroscale thermoplastic forming and nanoimprint lithography,which arises from the difficulty and cost of generating controlled nanostructures on complex geometries using conventional top-down *** difficulty is compounded by the necessary destruction of any resulting reentrant structures during rigid *** have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide(ZnO)*** is established that such structures can be grown inexpensively and quickly with tunable morphologies on a wide variety of substrates out of solution,which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up *** this way,we achieve metallic structures that simultaneously demonstrate features from the macroscale down to the nanoscale,requiring only the top-down fabrication of macro/microstructured *** detachment of the formed part from the multiscale molds,the ZnO remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the BMGs *** ability to pattern metallic surfaces in a single step on length scales from centimeters down to nanometers is a critical step toward fabricating devices with complex shapes that rely on multiscale topography for their intended functions,such as biomedical and electrochemical applications.

关键词： bulk metallic glasses nanoimprint multiscale structures optical properties

Hydrophobic nanochannel self-assembled by amphipathic Janus particles confined in aqueous nano-space

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Chinese Physics B 2018年第3期27卷 191-196页

作者： Gang Fang Nan Sheng Tan Jin Yousheng Xu Hai Sun Jun Yao Wei Zhuang Haiping Fang Division of interfacial Water and Key laboratory of interfacial Physics and Technology Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201800China State Key laboratory of Structural Chemistry Fujian Institute of Research on Structure of MattersChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China School of Light Industry Zhejiang University of Science and TechnologyHangzhou 310023China School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266555China

Hydrophobic nanochannel plays a significant role in many physical, biological, and geological phenomena and ex- hibits impressive applications due to both its ubiquitous distribution and great ability to transport hydrophobic molecules, including various oils and gases. Based on theoretical modeling, we herein reveal that the amphipathic Janus nanoparticles have a large probability to self-assemble into uninterrupted hydrophobic nanochannels inside the aqueous nano-space, al- though there are large portions of the Janus nanoparticles to be hydrophilic. The key to this observation is the attractions between the hydrophobic regimes on neighboring amphipathic Janus particles through hydrophobic interaction in aqueous nano-space. More surprisingly, the permeation efficiency of hydrophobic molecules through the uninterrupted hydrophobic channel in Janus particles aggregate is even higher than that in the aggregate of hydrophobic particles. We note that the proposed amphipathic Janus particles can be transported to the appropriate positions by the water since the hydrophilic regimes still remain a strong particle-water interaction. We also note that most natural subsurface rocks are not completely hydrophobic or hydrophilic but have complex surfaces with inhomogeneous wetting property. Our work therefore provides a detailed molecular level understanding of the formation of underground strata as well as the new insight for constructing the artificial hydrophobic channels for various applications, such as the design of proppants to enhance the recovery of the unconventional oil/gas.

关键词： amphipathic Janus particle self-assembly uninterrupted hydrophobic channel water blockage

Direct observation of spreading precursor liquids in a corner

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National Science Review 2023年第7期10卷 196-202页

作者： Weining Miao Shihao Tian Quanzi Yuan Ye Tian Lei Jiang Key laboratory of Bioinspired Smart interfacial Science Technical Institute of Physics and Chemistry Chinese Academy of Sciences School of Future Technology University of Chinese Academy of Sciences State Key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

Precursor liquid is a nanoscale liquid creeping ahead of the macroscopic edge of spreading liquids,whose behaviors tightly correlate with the three-phase reaction efficiency and patterning ***,the important spatial-temporal characteristic of the precursor liquid still remains obscure because its real-time spreading process has not been directly ***,we report that the spreading ionic liquid precursors in a silicon corner can be directly captured on video using in situ scanning electron *** situ spreading videos show that the precursor liquid spreads linearly over time(ΔL～ΔT) rather than obeying the classic Lucas-Washburn law(l～t1/2) and possesses a characteristic width of ～250-310 *** analyses and molecular dynamics simulations demonstrate that the unique behaviors of precursor liquids originate from the competing effect of van der Waals force and surface *** findings provide avenues for directly observing liquid/solid interfacial phenomena on a microscopic level.

关键词： precursor liquid spreading spatial–temporal characteristic direct observation corner ionic liquids