Silver Selectively Deposited on Ferroelectric Barium Titanate Domains Enable Creation of Metallic Patterns with Submicro
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tissue papers with well-defined lutein concentrations were attached. Strong and clearly resolved Raman signals were measured with the intensity varying linearly with lutein concentration. Further experiments were carried out on the healthy eye of a volunteer. In these measurements the laser power was 300 µW, the exposure time 1 s, and the spot diameter on the macula maintained at about 1 mm. This corresponds to a dose of ~38 mJ/cm2, a value which is about 400 times lower than the ANSI maximum permissible safe dose of 15.5 J/cm2. “Raman signals are typically of very weak intensity and therefore we usually need to use relatively powerful lasers in combination with sophisticated light collection and analysis instrumentation,” said Gellermann. “As physicists, we’re trained to not to stare into lasers. But, when our colleagues in ophthalmology pointed out the strong need to measure macular pigments in a noninvasive and objective way, we decided to take this unique approach and it has worked out very well.” CORA LIND
the silver deposition. The researchers believe that this selective deposition of silver in up domains was not due to the preferential adsorption of Ag+ cations before reduction, but to the influence of the static dipolar fields in the domains. The field in up domains pushed electrons to the surface where they could reduce silver, while the field in down domains urged electrons away from the surface
where they were unable to react with the silver cations. According to the researchers, this study provides a potential approach to “creating metallic patterns with submicron features.” They said that this highly selective deposition technique would make it possible to “predefine a pattern and then metallize the surface” in the future. XIANLONG GE
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Silver Selectively Deposited on Ferroelectric Barium Titanate Domains Enable Creation of Metallic Patterns with Submicron Features In the February issue of Chemistry of Materials, Jennifer L. Giocondi and Gregory S. Rohrer from the Department of Materials Science and Engineering at Carnegie Mellon University reported that silver had been selectively deposited on some specific ferroelectric BaTiO3 domains during photochemical reduction of aqueous Ag+. This domain decoration-related finding makes it possible to create metallic patterns with submicron features. In this study, the photochemical reduction was accomplished by exposing the surface of BaTiO3 polycrystals to a 300-W Hg lamp for 3 s in the presence of a 0.115 M aqueous AgNO3 solution. The sample, after rinsing and drying, was imaged using atomic force microscopy (AFM). By comparing the topographic AFM images of the samples before and after the reduction reaction, silver appeared to be selectively deposited on certain regions of the surface that corresponded
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