scholarly journals Porous Gold Films Fabricated by Wet-Chemistry Processes

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Aymeric Pastre ◽  
Odile Cristini ◽  
Alexandre Boe ◽  
Katarzyna Raulin ◽  
Bertrand Grimbert ◽  
...  
Keyword(s):  
Electroless Deposition ◽  
Film Growth ◽  
Gold Film ◽  
Dip Coating ◽  
Gold Films ◽  
Covalent Bonds ◽  
Wet Chemistry ◽  
Porous Gold ◽  
Wide Range ◽  
20 Nm

Porous gold films presented in this paper are formed by combining gold electroless deposition and polystyrene beads templating methods. This original approach allows the formation of conductive films (2 × 106 (Ω·cm)−1) with tailored and interconnected porosity. The porous gold film was deposited up to 1.2 μm on the silicon substrate without delamination. An original zirconia gel matrix containing gold nanoparticles deposited on the substrate acts both as an adhesion layer through the creation of covalent bonds and as a seed layer for the metallic gold film growth. Dip-coating parameters and gold electroless deposition kinetics have been optimized in order to create a three-dimensional network of 20 nm wide pores separated by 20 nm thick continuous gold layers. The resulting porous gold films were characterized by GIXRD, SEM, krypton adsorption-desorption, and 4-point probes method. The process is adaptable to different pore sizes and based on wet-chemistry. Consequently, the porous gold films presented in this paper can be used in a wide range of applications such as sensing, catalysis, optics, or electronics.

On-Line Spectroscopic Characterization of Sodium Cyanide with Nanostructured Gold Surface-Enhanced Raman Spectroscopy Substrates

2002 ◽  
Vol 56 (12) ◽  
pp. 1524-1530 ◽  
Author(s):  
Peter M. Tessier ◽  
Steven D. Christesen ◽  
Kate K. Ong ◽  
Eva M. Clemente ◽  
Abraham M. Lenhoff ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sodium Cyanide ◽  
Raman Signal ◽  
Gold Films ◽  
Porous Gold ◽  
Wide Range ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
On Line

To implement surface-enhanced Raman spectroscopy as a practical detection method, highly enhancing, stable, and reproducible substrates need to be fabricated in an efficient manner, and their performance in different solution environments should be well characterized. In this work structured porous gold films have been fabricated using colloidal crystals to template gold nanoparticles. These films were integrated into an on-line flow chamber and used to study the effects of pH and other additives on the detection of sodium cyanide. The gold films proved to be highly enhancing and were used to detect cyanide over a wide range of pH values in the concentration range of ∼2 to 200 ppb. The Raman signal intensity could be increased by lowering the pH after the adsorption of cyanide, which was likely due to both a change in the ionization state and a conformational change of the bound molecules. The peak intensity could also be enhanced multifold by treating the substrate with silver nitrate. Cyanide could be removed from the substrates using hydrochloric acid, although this also passivated the structures, and the activity could only be restored partially with tannic acid. These results provide a rational method to optimize the online detection of cyanide in water.

Preparation and Characterization of Antibacterial Cap-Shaped Gold Nanoparticles

2012 ◽  
Vol 459 ◽  
pp. 360-363
Author(s):  
Yu Shan Xie ◽  
Shi Qing Man ◽  
Shao Zao Tan
Keyword(s):  
Antibacterial Activity ◽  
Gold Film ◽  
Self Assembled Monolayers ◽  
Gold Films ◽  
High Antibacterial Activity ◽  
Assembled Monolayers ◽  
Cubic Structure ◽  
Self Assembled ◽  
20 Nm

Gold nanocaps were prepared by vacuum depositing gold films onto self-assembled monolayers of SiO2nanoparticles, and characterized using SEM, AFM and XRD. Its antibacterial activity was investigated. It was found that gold films with cubic structure have completely covered self-assembled monolayers of SiO2nanoparticles. The gold nanocap, comprising of 20 nm gold film and 450 nm SiO2nanoparticles, possesses high antibacterial activity.

Electron-Phonon Non-Equilibrium in Nanoscale Gold Films

2008 ◽  
Author(s):  
Arvind Pattamatta ◽  
Cyrus K. Madnia
Keyword(s):  
Film Thickness ◽  
Pulse Duration ◽  
Laser Fluence ◽  
Laser Heating ◽  
Gold Film ◽  
Melting Time ◽  
Gold Films ◽  
Energy Carriers ◽  
Wide Range ◽  
Non Equilibrium

Ultrashort-pulsed laser irradiation on metals creates a thermal non-equilibrium between electrons and the phonons. Previous computational studies used the two-temperature model and its variants to model this non-equilibrium. However, when the laser pulse duration is smaller than the relaxation time of the energy carriers or when the carriers mean free path is larger than the material dimension, these macroscopic models fail to capture the physics accurately. In this paper, the non-equilibrium between energy carriers is modeled via numerical solution of the Boltzmann Transport Model (BTM) for electrons and phonons which is applicable over a wide range of length and time scales. The BTM is solved using the Discontinuous Galerkin Finite Element Method for spatial discretization and the three-step Runge Kutta temporal discretization. Temperature dependant electron-phonon coupling factor and electron heat capacity are used due to the strong electron-phonon non-equilibrium considered in this study. The results from the proposed model is compared with existing experimental studies on laser heating of macroscale materials. The model is then used to study laser heating of gold films, by varying parameters such as the film thickness, laser fluence and pulse duration. It is found that the temporal evolution of electron and phonon temperatures in nanometer size gold films are very different from the macroscale films. For a given laser fluence and pulse duration, the peak electron temperature increases with a decrease in the thickness of the gold film. Both film size as well as laser fluence significantly affect the melting time. For a fluence of 5000 J/m2, and a pulse duration of 75 fs, gold films of thickness smaller than 200 nm melt before reaching electron-phonon equilibrium. However, for the film thickness of 2000 nm, even with the highest laser fluence examined, the electrons and phonons reach equilibrium and the gold film does not melt.

Direct STEM ADF imaging of gold on silicon (111)

1989 ◽  
Vol 47 ◽  
pp. 472-473
Author(s):  
P. Xu ◽  
E. J. Kirkland ◽  
J. Silcox
Keyword(s):  
Film Growth ◽  
Heavy Atom ◽  
High Vacuum ◽  
Dark Field ◽  
Thin Metal Film ◽  
Base Pressure ◽  
Ultra High Vacuum ◽  
Specimen Preparation ◽  
Dark Field Imaging ◽  
Wide Range

Many studies of thin metal film growth and the formation of metal-semiconductor contacts have been performed using a wide range of experimental methods. STEM annular dark field imaging could be an important complement since it may allow direct imaging of a single heavy atom on a thin silicon substrate. This would enable studies of the local atomic arrangements and defects in the initial stage of metal silicide formation.Preliminary experiments were performed in an ultra-high vacuum VG HB501A STEM with a base pressure of 1 × 10-10 mbar. An antechamber directly attached to the microscope for specimen preparation has a base pressure of 2×l0-10 mbar. A thin single crystal membrane was fabricated by anodic etching and subsequent reactive etching. The specimen was cleaned by the Shiraki method and had a very thin oxide layer left on the surface. 5 Å of gold was deposited on the specimen at room temperature from a tungsten filament coil monitored by a quartz crystal monitor.

scholarly journals Surface Acoustic Wave Biosensor with Laser-Deposited Gold Layer Having Controlled Porosity

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 173
Author(s):  
Dana Miu ◽  
Izabela Constantinoiu ◽  
Valentina Dinca ◽  
Cristian Viespe
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Gold Film ◽  
Good Control ◽  
Gold Layer ◽  
Porous Gold ◽  
Deposition Parameters ◽  
Acoustic Wave Sensors ◽  
Controlled Porosity ◽  
Wave Sensors

Laser-deposited gold immobilization layers having different porosities were incorporated into love wave surface acoustic wave sensors (LW-SAWs). Variation of pulsed laser deposition parameters allows good control of the gold film morphology. Biosensors with various gold film porosities were tested using the biotin–avidin reaction. Control of the Au layer morphology is important since the biotin and avidin layer morphologies closely follow that of the gold. The response of the sensors to biotin/avidin, which is a good indicator of biosensor performance, is improved when the gold layer has increased porosity. Given the sizes of the proteins, the laser-deposited porous gold interfaces have optimal pore dimensions to ensure protein stability.

scholarly journals Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 785
Author(s):  
Chow Shing Shin ◽  
Yu Chia Chang
Keyword(s):  
High Resolution ◽  
Lattice Structure ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Dip Coating ◽  
Unit Cell ◽  
Digital Light Processing ◽  
Unit Cell Size ◽  
Wide Range ◽  
And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

Effect of the Dispersion of Nanosized Carbides (NbC - TaC) in the Sintered Microstructure of the Stainless Steel 316L

2008 ◽  
Vol 591-593 ◽  
pp. 294-298
Author(s):  
Uilame Umbelino Gomes ◽  
L.A. Oliveira ◽  
S.R.S. Soares ◽  
M. Furukava ◽  
C.P. Souza
Keyword(s):  
Stainless Steel ◽  
Automotive Industry ◽  
Sintering Temperature ◽  
Vacuum Furnace ◽  
Nanosized Particles ◽  
Stainless Steel 316L ◽  
Wide Range ◽  
Sintered Stainless Steel ◽  
20 Nm ◽  
Hardness Values

Sintered stainless steel has a wide range of applications mainly in the automotive industry. Properties such as wear resistance, density and hardness can be improved by addition of nanosized particles of refractory carbides. The present study compares the behavior of the sintering and hardness of stainless steel samples reinforced with NbC or TaC (particles size less than 20 nm) synthesized at UFRN. The main aim of this work was to identify the effect of the particle size and dispersion of different refractory carbides in the hardness and sintered microstructure. The samples were sintered in a vacuum furnace. The heating rate, sintering temperature and times were 20°C/min, 1290°C and 30, 60 min respectively. We have been able to produce compacts with a relative density among 95.0%. The hardness values obtained were 140 HV for the reinforced sample and 76 HV for the sample without reinforcement.

Aluminum nitride buffer layer for diamond film growth

1996 ◽  
Vol 11 (7) ◽  
pp. 1810-1818 ◽  
Author(s):  
V. P. Godbole ◽  
J. Narayan
Keyword(s):  
Aluminum Nitride ◽  
Buffer Layer ◽  
Diamond Film ◽  
High Speed ◽  
Film Growth ◽  
High Speed Steel ◽  
Bearing Steel ◽  
Low Carbon ◽  
Wide Range ◽  
Steel Substrates

The role of aluminum nitride (AlN) as a buffer layer on the nucleation and growth of diamond on silicon and steel substrates during hot filament chemical vapor deposition (HF-CVD) has been investigated systematically. The scanning Auger electron microscopy (AES) is employed to study chemistry and content of carbon on the surface and in subsurface regions of AlN as a function of HF-CVD parameters. It is found that AlN offers an excellent diffusion barrier for carbon over a wide range of temperature and hydrocarbon content of CVD gas environment, with simultaneous inhibition of graphitization. It also facilitates nucleation of diamond phase. The surface reactions between AlN and carbon are discussed in terms of hydrogen-assisted phase transformations. We have developed a two-step procedure to obtain a continuous diamond film on steel substrates. The characteristic features of AlN have been exploited to obtain adherent and graphite-free diamond deposits on various types of steels, including low carbon steel, tool steel, high speed steel, and bearing steel.

scholarly journals Simple Fabrication of Porous Gold-Film Electrodes and Their Electroanalytical Applications

2010 ◽  
Vol 26 (1) ◽  
pp. 129-132 ◽  
Author(s):  
Myeounghee HYUN ◽  
Suhee CHOI ◽  
Jongwon KIM
Keyword(s):  
Gold Film ◽  
Porous Gold ◽  
Porous Gold Film
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