Search results for "ALLOYS"
showing 10 items of 1689 documents
Aluminum oxide from trimethylaluminum and water by atomic layer deposition:The temperature dependence of residual stress, elastic modulus, hardness a…
2014
Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by na…
CLEASE: a versatile and user-friendly implementation of cluster expansion method
2018
Materials exhibiting a substitutional disorder such as multicomponent alloys and mixed metal oxides/oxyfluorides are of great importance in many scientific and technological sectors. Disordered materials constitute an overwhelmingly large configurational space, which makes it practically impossible to be explored manually using first-principles calculations such as density functional theory due to the high computational costs. Consequently, the use of methods such as cluster expansion (CE) is vital in enhancing our understanding of the disordered materials. CE dramatically reduces the computational cost by mapping the first-principles calculation results on to a Hamiltonian which is much fa…
Colloidal lithography and Metal-Organic Chemical Vapor Deposition process integration to fabricate ZnO nanohole arrays
2010
A complete set up of optimal process conditions for an effective colloidal lithography/catalyst assisted MOCVD process integration is presented. It mainly focuses on the determination of the deposition temperature threshold for ZnO Metal-Organic Chemical Vapour Deposition (MOCVD) as well as the concentration of metal-organic silver (Ag) catalyst. Indeed, the optimization of such process parameters allows to tailor the ZnO film morphology in order to make the colloidal lithography/catalyst assisted MOCVD approach a valuable bottom up method to fabricate bi-dimensional ordered ZnO nanohole arrays. (C) 2010 Elsevier B.V. All rights reserved.
Numerical model of macro-segregation during directional crystallization process
1998
Abstract In the paper the mathematical model of macro-segregation proceeding during the directional crystallization process is presented. The boundary-initial problem considered is discussed. Next the numerical approximation constructed on the basis of the boundary element method supplemented by a procedure called the artificial heat source method is described. The boundary condition on the solidification front resulting from the alloy component balance is introduced, while in finally the practical aspects of computations concerning the course of the process are discussed.
Large atomic disorder in nanostructured LaNi5 alloys: A la L3-edge extended X-ray absorption fine structure study
2010
Abstract Local structure of the nanostructured LaNi 5 alloys, prepared by ball-milling, has been studied using La L 3 -edge extended X-ray absorption fine structure spectroscopy. The near-neighbor distances tend to decrease with the ball-milling, and the mean square relative displacements (MSRD) show substantial increase suggesting an increased atomic disorder. High temperature annealing helps in partial recovery of atomic order in the ball-milled samples for milling times upto 20 h, however, the long-time ball-milled samples seems to gain only a local random order. The results suggest that reduced unit-cell volume together with large atomic-disorder might be causing a higher energy-barrier…
Tuning the magnetic properties in the layered molecular based magnets A[FeIIRuxIIIM1−xIII(ox)3] (MIII=Cr or Fe; ox=oxalate; A=organic or organometall…
2001
Abstract The magnetic properties of the family of layered molecular magnets A[FeIIMIII(ox)3] (MIII=Cr, Fe, Ru; ox=oxalate; A+=[NBu4]+, [ CoCp 2 ∗ ] + ) are reported. In particular, a detailed magnetic study of the solid solutions FeII(RuIIICrIII) and FeII(RuIIIFeIII) has been undertaken. We show that in these magnets both, transition temperatures and coercive fields, can be easily tuned by changing the chemical composition of the material, i.e. the ratio RuIII/MIII (MIII=Cr, Fe) within the magnetic layers and the type of cation A+ inserted in between the layers. Coercive fields as high as 2.2 T have been reached in this way.
Magnetic Langmuir–Blodgett films of ferritin with different iron loadings
2005
Abstract Magnetic Langmuir–Blodgett multilayers of two ferritin molecules 1 and 2 , containing, respectively, 4220 and 3062 Fe atoms have been prepared by using the adsorption properties of a 6/1 mixed monolayer of dioctadecyldimethylammonium bromide (DODABr) and methyl stearate (SME). Transfer ratios close to unity were reached giving rise to LB films with a strong red colour. Infrared and UV–vis spectroscopy indicates that ferritin molecules are incorporated within the LB films. Magnetic measurements show that the superparamagnetic properties of these molecules are preserved. Thus, a marked hysteresis loop of magnetisation is obtained for LB films of 1 and 2 with a coercive field of 3400 …
Oligo(phenylenevinylene)s with increased electron affinity: 1,3,4-oxadiazoles in the main chain
2001
Stilbenoid chromophores and 2,5-diaryl-1,3,4-oxadiazoles are compounds with wide technical importance. Their intense fluorescence is used in szintillators and optical whiteners and their semiconducting properties makes them valuable emissive or electron conducting layers in organic light emitting diodes (OLED). The synthesis and the electronic spectra of soluble oligo(phenylenevinylene)s with 1,3,4-oxadiazoles in the main chain are presented. The Huisgen reaction of tetrazole-terminated stilbenoid compounds with aromatic acyl chlorides yields model compounds, isophthalic acid dichlorides lead to soluble polymers with well-defined conjugated segments, as can be seen in the electronic spectra…
Inhibitoren der Korrosion (12). Nachweis der Bildung von Sekundärinhibitoren mit Hilfe der „Spezifischen Keim-Methode” von Karagounis
1972
Verschiedene gut inhibierende Oniumsalze werden in saurer Losung an der Oberflache von Eisen reduziert. Die dabei entstehenden Sekundarprodukte sind selbst gute Inhibitoren und bilden auf der Metalloberflache dunne Schichten. Diese haben unterschiedliche Dicke: Dibenzylsulfoxid bildet in kurzer Zeit bis zu 20 Molekullagen, einige quaternare Phosphoniumsalze im Laufe von 24 h nur ein bis zwei Molekullagen. Die Oberflachenbedeckung ist anfanglich nicht homogen. Die hier verwendete spezifische Kristallkeim-Methode von Karagounis bestatigt die analytischen Ergebnisse. Identification, by the “specific nucleus method according to Karagounis”, of the formation of secondary inhibitors Various onium…
Freeze-dried precursor-based synthesis of new polymetallic oxynitrides, V1−u−zCruMoz(OxNy),V1−u−zCruWz(OxNy), Cr1−u−zMouWz(OxNy) (u, z=0.2, 0.33, 0.4…
2005
Abstract Interstitial polymetallic oxynitrides in the solid solution series V 1− u − z Cr u Mo z (O x N y ), V 1− u − z Cr u W z (O x N y ) and Cr 1− u − z Mo u W z (O x N y ) ( u , z = 0.2, 0.33, 0.4, 0.6, u + z z Cr z Mo z W z (O x N y ) ( z = 0.25) composition, can be obtained by ammonolysis of precursors resulting from the freeze-drying of aqueous solutions of the simple metal salts NH 4 VO 3 , (NH 4 ) 2 CrO 4 , (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and (NH 4 ) 6 W 12 O 39 ·18H 2 O. A study of the influence of the preparative variables on the outcomes of this procedure is presented. Compounds in the V 1− u − z Cr u Mo z (O x N y ) series have been prepared as single phases by direct ammonolys…