LiNbO3 thin films were deposited by dip coating Li-Nb alkoxide solutions onto silicate glass substrates and single crystal sapphire substrates. Microstructural characterization using transmission electron microscopy (...
LiNbO3 thin films were deposited by dip coating Li-Nb alkoxide solutions onto silicate glass substrates and single crystal sapphire substrates. Microstructural characterization using transmission electron microscopy (TEM) showed significant differences in film microstructures dependent on the initial solution chemistry. Fully crystalline films could be obtained after heat treatments at 400°C in air. The grain size and porosity were dependent on the amount of water of hydrolysis in the alkoxide sol. The higher the water content, the larger the grain size and porosity. Crystallization studies of nucleation and growth of LiNbO3 for films heat treated from 300–600°C indicated that higher temperatures or long soak times generated large facetted grain structures. Single crystalline films were obtained on (0001) sapphire substrates.
The vacancy formation thermodynamics in six fcc metals Ag, Au, Cu, Ni, Pd and Pt are determined from atomistic simulations as a function of temperature. This investigation is performed using the Embedded Atom Method i...
The vacancy formation thermodynamics in six fcc metals Ag, Au, Cu, Ni, Pd and Pt are determined from atomistic simulations as a function of temperature. This investigation is performed using the Embedded Atom Method interatomic potentials and the finite temperature properties are determined within the local harmonic and the quasiharmonic frameworks. We find that the temperature dependence of the vacancy formation energy can make a significant contribution to the vacancy concentration at high temperatures. An additional goal of the present study is to evaluate the accuracy of the local harmonic method under circumstances in which the excess entropy associated with the formation of a defect is very small. Our data demonstrate that while the errors associated with determining the vacancy formation entropy in the local harmonic model are large, a simple extension to the local harmonic method yields thermodynamic properties comparable to that obtained in the quasiharmonic model, but with much higher computational efficiency.
Self-interstitial sink efficiencies of dislocations γ were measured in gold doped FZ (111) and (100) samples, we found respectively γ≈0.4–0.5 and γ≈0.2–0.3. γ is probably sensitive to dislocation character and...
Self-interstitial sink efficiencies of dislocations γ were measured in gold doped FZ (111) and (100) samples, we found respectively γ≈0.4–0.5 and γ≈0.2–0.3. γ is probably sensitive to dislocation character and to the deformation process.
Three Dimensional Printing is a process for rapid prototyping of functional components. Thin layers of powder are bound in selected areas by ink-jet printing of a liquid binder. Layers are added sequentially until a t...
Three Dimensional Printing is a process for rapid prototyping of functional components. Thin layers of powder are bound in selected areas by ink-jet printing of a liquid binder. Layers are added sequentially until a three dimensional part is completed. The unbound powder is then removed. The raster scan pattern and layering used in forming has an observable effect on the surface finish and microstructure of the part, as does the chemistry of the particular materials system used. Important phenomena include ballistic interaction of the jet with the powder bed and wicking of the binder. Process parameters such as layer height, flow rate, and powder density were studied. Microstructural examination of the printed components is also reported.
Lithium niobate prepared by sol-gel techniques can crystallize at temperatures as low as 200°C, and achieve a high homogeneity. In this sutdy, nucleation, crystallization, and morphological development are examin...
Lithium niobate prepared by sol-gel techniques can crystallize at temperatures as low as 200°C, and achieve a high homogeneity. In this sutdy, nucleation, crystallization, and morphological development are examined by TEM for alkoxide derived LiNbO3. Preliminary studies show that the as-dried gel is completely amorphous and homogeneous. Between 150-200°C, crystallization begins with crystallites on the order of 10-20 nm appearing in the amorphous matrix. By 450°C, single crystal spheroidal particles (0.05–0.2 μm) form. By 600°C, facetted large crystallites on the order of 1 gtm develop. Grain size and porosity are strongly dependent on the amount of water of hydrolysis in thin films.
The central solenoids for the Burning Plasma Experiment will experience a thermal and mechanical cyclic loading. A series of tensile, fatigue, crack growth, resistivity and joint component tests are currently underway...
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A recently developed method for producing triaxial alignment of single crystalline grains may be applicable to ceramics other than the high-Tc cuprate superconductors for which it was designed as a means of reducing t...
A recently developed method for producing triaxial alignment of single crystalline grains may be applicable to ceramics other than the high-Tc cuprate superconductors for which it was designed as a means of reducing the grain boundary weak links due to grain orientational misfit. This technique uses a suitable combination of a mechanical force and a magnetic field acting on the moment of a rare earth element incorporated into the ceramic; a “granular single crystal” is thus formed. A detailed step-by-step procedure is presented here to facilitate use of the new approach.
As known to all,shape memory behaviour has been observed in a variety of metallic alloys. This phenomenon, however, is not only observed in that field but also in other materials recently, such as in polymers, inter-m...
As known to all,shape memory behaviour has been observed in a variety of metallic alloys. This phenomenon, however, is not only observed in that field but also in other materials recently, such as in polymers, inter-metallic compounds and ceramics, especially in zirconia ceramics. Swain [1] observed the shape recovery of a bent magnesia-partially-stabilized zirconia (Mg-PSZ) bar upon heating above a certain temperature. The maximum deflection which was nearly completely recovered on heating is about 300 μm. Chen et al [2] investigated the pseudoelasticity and shape memory effect (SME) in ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP) containing 12 mol% CeO2. Wang et al [3] also observed the SME in Ce-TZP containing 10 mol% CeO2. Here we would like to introduce some of results conducted recently in our group on SME in Ce-TZP ceramics.
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