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Shibata, Shuichi; Miyajima, Katsuya; Yoshikawa, Hidemi; Yano, Tetsuji; Yamane, M.

doi:10.1023/a:1008798302971

Cited by 5 publications

(2 citation statements)

References 5 publications

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“…The spontaneous pattern formation induced by Bénard–Marangoni convection can be also found on sol–gel-derived inorganic and organic–inorganic hybrid films. − The thickness variations of sol–gel coating films are reported to be caused by the Bénard–Marangoni convection. ,, In the case of polymer films, the solvent depletion from the surface of the coating layer often creates solute-rich skins, providing the local surface tension gradient . Birnie et al investigated the thickness variations in sol–gel-derived spin-coating films and suggested that the surface tension gradient as a result of the solute-rich skins leads to the lateral flow of solutions toward the higher surface tension area (i.e., solute-rich area) and then the skins become thicker with time, resulting in surface roughening .…”

Section: Introductionmentioning

confidence: 99%

Spontaneous Pattern Formation Induced by Bénard–Marangoni Convection for Sol–Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility

2015

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Evaporation-driven surface tension gradient in the liquid layer often causes the convective flow, i.e., Bénard-Marangoni convection, resulting in the formation of cell-like patterns on the surface. Here, we prepared sol-gel-derived titania films from Ti(OC3H7(i))4 solutions by dip coating and discussed the effect of the addition of co-solvents with a high surface tension and low volatility on the spontaneous pattern formation induced by Bénard-Marangoni convection. Propylene glycol (PG, with a surface tension of 38.6 mN m(-1)) and dipropylene glycol (DPG, with a surface tension of 33.9 mN m(-1)) were added to the coating solutions containing 2-propanol (2-Pr, with a surface tension of 22.9 mN m(-1)) for controlling the evaporation-driven surface tension gradient in the coating layer on a substrate. During dip coating at a substrate withdrawal speed of 50 cm min(-1) in a thermostatic oven at 60 °C, linearly arranged cell-like patterns on a micrometer scale were spontaneously formed on the titania gel films, irrespective of the composition of coating solutions. Such surface patterns remained even after the heat treatment at 200 and 600 °C, where the densification and crystallization of the titania films progressed. The width and height of the cell-like patterns increased with increasing PG and DPG contents in the coating solutions, where the addition of PG resulted in the formation of cells with a larger height than DPG.

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Section: Introductionmentioning

confidence: 99%

Spontaneous Pattern Formation Induced by Bénard–Marangoni Convection for Sol–Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility

2015

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“…Sol-gel coating processes are widely used for preparing inorganic and organic-inorganic hybrid films, where micrometersized patterns such as unevenness in thickness or ridges are formed on the surface of the films under certain conditions. [22][23][24][25][26][27][28][29][30][31] We previously prepared sol-gel-derived silica and titania dipcoating films at extremely low substrate withdrawal speeds below 1.0 cm min À1 , and found the spontaneous formation of stripe patterns based on the ''coffee-ring effect'' during the dipcoating. 29 The stripe patterns were arranged perpendicular to the withdrawal direction, and the height and width increased with decreasing withdrawal speeds.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous pattern formation based on the coffee-ring effect for organic–inorganic hybrid films prepared by dip-coating: effects of temperature during deposition

2012

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We prepared silica-poly(vinylpyrrolidone) (PVP) hybrid films via a temperature-controlled dip-coating process and investigated the influence of the coating temperature (i.e., the temperature of substrates, solutions and atmosphere) on the spontaneous pattern formation based on the ''coffee-ring effect''. Micron-scale stripe patterns were spontaneously formed on the surface of the films at high coating temperatures over 40 C during dip-coating. The stripe patterns were arranged perpendicular to the withdrawal direction, and the height and width of the patterns increased with increasing coating temperature. Such spontaneous pattern formation is attributed to the evaporation-driven capillary flow of coating solutions at the meniscus, and the stripe patterns with larger heights and widths are thought to be achieved by the capillary flow activated at higher coating temperatures.

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Sol–Gel-Derived Spheres for Spherical Microcavity

2007

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Encapsulation of light to small spheres ensures the highest quality factor ( Q factor) to enhance the interaction between light and materials. In this Account, we describe the fabrication of micrometer-sized spherical particles of organic-inorganic hybrid materials to study the potential ability as a spherical cavity laser. The spherical particles prepared by the vibrating orifice technique included those of nondoped and doped with organic dyes and rare-earth-metal ions, and some of them were cladded with low-index-coating hybrid materials. Coating of the spheres was carried out by aiming at practical applications: high refractive index spheres from n D = 1.72 to 2.5 prepared by the technique and glass spheres of n D = 1.93. They were pumped by second harmonic pulses of a Q-switched Nd:YAG laser (532 nm wavelength) and CW Ar (+) laser (514 nm wavelength) to investigate as spherical cavity microlasers. The emission from spheres originated from the photoluminescence of dopants and Raman scattering of matrix materials. Lasing or resonant light emission from these spheres were performed by the direct-laser-light-pumping and the light-coupling techniques using an optical waveguide coupler.

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Cited by 5 publications

References 5 publications

Spontaneous Pattern Formation Induced by Bénard–Marangoni Convection for Sol–Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility

Spontaneous Pattern Formation Induced by Bénard–Marangoni Convection for Sol–Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility

Spontaneous pattern formation based on the coffee-ring effect for organic–inorganic hybrid films prepared by dip-coating: effects of temperature during deposition

Sol–Gel-Derived Spheres for Spherical Microcavity

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