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Control over the Structural and Optical Features of Nanoparticle-Based One-Dimensional Photonic Crystals

“…Among the defects typically caused by the process of spin coating of a particle suspension, the most relevant ones are those known as “striations” and “comets”. Striations are radially oriented undulations of the film and are the result of the rotation of a surface cell pattern. , Such pattern may be present in any liquid film with one of its surfaces exposed to air as a result of the Marangoni effect . In such films surface tension gradients, which in our case could be originated by local fluctuations of the suspended particle concentration or the temperature, induce fluid flows that set up a cell surface pattern.…”

Periodic Porous Stripe Patterning in a Polymer Blend Film Induced by Phase Separation during Spin-Casting

“…Such cellular and striping patterns are reported by several researchers, and their results are similar to the patterns observed in Figure 4. [25][26][27]30,31 The formation of the hill-andvalley pattern results from regular surface undulations created by convection rolls. The convection rolls are established by buoyancy and thermocapillary effects when a temperature gradient exists across a thin fluid layer.…”

“…The convection rolls are established by buoyancy and thermocapillary effects when a temperature gradient exists across a thin fluid layer. 26,36,37 For the convection-induced undulations, the surface tension at the hills is higher than that of the valleys. Higher surface tension in the hill pulls material up further from neighboring regions where the surface tension is lower (Figure 3, panel 2).…”

“…[16][17][18][19][20][21][22][23] A hill-and-valley periodic striping pattern is often observed on the surface of the spin-cast films in the literature. [24][25][26] It is concluded that this phenomenon is induced by capillary instabilities generated by both thermal and compositional gradients, in addition to the radial flow of a polymer and volatile solvent mixture. [26][27][28] Capillary instability is collectively known as Be ´nard-Marangoni convection, 29 and this convection is governed by a balance of the surface-tension-driven forces that are easily generated by solvent evaporation during spin-casting.…”

Applications of YBCO-coated conductors: a focus on the chemical solution deposition method

“…The angular velocity and the spinning time, combined with the solution viscosity and concentration, are manipulated to control the thickness of the wet film. 114,115 Spin coating has been widely used for the deposition of ferroelectrics. 79 The spray coating technique is based on the transformation of the coating solution into an aerosol by means of an ultrasonic nebulizer or appropriate pressure driven, nozzle-based atomizer.…”