Excimer Laser Beam Interaction with Sintered Y2O3- Doped Aluminium Nitride Ceramic: Fundamentals and Appplication

1995 ◽  
Vol 397 ◽  
Author(s):  
N. Detournay ◽  
K. Kolev ◽  
T. Robert ◽  
M. Brunel ◽  
L.D. Laude
Keyword(s):  
Laser Beam ◽  
Excimer Laser ◽  
Metal Layer ◽  
Aluminium Nitride ◽  
X Ray Diffraction ◽  
Nickel Deposition ◽  
X Ray ◽  
High Electrical Resistivity ◽  
Excellent Adhesion ◽  
Induced Decomposition

ABSTRACTSintered aluminium nitride ceramic is most attractive for applications in modern electronic packaging, due to its high thermal conductivity and its high electrical resistivity. Among the sintering additives which are mentioned in the literature, Y2O3 is used most often as sintering accelerator and densificator for AlN commercial ceramics.Since excimer lasers have recently proved to be efficient in ceramic processing for industry, the effects of excimer laser irradiation on sintered Y2O3;rdoped AlN ceramic have been studied in this work. Raman spectroscopy, low-angle X-ray diffraction and scanning electron microscopy equipped with energy-dispersive X-ray analysis are used for characterizing both the initial and processed materials. The results reveal that yttrium-containing phases which are present at the AlN grain boundaries play an essential role in coupling the (λ =248nm) excimer laser beam with sintered material. Moreover, the laser-induced decomposition of these pre-existing complex phases and the subsequent spinel-like formation upon autocatalytic copper (or nickel) deposition are associated with (and explain) the excellent adhesion of the so-formed metal layer onto the ceramic substrate.

scholarly journals Thermal Effect of Ceramic Nanofiller Aluminium Nitride on Polyethylene Properties

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Omer Bin Sohail ◽  
P. A. Sreekumar ◽  
S. K. De ◽  
Masihullah Jabarullah Khan ◽  
Abbas Hakeem ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Filler Loading ◽  
Aluminium Nitride ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Nano Composite ◽  
X Ray ◽  
Thermal Gravimetric Analyzer

Ethylene polymerization was done to form polyethylene nano-composite with nanoaluminum nitride using zirconocene catalysts. Results show that the catalytic activity is maximum at a filler loading of 15 mg nanoaluminum nitride. Differential scanning calorimeter (DSC) and X-ray diffraction (XRD) results show that percentage crystallinity was also marginally higher at this amount of filler. Thermal behavior of polyethylene nanocomposites (0, 15, 30, and 45) mg was studied by DSC and thermal gravimetric analyzer (TGA). Morphology of the component with 15 mg aluminium nitride is more fibrous as compared to 0 mg aluminium nitride and higher filler loading as shown by SEM images. In order to understand combustibility behavior, tests were performed on microcalorimeter. Its results showed decrease in combustibility in polyethylene nanocomposites as the filler loading increases.

Laser-processing-induced phase transformation in Zn–Al-based alloy

1999 ◽  
Vol 14 (11) ◽  
pp. 4188-4194 ◽  
Author(s):  
Y. H. Zhu ◽  
J. A. Chavez-Carvayar ◽  
H. C. Man ◽  
M. Villagran
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Laser Beam ◽  
Phase Transformations ◽  
Laser Processing ◽  
Thermomechanical Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Backscattered Scanning Electron Microscopy ◽  
Scanning Electron

Microstructure and phase transformation of a furnace-cooled eutectoid Zn–Al-based alloy were studied after laser beam bombardment using low-angle x-ray diffraction (XRD) and backscattered scanning electron microscopy (BSEM). It was found that the microstructure of the laser-beam-treated specimen consisted mainly of the supersaturated Zn-rich β′s phase particulates of about 1−2 μm in diameter. Three structure morphologies were observed. Microcracking occurred in the laserbeam-affected zone during laser processing. Two laser-processing-induced phase transformations, i.e., decomposition of the η′FC phase and a four-phase transformation, were detected using XRD and BSEM techniques, similar to phase transformations that occurred in the same eutectoid Zn–Al-based alloy after various thermal and thermomechanical processing procedures.

scholarly journals Laser Mixing of Titanium on Silicon Carbide

1989 ◽  
Vol 157 ◽  
Author(s):  
T. R. Jervis ◽  
J-P. Hirvonen ◽  
M. Nastasi ◽  
M. R. Cohen
Keyword(s):  
Silicon Carbide ◽  
Excimer Laser ◽  
Laser Processing ◽  
Surface Region ◽  
Substrate Material ◽  
Laser Surface ◽  
X Ray Diffraction ◽  
Mixing Conditions ◽  
Surface Processing ◽  
X Ray

ABSTRACTWe have used excimer laser surface processing to melt and mix single Ti layers into the surface of polycrystalline SiC substrates. The mixing of Ti into the surface is very rapid and efficient. Examination of Rutherford backscattering (RBS) data for different mixing conditions shows the formation of a preferred composition at the Ti-substrate interface which propagates from the interface with further mixing. Reconstruction of the RBS spectrum indicates that the composition of the layer is Ti45C37Si18. X-ray diffraction demonstrates the formation of Ti suicides and carbides in the surface region. Profiling of C in both mixed and uncoated samples by 6 MeV He+ scattering demonstrates that laser processing of the SiC does not cause major changes in the stoichiometry of the substrate material.

Laser Induced Decomposition of Triethylgallium and Trimethylgallium Adsorbed on GaAs(100)

1988 ◽  
Vol 129 ◽  
Author(s):  
J. A. Mccaulley ◽  
V. R. Mccrary ◽  
V. M. Donnelly
Keyword(s):  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Electronic Excitation ◽  
Removal Rate ◽  
Laser Wavelength ◽  
High Fluence ◽  
X Ray ◽  
Two Photon ◽  
Induced Decomposition

ABSTRACTWe report X-ray photoelectron spectroscopy (XPS) studies of excimer laser stimulated decomposition of triethylgallium (TEGa) and trimethylgallium (TMGa) adsorbed on Gastabilized GaAs(100) surfaces in ultrahigh vacuum. TEGa and TMGa dissociatively chemisorb on GaAs at room temperature, whereupon irradiation by an excimer laser (at 193 or 351 nm) leads to further dissociation and desorption of carbon-containing species. The carbon removal rate (per laser pulse) decreases as carbon is removed suggesting multiple reaction sites, coverage dependent Arrhenius parameters, or second-order reactions. Based on the dependence of the rate on laser wavelength and fluence, we conclude that at low fluence, a two-photon electronic excitation of the adsorbate occurs, while at high fluence, laser induced pyrolysis dominates.

scholarly journals In Situ and Ex Situ Characterization of the Microstructure Formation in Ni-Cr-Si Alloys during Rapid Solidification—Toward Alloy Design for Laser Additive Manufacturing

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2192
Author(s):  
Xiaoshuang Li ◽  
Kai Zweiacker ◽  
Daniel Grolimund ◽  
Dario Ferreira Sanchez ◽  
Adriaan B. Spierings ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Laser Beam ◽  
Rapid Solidification ◽  
Liquid Droplet ◽  
Lamellar Microstructure ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray

Laser beam-based deposition methods such as laser cladding or additive manufacturing of metals promises improved properties, performance, and reliability of the materials and therefore rely heavily on understanding the relationship between chemical composition, rapid solidification processing conditions, and resulting microstructural features. In this work, the phase formation of four Ni-Cr-Si alloys was studied as a function of cooling rate and chemical composition using a liquid droplet rapid solidification technique. Post mortem x-ray diffraction, scanning electron microscopy, and in situ synchrotron microbeam X-ray diffraction shows the present and evolution of the rapidly solidified microstructures. Furthermore, the obtained results were compared to standard laser deposition tests. In situ microbeam diffraction revealed that due to rapid cooling and an increasing amount of Cr and Si, metastable high-temperature silicides remain in the final microstructure. Due to more sluggish interface kinetics of intermetallic compounds than that of disorder solid solution, an anomalous eutectic structure becomes dominant over the regular lamellar microstructure at high cooling rates. The rapid solidification experiments produced a microstructure similar to the one generated in laser coating thus confirming that this rapid solidification test allows a rapid pre-screening of alloys suitable for laser beam-based processing techniques.

KrF Excimer Laser Ablation of Human Enamel

2008 ◽  
Vol 587-588 ◽  
pp. 42-46 ◽  
Author(s):  
M. Sivakumar ◽  
Vitor Oliveira ◽  
Rui Vilar ◽  
A.M. Botelho do Rego
Keyword(s):  
Laser Treatment ◽  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Structural Water ◽  
X Ray ◽  
Human Enamel ◽  
Excimer Laser Radiation ◽  
Krf Excimer Laser ◽  
Dental Applications

Laser treatment is a promising technique for dental applications such as caries prevention, dental hypersensitivity reduction and improvement of bond strength of restoration materials. In this study the morphological, structural and chemical changes of enamel surface due to treatment with KrF excimer laser radiation were evaluated using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. For radiation fluences near 1 J/cm², laser processing originates a relatively porous surface due to preferential removal of material in the enamel prism sheaths. Increasing the fluence leads to a relatively flat surface with clear evidence of surface melting. The X-ray diffractograms of both treated and untreated enamel are similar and correspond to hydroxyapatite. The only modification due to the laser treatment is a slight shift of the peaks, probably, due to a loss of the structural water of hydroxyapatite. X-ray photoelectron spectroscopy confirmed that organic matter is removed from the irradiated surface but no significant changes in the mineral phase occur.

Excimer laser recrystallization of amorphous Si films characterized by grazing X-ray diffraction and optical reflectivity

1989 ◽  
Vol 43 (1-4) ◽  
pp. 142-149 ◽  
Author(s):  
E.L. Mathé ◽  
J.G. Maillou ◽  
A. Naudon ◽  
E. Fogarassy ◽  
M. Elliq ◽  
...  
Keyword(s):  
Excimer Laser ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optical Reflectivity ◽  
Laser Recrystallization ◽  
Amorphous Si ◽  
Si Films

XRD Characterization for Al- and N-Doped 3C-SiC on Si (100) Substrate after Pulsed Excimer Laser Anneal

2012 ◽  
Vol 717-720 ◽  
pp. 497-500
Author(s):  
Kung Yen Lee ◽  
Yan Hao Huang ◽  
Chih Fang Huang ◽  
Cheng Yueh Chung ◽  
Shun Chiu Lin ◽  
...  
Keyword(s):  
Energy Density ◽  
Total Energy ◽  
Excimer Laser ◽  
Peak Shift ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Laser Anneal

This paper characterizes Al, N doped and undoped 3C-SiC samples after pulsed excimer laser anneal by using X-ray diffraction (XRD) and atomic force microscopy (AFM). In order to protect surface morphology, low energy density of 0.2444 J/cm2 per shot was applied to Al and N doped samples. The results show damage recovery is corresponding to the amount of total energy applied to the surface. The peak shift of Bragg diffraction spectra of Al doped samples are almost independent of the amount of total energy. As the energy density is reduced to 0.0667 J/cm2 per shot and applied to undoped samples, the peaks of Bragg diffraction spectra of undoped samples are shifted. However, the peaks of Bragg diffraction spectra of undoped samples annealed with combination of energy densities of 0.0667 and 0.2444 J/cm2 are not shifted.

scholarly journals Reactive Mechanism of Cu2ZnSnSe4 Thin Films Prepared by Reactive Annealing of the Cu/Zn Metal Layer in a SnSex + Se Atmosphere

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 10 ◽  
Author(s):  
Liyong Yao ◽  
Jianping Ao ◽  
Ming-Jer Jeng ◽  
Jinlian Bi ◽  
Shoushuai Gao ◽  
...  
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Annealing Temperature ◽  
Metal Layer ◽  
Strong Dependence ◽  
Process Variations ◽  
Secondary Phase ◽  
Elemental Distribution ◽  
X Ray Diffraction ◽  
X Ray

Cu2ZnSnSe4 (CZTSe) thin films were prepared by a two-step process with the electrodeposition of a Cu/Zn metallic stack precursor followed by a reactive anneal under a Se + Sn containing atmosphere. We investigate the effect of the Sex and SnSex (x = 1,2) partial pressures and annealing temperature on the morphological, structural, and elemental distribution of the CZTSe thin films. Line scanning energy dispersive spectroscopy (EDS) measurements show the presence of a Zn-rich secondary phase at the back-absorber region of the CZTSe thin films processed with higher SnSex partial pressure and lower annealing temperatures. The Zn-rich phase can be reduced by lowering the SnSex partial pressure and by increasing the annealing temperature. A very thin MoSe2 film between the CZTSe and Mo interface is confirmed by X-ray diffraction (XRD) and grazing incidence X-ray diffraction (GIXRD) measurements. These measurements indicate a strong dependence of these process variations in secondary phase formation and accumulation. A possible reaction mechanism of CZTSe thin films was presented. In a preliminary optimization of both the SnSex partial pressure and the reactive annealing process, a solar cell with 7.26% efficiency has been fabricated.

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