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Crystal Films (crystal + film)
Selected AbstractsVisualization of Stacking Faults and their Formation in Colloidal Photonic Crystal Films,ADVANCED MATERIALS, Issue 6 2008E. Vekris We demonstrate experimentally that stacking faults give rise to unique optical spectra in self-assembled colloidal crystal films. These defects are shown to affect only bands in the high frequency region, while leaving the fundamental ,111, stopgap unaffected. Stacking faults are revealed to be caused by the incorporation of impurity spheres into the colloidal lattice during growth (pictured), a mechanism common to atomic crystallization. [source] One-Nanometer-Thick Seed Layer of Unilamellar Nanosheets Promotes Oriented Growth of Oxide Crystal Films,ADVANCED MATERIALS, Issue 2 2008T. Shibata Room-temperature fabrication of an ultimately thin seed layer using 2D oxide nanosheets is demonstrated. Flat nanosheets are tiled to form a highly organized monolayer with a thickness of ca. 1 nm on a glass substrate (see figure). Monolayer films of nanosheets such as Ca2Nb3O10 (2D square lattice) and MnO2 (2D hexagonal) successfully promote oriented film growth of oxide crystals such as SrTiO3 (cubic), TiO2 (tetragonal), and ZnO (hexagonal). [source] Dielectric Planar Defects in Colloidal Photonic Crystal Films,ADVANCED MATERIALS, Issue 4 2004N. Tétreault A straightforward synthetic route to produce colloidal photonic crystals containing dielectric planar defects of controlled thickness (see Figure) is presented. Allowed states that arise within the stop band as a result of this doping greatly modify the reflectance properties of the crystals, in good agreement with theoretical predictions. [source] Fabrication of a Superhydrophobic Surface from a Smectic Liquid-Crystal Defect ArrayADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Yun Ho Kim Abstract A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi-fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ,160° and a sliding angle of ,2° for a 10,µL water droplet. The results show that this phenomenon is due to the development of a dual-scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self-assembly in smectic liquid-crystalline materials. [source] Color- and Reflectance-Tunable Multiple Reflectors Assembled from Three Polymer FilmsADVANCED MATERIALS, Issue 14 2010Na Young Ha Tunings of reflectance and colors of multiple photonic bandgaps are demonstrated in the whole visible region by changing the polarization state of incident light. Two tunable systems are assembled from the same three materials of an anisotropic polymeric nematic liquid crystal film and two kinds of isotropic polymer film. The only difference between the two systems is the stacking sequence. [source] Fabrication of Thick (>10 ,m) GeO2 Ceramic Films by a Facile Liquid Phase Deposition ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2007Chengbin Jing GeO2 thick (>10 ,m) ceramic films were fabricated by facile liquid-phase deposition. The solubility of hexagonal GeO2 in water was increased ten times on adding aqueous ammonia at 70°C because of the formation of soluble Ge5O112,. With the addition of sulfuric acid, the alkaline GeO2,aqueous ammonia was neutralized, leading to the transformation of Ge5O112, into GeO2 precipitates. When the H2SO4/NH4OH molar ratio was higher than 11.7, immediate precipitation of GeO2 particles took place in the solution with no GeO2 particles deposited on the substrate. When the H2SO4/NH4OH molar ratio was decreased from 5.85 to 0.29, the precipitation process was retarded, leading to the gradual growth of uniform hexagonal GeO2 thick films on the substrates. The compactness of the film increased with a decrease in the H2SO4/NH4OH molar ratio. The growth of the GeO2 crystal film followed the Bravais,Freidel,Donnay,Harker and Hartman,Perdok models, and the cubic GeO2 particles with a size of about 10 ,m were finally formed on the film. No GeO2 precipitate was produced on the substrate when the GeO2,aqueous ammonia had an excessively low H2SO4/NH4OH molar ratio (,0.15) because the GeO2 solute did not reach the saturation level and the nucleation process could not take place on the substrate. The particles on the film surface deposited from the solution with an H2SO4/NH4OH molar ratio of 0.29 exhibited a nanopore structure. An initial study using this film as a support for KNO3 catalyst was carried out and the result revealed that the catalyst showed good catalytic activity of diesel soot oxidation. [source] Visualization of Stacking Faults and their Formation in Colloidal Photonic Crystal Films,ADVANCED MATERIALS, Issue 6 2008E. Vekris We demonstrate experimentally that stacking faults give rise to unique optical spectra in self-assembled colloidal crystal films. These defects are shown to affect only bands in the high frequency region, while leaving the fundamental ,111, stopgap unaffected. Stacking faults are revealed to be caused by the incorporation of impurity spheres into the colloidal lattice during growth (pictured), a mechanism common to atomic crystallization. [source] | ||||||||||