Pulsed Laser Mixing of Metal Overlayers on Ceramics

1988 ◽  
Vol 100 ◽  
Author(s):  
R. K. Singh ◽  
N. Biunno ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Intense Laser ◽  
Interfacial Layers ◽  
Transmission Electron ◽  
Modification Technique ◽  
Mixed Layers ◽  
Metal Overlayers

ABSTRACTPulsed laser mixing has been used as surface modification technique for the improvement in the mechanical properties of ceramics. Thin metallic layers of nickel were deposited on structural silicon nitride and were irradiated with Xenon Chloride (XeCl) laser pulses. The laser parameters were optimized to lead to the formation of mixed layers. The mixed interfacial layers were analyzed using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Rutherford Backscattering (RBS) techniques. Detailed heat flow calculations were performed to simulate the effects of intense laser irradiation on metal coated ceramic structures. The melt lifetimes and the interfacial temperatures obtained using these calculations, were applied to understand the laser mixing phenomena occuring in these layered structures. Thermodynamics of chemical reactions between the metal overlayers and the substrate were done to predict the formation of mixed interfacial layers during laser irradiation.

Slim: a Personal Computer Based Software for Simulation of Laser Interaction with Materials

1991 ◽  
Vol 236 ◽  
Author(s):  
Rajiv K. Singh ◽  
John Viatella
Keyword(s):  
Laser Irradiation ◽  
Personal Computer ◽  
Rapid Heating ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Laser Interaction ◽  
History Of ◽  
Short Laser Pulses

AbstractA user-friendly, personal computer (PC) based routine called SLIM [Simulation of Laser Interaction with Materials] has been developed to understand the non-equilibrium effects of high intensity, short laser pulses on different materials. By employing an accurate implicit finite difference scheme with varying spatial and temporal node dimensions, the time-dependent thermal history of laser-irradiated material can be accurately and quickly determined. This program can take into account the temperature dependent optical and thermal properties of the solid, time dependent laser pulse intensity, and formation and propagation of the melt and/or vaporization interfaces induced by intense laser irradiation. The program can also simulate thermal effects on multilayer structures exposed to pulsed laser irradiation It is expected that this simulation routine will be indispensable to all researchers working in the area of pulsed laser processing of materials, including rapid heating, melting, annealing, laser doping, laser deposition of thin films and laser solidification processing.

Characterization of columns grown during KrF laser micromachining of Al2O3–TiC ceramics

2003 ◽  
Vol 18 (5) ◽  
pp. 1123-1130 ◽  
Author(s):  
V. Oliveira ◽  
R. Vilar
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Laser Pulses ◽  
Formation Mechanisms ◽  
X Ray ◽  
Reducing Conditions ◽  
Transmission Electron ◽  
Column Formation ◽  
Krf Laser

This paper aims to contribute to the understanding of column formation mechanisms in Al2O3–TiC ceramics micromachined using excimer lasers. Chemical and structural characterization of columns grown in Al2O3–TiC composite processed with 200 KrF laser pulses at 10 J/cm2 was carried out by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction analysis. Fully developed columns consist of a core of unprocessed material surrounded by an outer layer of Al2TiO5, formed in oxidizing conditions, and an inner layer, formed in reducing conditions, composed of TiC and Al3Ti or an AlTi solid solution. Possible mechanisms of column formation are discussed.

Laser assisted synthesis of WS2 nanorods by pulsed laser ablation in liquid environment

2021 ◽  
pp. 2140007
Author(s):  
Pankaj Koinkar ◽  
Kohei Sasaki ◽  
Tetsuro Katayama ◽  
Akihiro Furube ◽  
Satoshi Sugano
Keyword(s):  
Electron Microscopy ◽  
Laser Ablation ◽  
2D Materials ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Laser Ablation In Liquid ◽  
Simple Method ◽  
Liquid Environment ◽  
Transmission Electron ◽  
Specific Morphology

Two dimensional (2D) materials are widely attracting the interest of researchers due to their unique crystal structure and diverse properties. In the present work, tungsten disulfide (WS[Formula: see text] nanorods were synthesized by a simple method of pulsed laser ablation in liquid (PLAL) environment. The prepared WS2 are analyzed by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-visible spectroscopy (UV-vis) and Raman spectroscopy to confirm the surface morphology, phase and structure. A possible growth mechanism of WS2 is proposed. This study indicates new door for the preparation of 2D materials with specific morphology.

Atomic Structure and Property Correlation in Pulsed Laser Deposited High -Tc Films

1998 ◽  
Vol 526 ◽  
Author(s):  
R. Kalyanaraman ◽  
S. Oktyabrsky ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Structure And Property ◽  
Transmission Electron ◽  
Tilt Boundaries ◽  
Z Contrast

AbstractThe atomic structure of grain boundaries in pulsed laser deposited YBCO/MgO thin films have been studied using transmission electron microscopy. The films have perfect texturing with YBCO(001)//MgO(001), giving rise to low-angle [001] tilt boundaries from the grains with the c-axis normal to substrate surface. Low angle grain boundaries have been found to be aligned preferentially along (100) and (110) interface planes. The energy of (110) boundary planes described by an alternating array of [100] and [010] dislocation is found to be comparable to the energy of a (100) boundary. The existence of these split dislocations is shown to further reduce the theoretical current densities of these boundaries indicating that (110) boundaries carry less current as compared to (100) boundaries of the same misorientation angle. Further, Z-contrast transmission electron microscopy of a 42° asymmetric high-angle grain boundary of YBCO shows evidence for the existence of boundary fragments and a reduced atomic density along the boundary plane

Deposition of nitrides and oxides of aluminum and titanium by pulse laser irradiation

1992 ◽  
Vol 7 (3) ◽  
pp. 725-733 ◽  
Author(s):  
S.R. Nishitani ◽  
S. Yoshimura ◽  
H. Kawata ◽  
M. Yamaguchi
Keyword(s):  
Electron Microscopy ◽  
Laser Irradiation ◽  
Pulse Laser ◽  
Rutherford Backscattering Spectrometry ◽  
Metal Vapor ◽  
Pulse Laser Irradiation ◽  
X Ray ◽  
Transmission Electron ◽  
Ambient Gas ◽  
Scanning Electron

Deposits of nitrides and oxides of Al and Ti have been produced by laser irradiation of Al and Ti targets in air, N2, and NH3 + N2 gases. Microstructure and constituent phases in these deposits have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray diffractometry (XRD). The distribution of metalloid elements has been investigated by Rutherford backscattering spectrometry (RBS). On the basis of the results of these examinations, the nitride and oxide deposits have been shown to be formed by reactions between ambient gas and metal-melt or metal-vapor which take place during pulse laser irradiation.

Laser-Induced Oxidation and Crystallization of Thin Amorphous Sputtered Cr Films

1983 ◽  
Vol 29 ◽  
Author(s):  
M. I. Birjega ◽  
C. A. Constantin ◽  
M. Dinescu ◽  
I. Th. Florescu ◽  
I. N. Mihailescu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Laser Irradiation ◽  
Dwell Time ◽  
Free Standing ◽  
Transmission Electron Diffraction ◽  
Oxidation Processes ◽  
Transmission Electron ◽  
Power Densities

ABSTRACTThe crystallization and oxidation processes of thin, free-standing (FS), sputtered Cr films under the action of cw CO2 laser irradiation were studied by transmission electron microscopy (TEM) and transmission electron diffraction (TED). The crystallization is induced at power densities above 28.65 W cm−2, dwell time of 1 s, and the oxidation at power densities of 48.1 W cm−2 and longer dwell times.

Ion Beam, Rapid Thermal, and Laser Mixing Phenomena in Insulators

1985 ◽  
Vol 60 ◽  
Author(s):  
J. Narayan ◽  
B.R. Appleton
Keyword(s):  
Free Energy ◽  
Substrate Temperature ◽  
Laser Irradiation ◽  
Rapid Thermal Annealing ◽  
Ion Beam ◽  
Pulsed Laser ◽  
Beam Irradiation ◽  
Ion Beam Irradiation ◽  
Metal Overlayers ◽  
Pulsed Laser Irradiation

AbstractWe have studied mixing of metal overlayers (Ni, Cr, Ti, W, Ta, Zr, Cu) on insulators (SiC, Si3N4, Al2O3, SiO2) after ion beam irradiation, rapid thermal annealing, and pulsed laser irradiation. The nature and amount of mixing varies from stoichiometric to continuous, to ballistic, to no mixing at all. For a given system, the amount of mixing was found to increase with increasing substrate temperature. The enhanced mixing with increasing substrate temperature is correlated with concomitant free energy associated with the reactions. Certain systems such as Cu on Al2O3 do not exhibit mixing, but rearrangement within a few atomic layers at the interface results in enhanced adhesion and no aggregation upon annealing at moderate temperatures.

Time-Resolved X-Ray Studies During Pulsed-Laser Irradiation of Ge

1984 ◽  
Vol 35 ◽  
Author(s):  
J.Z. Tischler ◽  
B.C. Larson ◽  
D.M. Mills
Keyword(s):  
Melting Point ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
High Energy ◽  
Measured Temperature ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Pulsed Laser Irradiation

ABSTRACTSynchrotron x-ray pulses from the Cornell High Energy Synchrotron Source (CHESS) have been used to carry out nanosecond resolution measurements of the temperature distrubutions in Ge during UV pulsed-laser irradiation. KrF (249 nm) laser pulses of 25 ns FWHM with an energy density of 0.6 J/cm2 were used. The temperatures were determined from x-ray Bragg profile measurements of thermal expansion induced strain on <111> oriented Ge. The data indicate the presence of a liquid-solid interface near the melting point, and large (1500-4500°C/pm) temperature gradients in the solid; these Ge results are analagous to previous ones for Si. The measured temperature distributions are compared with those obtained from heat flow calculations, and the overheating and undercooling of the interface relative to the equilibrium melting point are discussed.

Encapsulated Fullerenes Within Single Wall Carbon Nanotubes

1999 ◽  
Vol 5 (S2) ◽  
pp. 182-183
Author(s):  
Brian W. Smith ◽  
David E. Luzzi
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Pulsed Laser ◽  
Irradiation Damage ◽  
Laser Vaporization ◽  
Single Wall Carbon Nanotubes ◽  
Phase Object ◽  
Parallel Lines ◽  
Weak Phase ◽  
Transmission Electron

It is well documented that the pulsed laser vaporization of graphite produces both carbon nanotubes and C60 in the presence of certain metallic catalysts. In nanotube production most of the Ceo is removed along with other residual contaminants during succeeding purification and annealing steps. The possibility of C60 becoming trapped inside a nanotube during this elaborate sequence has been considered but not previously detected.Nanotubes are observed with high resolution transmission electron microscopy under conditions chosen to minimize both exposure time and irradiation damage. Since a nanotube satisfies the weak phase object approximation, its image is a projection of the specimen -potential in the direction of the electron beam. The image has maximum contrast where the beam encounters the most carbon atoms, which occurs where it is tangent to the tube’s walls. Thus, the image consists of two dark parallel lines whose separation is equal to the tube diameter, 1.4 nm.

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