Stabilization, Characterization and Optical Applications of Niobium and Tantalum Oxide Sols Prepared Via Alkoxide Routes

1990 ◽  
Vol 180 ◽  
Author(s):  
Stephen Parraud ◽  
Liliane G. Hubert-Pfalzgraf ◽  
Herve Floch
Keyword(s):  
Spin Coating ◽  
Tantalum Oxide ◽  
Pulse Length ◽  
Single Layer ◽  
Colloidal Suspensions ◽  
Laser Damage ◽  
Threshold Values ◽  
Small Particles ◽  
Optical Applications ◽  
Hydrolysis Of

ABSTRACTHydrolysis of niobium and tantalum pentaethoxides in ethanol and in the presence of basic (ammonia, tetramethylammonium hydroxide, di and triethylamine) or acidic (nitric or hydrochloric acids) additives was investigated. Triethylamine gives monodispersed, small particles of amorphous M2O5,nH2O (M = Nb, Ta). These colloidal suspensions were used to obtain thin films by spin-coating techniques. The coatings display a thickness of 100–300 nm and a refractive index around 1.7. Laser damage tests at 1064 nm wavelength with a pulse length of 3 ns were carried out on the single layer systems. The threshold values (one-onone) are in favor of the Ta2O5 coatings with an average of 14.5 ± 2.1 J/cm2 , by comparison with 8.3 ± 1.6 J/cm2 for the Nb2O5 films.

Buckling of a Confined Colloidal Crystal

1992 ◽  
Vol 290 ◽  
Author(s):  
T. Chou ◽  
D. R. Nelson
Keyword(s):  
Colloidal Crystal ◽  
Single Layer ◽  
Colloidal Suspensions ◽  
Plate Separation

AbstractThe behavior of colloidal suspensions confined between two plates narrowly spaced is examined. When plate separations are small, only one layer of particles can be confined; however, as plate separation is increased, multiple layers will eventually form. These layers can exist in a variety of structures depending on the energetics of packing. We examine the unstable modes which form as a single layer buckles on its way to forming two layers. Three ordered states are found; which one is selected depends on the form of the interparticle and wall potentials.

Hydrolysis of Methoxylated Nickel Hydroxide Leading to Single-Layer Ni(OH)2 Nanosheets

2021 ◽  
Author(s):  
Keisuke Muramatsu ◽  
Yoshiyuki Kuroda ◽  
Hiroaki Wada ◽  
Atsushi Shimojima ◽  
Kazuyuki Kuroda
Keyword(s):  
Nickel Hydroxide ◽  
Single Layer ◽  
Hydrolysis Of

Formation of hybrid colloids by suspension polycondensation in the presence of hydrophilic block copolymers

2002 ◽  
Vol 726 ◽  
Author(s):  
Corine Gerardin ◽  
Valérie Buissette ◽  
François Gaudemet ◽  
Olivier Anthony ◽  
Nicolas Sanson ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Colloidal Suspensions ◽  
Surface Charges ◽  
Inorganic Particles ◽  
Hydrous Oxides ◽  
Stabilization Phase ◽  
Metal Ratio ◽  
Forced Hydrolysis ◽  
Hydrolysis Of

AbstractDouble hydrophilic block copolymers were used to control the growth of inorganic particles and directly prepare hybrid colloidal suspensions. Colloids of metal hydrous oxides were obtained by forced hydrolysis of metal ions in presence of the copolymers. The block copolymers contain a metal-complexing polyelectrolyte block and a stabilizing neutral block. The role of the first block is to ensure a controlled growth of the inorganic phase, while simultaneously, the second block ensures the colloidal stabilization. Phase diagrams presenting the conditions under which precipitation is inhibited are established. The nanoparticles are then characterized in terms of sizes, morphologies and surface charges. The main parameters controlling the size were identified: the copolymer-to-metal ratio and the metal prehydrolysis ratio. The synthesis steps were characterized. First, a key step of induced micellization of the hydrophilic copolymers leads to hybrid core-shell assemblies. The second step consists in mineralization of the micellar core. The suspension polycondensation leads to hairy particles whose morphologies depend on the nature of the metal and on synthesis parameters.

Tuning band gap and optical properties of SnX2 nanosheets: Hybrid functional studies

2016 ◽  
Vol 30 (10) ◽  
pp. 1650120 ◽  
Author(s):  
P. Guo ◽  
Y. W. Luo ◽  
Y. Jia
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Band Gap ◽  
Electronic Structures ◽  
Threshold Values ◽  
Hybrid Functional ◽  
Functional Studies ◽  
Quantum Size ◽  
Light Activity ◽  
Optical Applications

Based on hybrid functional calculations, the electronic structures and optical properties are investigated in the monolayer and bilayer tin dichalcogenides SnX2 (X = S and Se) nanosheets. Numerical results show that quantum size effects are obvious on the electronic structures and optical absorption in the SnS2 and SnSe2 nanosheets. The band gap values increase when the nanosheets layer numbers decrease. Moreover, for SnSe2 nanosheet, the optical absorption coefficients are high and its threshold values lie in the visible light activity range. These results are interesting and indicate that SnS2 and SnSe2 nanosheets may serve as the promising candidates for visible optical applications.

Fabrication of polyimide films with imaging quality using a spin-coating method for potential optical applications

2019 ◽  
Vol 39 (10) ◽  
pp. 917-925 ◽  
Author(s):  
Danbo Mao ◽  
Gang Lv ◽  
Guohan Gao ◽  
Bin Fan
Keyword(s):  
Film Thickness ◽  
Spin Coating ◽  
Empirical Relationship ◽  
Optical Quality ◽  
Optimum Process ◽  
Fluid Viscosity ◽  
Factors Affecting ◽  
Imaging Quality ◽  
Rotating Speed ◽  
Optical Applications

Abstract Optical polyimide (PI) films were prepared by spin-coating from nearly non-volatile dimethylacetamide (DMAc) solutions. The uniformity of film thickness met the requirements of diffraction imaging quality. The results show that the final rotating speed ω, dynamic viscosity η, and initial polymer solid concentration c are the main factors affecting the film thickness T, and an empirical relationship which describes the film thickness as a function of the measured parameters was established to be $T \propto {c^{3.473}},{\rm{ }}{\eta ^{0.586}},{\rm{ }}{\omega ^{ - 0.811}}.$ Moreover, the viscosity dependence on concentration is system specific. Unlike traditional photoresist, the thickness uniformity of the PI film is determined by both spinning and precure process, which is intensively discussed in the present work. Uniform, 22-μm thick, PI films with transmitted wavefronts peak to valley (PV) ≤ 1/5 λ and root mean square (RMS) ≤ 1/50 λ were prepared under the optimum process: spin speed 900 rpm, initial fluid viscosity 10,500 cp, final spin time 120 s, precure temperature 70°C, spin process repeated 3 times. The results will find use in the production of optical quality membrane for ultra-lightweight optics or other applications.

scholarly journals Characterization and photocatalytic study of tantalum oxide nanoparticles prepared by the hydrolysis of tantalum oxo-ethoxide Ta8(μ3-O)2(μ-O)8(μ-OEt)6(OEt)14

2014 ◽  
Vol 5 ◽  
pp. 1082-1090 ◽  
Author(s):  
Subia Ambreen ◽  
N D Pandey ◽  
Peter Mayer ◽  
Ashutosh Pandey
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Tantalum Oxide ◽  
Organic Dye ◽  
Oxide Nanoparticles ◽  
Tauc Plot ◽  
Particle Size Analyzer ◽  
Bet Method ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

Ta8(μ3-O)2(μ-O)8(μ-OEt)6(OEt)14 (1) was obtained by the controlled hydrolysis of tantalum ethoxide Ta(OEt)5 in the presence of ammonia. Compound 1 is considered as the intermediate building block in the sol–gel polymerization of Ta(OEt)5. Further hydrolysis of compound 1 yielded nanoparticles of Ta2O5, which were characterized by various techniques such as TGA-DTA-DSC, UV–vis DRS, XRD, SEM, TEM, particle size analyzer (DLS) and the Brunauer–Emmett–Teller (BET) method. The band gap of the particles was calculated by using the Tauc plot. The photocatalytic activity of Ta2O5 nanoparticles was tested by the degradation of the organic dye rhodamine B.

Operational Characteristics of GaSe Crystals for Mid-IR and Far-IR Applications

1997 ◽  
Vol 484 ◽  
Author(s):  
N. C. Fernelius ◽  
F. K. Hopkins ◽  
N. B. Singh ◽  
D. Suhre ◽  
M. Marable ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Laser Damage ◽  
Phase Matching ◽  
Bridgman Technique ◽  
Operational Characteristics ◽  
Optical Applications ◽  
Nonlinear Optical Applications ◽  
Good Agreement

AbstractGaSe has a number of attractive properties for nonlinear optical applications including large birefringence for ease in phase matching. Its biggest drawback is its mechanical properties. GaSe has a strong tendency to cleave along the <100> plane which has made it difficult to grow and fabricate. We have developed a method to modify GaSe by structurally strengthening the material by doping. We have synthesized large boules of GaSe reacted mixtures and grown centimeter size single crystals by the Bridgman technique. Depending on the dopant and crystal quality, SHG measurements indicate a deff, of 51 to 76 pm/V. SHG power levels were theoretically calculated and appear to be in good agreement with the experimental data. The measured performance of crystals for the fourth harmonic generation and laser damage threshold are also reported in this paper. The damage threshold was greater than 2.8 J/cm2 and 85 KW/cm2 at the surface of the crystal.

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