Structural Control of Hybrid Colloidal Particle Surface by Plasma-etching Treatment

2016 ◽  
Vol 45 (8) ◽  
pp. 979-981 ◽  
Author(s):  
Akira Ohnuma ◽  
Hiroki Yamamoto ◽  
Takahiro Kozawa ◽  
Bunsho Ohtani
Keyword(s):  
Plasma Etching ◽  
Structural Control ◽  
Colloidal Particle ◽  
Particle Surface

Analysis and Application of Oxalic Acid Modified Sodium Silicate Binder

2012 ◽  
Vol 573-574 ◽  
pp. 31-34
Author(s):  
Li Ge Wang ◽  
Fan Zhang ◽  
Yang Zhang ◽  
Long Zhou ◽  
En Ze Wang
Keyword(s):  
Compressive Strength ◽  
Oxalic Acid ◽  
Chemical Modification ◽  
Functional Groups ◽  
Sodium Silicate ◽  
Bonding Strength ◽  
Colloidal Particle ◽  
Particle Surface ◽  
Growing Up ◽  
New Type

A new type of pellet binder was prepared with oxalic acid as sodium silicate chemical modification agent in this paper, the compressive strength of which improved obviously. It improved from 0.6 KN/a to 2.4 KN/a, when the amount of oxalic acid is 8%. Meanwhile, carboxyl introduced at 390°C started carbonization decomposition, and pelletizing properties wouldn't be affected without new pellet impurity. The analysis shows that adding oxalic acid introduces carboxyl only in the binder, but doesn't generate new functional groups; Polymer layer formed by carboxyl adsorption on sodium silicate gel particle surface limits colloidal particle growing up, and plays roles of refining colloidal particle and improving the bonding strength.

Electrohydrodynamic flow around a colloidal particle near an electrode with an oscillating potential

2007 ◽  
Vol 575 ◽  
pp. 83-109 ◽  
Author(s):  
W. D. RISTENPART ◽  
I. A. AKSAY ◽  
D. A. SAVILLE
Keyword(s):  
Long Range ◽  
Electric Fields ◽  
Peclet Number ◽  
Colloidal Particle ◽  
Particle Surface ◽  
Axisymmetric Flow ◽  
Thin Layers ◽  
Double Layers ◽  
Péclet Number ◽  
Wide Range

Electrohydrodynamic (EHD) flow around a charged spherical colloid near an electrode was studied theoretically and experimentally to understand the nature of long-range particle–particle attraction near electrodes. Numerical computations for finite double-layer thicknesses confirmed the validity of an asymptotic methodology for thin layers. Then the electric potential around the particle was computed analytically in the limit of zero Péclet number and thin double layers for oscillatory electric fields at frequencies where Faradaic reactions are negligible. Streamfunctions for the steady component of the EHD flow were determined with an electro-osmotic slip boundary condition on the electrode surface. Accordingly, it was established how the axisymmetric flow along the electrode is related to the dipole coefficient of the colloidal particle. Under certain conditions, the flow is directed toward the particle and decays as r−4, in accord with observations of long-range particle aggregation. To test the theory, particle-tracking experiments were performed with fluorescent 300 nm particles around 50μm particles over a wide range of electric field strengths and frequencies. Treating the particle surface conductivity as a fitting parameter yields velocities in excellent agreement with the theoretical predictions. The observed frequency dependence, however, differs from the model predictions, suggesting that the effect of convection on the charge distribution is not negligible as assumed in the zero Péclet number limit.

Defects Around a Spherical Particle in Cholesteric Liquid Crystals

2017 ◽  
Vol 10 (2) ◽  
pp. 205-221 ◽  
Author(s):  
Yu Tong ◽  
Yiwei Wang ◽  
Pingwen Zhang
Keyword(s):  
Particle Size ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Coherence Length ◽  
Colloidal Particle ◽  
Cholesteric Liquid Crystal ◽  
Particle Surface ◽  
Defect Structures ◽  
Spherical Colloidal Particle ◽  
Metastable Defect

AbstractWe investigate the defect structures around a spherical colloidal particle in a cholesteric liquid crystal using spectral method, which is specially devised to cope with the inhomogeneity of the cholesteric at infinity. We pay particular attention to the cholesteric counterparts of nematic metastable configurations. When the spherical colloidal particle imposes strong homeotropic anchoring on its surface, besides the well-known twisted Saturn ring, we find another metastable defect configuration, which corresponds to the dipole in a nematic, without outside confinement. This configuration is energetically preferable to the twisted Saturn ring when the particle size is large compared to the nematic coherence length and small compared to the cholesteric pitch. When the colloidal particle imposes strong planar anchoring, we find the cholesteric twist can result in a split of the defect core on the particle surface similar to that found in a nematic liquid crystal by lowering temperature or increasing particle size.

Biomimetic materials: An introduction

1992 ◽  
Vol 50 (2) ◽  
pp. 1020-1021 ◽  
Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay
Keyword(s):  
Self Assembly ◽  
Structural Control ◽  
Hierarchical Structures ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Length Scale ◽  
Spider Webs ◽  
Biomimetic Materials ◽  
Synthetic Materials ◽  
All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

Using the secondary electrons (SE) of SEM with NIST‘s MONSEL-II program to obtain improved linewidth measurements and slope angles of line edges on a MMIC GaAs device

1996 ◽  
Vol 54 ◽  
pp. 944-945
Author(s):  
Richard G. Sartore
Keyword(s):  
Integrated Circuits ◽  
Plasma Etching ◽  
Microwave Integrated Circuits ◽  
Monolithic Microwave Integrated Circuits ◽  
Thick Gold ◽  
Gaas Devices ◽  
Source Distance ◽  
Margin Of Error ◽  
Dimensional Measurements ◽  
Barrier Metal

In the evaluation of GaAs devices from the MMIC (Monolithic Microwave Integrated Circuits) program for Army applications, there was a requirement to obtain accurate linewidth measurements on the nominal 0.5 micrometer gate lengths used to fabricate these devices. Preliminary measurements indicated a significant variation (typically 10 % to 30% but could be more) in the critical dimensional measurements of the gate length, gate to source distance and gate to drain distance. Passivation introduced a margin of error, which was removed by plasma etching. Additionally, the high aspect ratio (4-5) of the thick gold (Au) conductors also introduced measurement difficulties. The final measurements were performed after the thick gold conductor was removed and only the barrier metal remained, which was approximately 250 nanometer thick platinum on GaAs substrate. The thickness was measured using the penetration voltage method. Linescan of the secondary electron signal as it scans across the gate is shown in Figure 1.

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