scholarly journals Comparison of Structure Stability of Graphene and Mxene by Peak Force Tapping Mode of Atomic Force Microscope

2021 ◽  
Author(s):  
Cai Shen
Keyword(s):  
Etching Rate ◽  
Peak Force ◽  
Atmospheric Environment ◽  
Damage Effect ◽  
Structure Stability ◽  
Two Dimensional ◽  
Tapping Mode ◽  
Scanning Time ◽  
The Stability

In this paper, the structural stability of graphene and Mexene was compared by peak force tapping mode of AFM. When in-situ scanning of two-dimensional material of reduced graphene oxide (rGO), the morphology of rGO did not change with time, which indicated that peak force tapping mode had no damage effect on the stable structure surface; while when in-situ scanning of two-dimensional material V2C, nano-etching occurred on the surface of V2C, and the morphology surface area decreased with scanning time. The data processing software was used to analyze the area change and calculate the nano etching rate. It was found that the average nano-etching rate increased with the increase of the peak force, and the etching rate in the atmospheric environment was higher than that in the glove box (Ar atmosphere, the H2O and O2 content was less than 1 ppm), which indicated that the moisture in the atmosphere had an impact on the stability of the material and would accelerate the nano-etching. This study shows that the peak force tapping mode of AFM can be used to qualitatively characterize the stability of two-dimensional materials

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

Concomitant induction to few-layer and 1T-rich two-dimensional MoS2 by rigid segment-containing polysulfide as a sulfur source and in situ intercalator

2021 ◽  
Author(s):  
Yijuan Wang ◽  
Jianzhi Wang ◽  
Jie Liu ◽  
Zhuangwei Xiao ◽  
Yanan Xue ◽  
...  
Keyword(s):  
Sulfur Source ◽  
Two Dimensional ◽  
Rigid Segment

A rigid segment-containing polysulfide was used as a sulfur source and in situ intercalator to induce the formation of few-layer and 1T-rich MoS2.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

scholarly journals A Self-Established “Machining-Measurement-Evaluation” Integrated Platform for Taper Cutting Experiments and Applications

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 929
Author(s):  
Xudong Yang ◽  
Zexiao Li ◽  
Linlin Zhu ◽  
Yuchu Dong ◽  
Lei Liu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precision Machining ◽  
Two Dimensional ◽  
Dimensional Image ◽  
Two Dimensional Image ◽  
Integrated Platform ◽  
Hard And Brittle Materials ◽  
Ultra Precision ◽  
Cutting Experiments

Taper-cutting experiments are important means of exploring the nano-cutting mechanisms of hard and brittle materials. Under current cutting conditions, the brittle-ductile transition depth (BDTD) of a material can be obtained through a taper-cutting experiment. However, taper-cutting experiments mostly rely on ultra-precision machining tools, which have a low efficiency and high cost, and it is thus difficult to realize in situ measurements. For taper-cut surfaces, three-dimensional microscopy and two-dimensional image calculation methods are generally used to obtain the BDTDs of materials, which have a great degree of subjectivity, leading to low accuracy. In this paper, an integrated system-processing platform is designed and established in order to realize the processing, measurement, and evaluation of taper-cutting experiments on hard and brittle materials. A spectral confocal sensor is introduced to assist in the assembly and adjustment of the workpiece. This system can directly perform taper-cutting experiments rather than using ultra-precision machining tools, and a small white light interference sensor is integrated for in situ measurement of the three-dimensional topography of the cutting surface. A method for the calculation of BDTD is proposed in order to accurately obtain the BDTDs of materials based on three-dimensional data that are supplemented by two-dimensional images. The results show that the cutting effects of the integrated platform on taper cutting have a strong agreement with the effects of ultra-precision machining tools, thus proving the stability and reliability of the integrated platform. The two-dimensional image measurement results show that the proposed measurement method is accurate and feasible. Finally, microstructure arrays were fabricated on the integrated platform as a typical case of a high-precision application.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

scholarly journals The two-dimensional hydrodynamical theory of moving aerofoils. IV

1947 ◽  
Vol 188 (1015) ◽  
pp. 439-463
Keyword(s):  
Stability Problem ◽  
Two Dimensional ◽  
Centre Of Gravity ◽  
First Approximation ◽  
Von Karman ◽  
Moving Cylinder ◽  
Period Equation ◽  
The Stability ◽  
Von Kármán ◽  
Hydrodynamical Theory

In the first part of this paper opportunity has been taken to make some adjustments in certain general formulae of previous papers, the necessity for which appeared in discussions with other workers on this subject. The general results thus amended are then applied to a general discussion of the stability problem including the effect of the trailing wake which was deliberately excluded in the previous paper. The general conclusion is that to a first approximation the wake, as usually assumed, has little or no effect on the reality of the roots of the period equation, but that it may introduce instability of the oscillations, if the centre of gravity of the element is not sufficiently far forward. During the discussion contact is made with certain partial results recently obtained by von Karman and Sears, which are shown to be particular cases of the general formulae. An Appendix is also added containing certain results on the motion of a vortex behind a moving cylinder, which were obtained to justify certain of the assumptions underlying the trail theory.

scholarly journals A thin, deformable, high-performance supercapacitor implant that can be biodegraded and bioabsorbed within an animal body

2021 ◽  
Vol 7 (2) ◽  
pp. eabe3097
Author(s):  
Hongwei Sheng ◽  
Jingjing Zhou ◽  
Bo Li ◽  
Yuhang He ◽  
Xuetao Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Electronic Devices ◽  
Form Factors ◽  
Time Frame ◽  
Water Soluble ◽  
Two Dimensional ◽  
Medical Electronics ◽  
Thin Structure ◽  
Shed Light

It has been an outstanding challenge to achieve implantable energy modules that are mechanically soft (compatible with soft organs and tissues), have compact form factors, and are biodegradable (present for a desired time frame to power biodegradable, implantable medical electronics). Here, we present a fully biodegradable and bioabsorbable high-performance supercapacitor implant, which is lightweight and has a thin structure, mechanical flexibility, tunable degradation duration, and biocompatibility. The supercapacitor with a high areal capacitance (112.5 mF cm−2 at 1 mA cm−2) and energy density (15.64 μWh cm−2) uses two-dimensional, amorphous molybdenum oxide (MoOx) flakes as electrodes, which are grown in situ on water-soluble Mo foil using a green electrochemical strategy. Biodegradation behaviors and biocompatibility of the associated materials and the supercapacitor implant are systematically studied. Demonstrations of a supercapacitor implant that powers several electronic devices and that is completely degraded after implantation and absorbed in rat body shed light on its potential uses.

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