Home About us Contact
|
Home About us Contact | ||
|
|
||
Lateral Size (lateral + size)
Selected AbstractsMonomolecular-Layer Ba5Ta4O15 Nanosheets: Synthesis and Investigation of Photocatalytic Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2006T.-G. Xu Abstract Monomolecular-layer perovskite Ba5Ta4O15 nanosheets with hexagonal structure have been synthesized by a hydrothermal method. The thickness of the nanosheets is about 1.1,nm, which corresponds to a monolayer of Ba5Ta4O15 molecules, with the lateral size ranging from 50,to 200,nm. The optimal conditions for the formation of the nanosheets are maintaining the reactants above 270,°C for 24,h. A dissolution,recrystallization mechanism is suggested based on observations of the factors that influence nanosheet formation, such as reaction time, temperature, and basicity. Formation of Ba5Ta4O15 nanosheets takes precedence over other nanostructures under high concentrations of OH, because the hindering effect of OH, ions on the c -axis growth is strong. Thus, the extended growth rate of polyhedrons on one monolayer is much faster than the superposition rate of the monolayer, and the crystal grows more easily along the a - and b -planes. The Ba5Ta4O15 nanosheets show a high photocatalytic activity in the degradation of Rhodamine B and gaseous formaldehyde. The layered perovskite probably affects the photocatalytic activity by promoting the charge separation and delocalization of photogenerated electrons and holes. [source] Forming Highly Ordered Arrays of Functionalized Polymer Nanowires by Dewetting on Micropillars,ADVANCED MATERIALS, Issue 9 2007J. Guan 1D nanostructures are of great interest for numerous applications: a simple and low-cost process to generate large arrays of polymer nanowires by dewetting aqueous polymer solution on an array of micropillars is developed. These nanowires are typically less than 10,nm in lateral size and can be functionalized by incorporation of molecules or nanoparticles such as quantum dots (see figure). [source] Hierarchical Pattern Replication by Polymer Demixing,ADVANCED MATERIALS, Issue 9 2003M. Sprenger Structures with a lateral size of ,,100 nm have been created using a new replication method based on the demixing of a ternary polymer mixture during spin-coating. The technique, which relies on the interfacial wetting of one of the polymer components at the interface of the other two, produces structures (see Figure) that are significantly smaller than the lateral dimensions of the substrate prepattern. [source] Wide-range length metrology by dual-imaging-unit atomic force microscope based on porous aluminaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Dongxian Zhang Abstract A new dual-imaging-unit atomic force microscope (DIU-AFM) was developed for wide-range length metrology. In the DIU-AFM, two AFM units were combined, one as a reference unit, and the other a test one. Their probes with Z piezo elements and tips were horizontally set in parallel at the same height to reduce errors due to geometric asymmetry. An XY scanner was attached to an XY block that was able to move in the X direction with a step of about 500 nm. A standard porous alumina film was employed as the reference sample. Both reference sample and test sample were installed at the center of the XY scanner on the same surface and were simultaneously imaged. The two images had the same lateral size, and thus the length of the test sample image could be accurately measured by counting the number of periodic features of the reference one. The XY block together with the XY scanner were next moved in the X direction for about 1.5 ,m and a second pair of reference and test images were obtained by activating the scanner. In this way, a series of pairs of images were acquired and could be spliced into two wide-range reference and test images, respectively. Again, the two spliced images were of the same size and the length of test image was measured based on the reference one. This article presents a discussion about the structure and control of the DIU-AFM system. Some experiments were carried out on the system to demonstrate the method of length calculation and measurement. Experiments show a satisfactory result of wide-range length metrology based on the hexagonal features of the porous alumina with a periodic length of several tens of nanometers. Using this method the DIU-AFM is capable of realizing nanometer-order accuracy length metrology when covering a wide range from micron to several hundreds of microns, or even up to millimeter order. Microsc. Res. Tech. 64:223,227, 2004. © 2004 Wiley-Liss, Inc. [source] Submicron resolution X-ray diffraction from periodically patterned GaAs nanorods grown onto Ge[111]PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009Anton Davydok Abstract We present high-resolution X-ray diffraction pattern of periodic GaAs nanorods (NRs) ensembles and individual GaAs NRs grown catalyst-free throughout a pre-patterned amorphous SiNx mask onto Ge[111]B surfaces by selective-area MOVPE method. To the best of our knowledge this is the first report about nano-structure X-ray characterization growth on non-polar substrate. The experiment has been performed at home laboratory and using synchrotron radiation using a micro-sized beam prepared by compound refractive lenses. Due to the non-polar character of the substrate the shapes of NRs appear not uniform and vary between deformed hexagonal and trigonal in symmetry. Because the average diameter of NRs equals the experimental resolution certain cuts through slightly inclined edges or corners of individual NRs with lateral size of about 225,nm could be selected using spatially resolved reciprocal space mapping. [source] Relaxor-based thin film memories and the depolarizing field problemPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007Manuel I. Marqués Abstract A simple model for a thin film memory based on a first neighbor interacting model is studied in detail. We have found that the minimum possible value for the thickness (D) as a function of the lateral size of the memory (L), the screening of the charges at the substrate (S) and the strength of the ferroelectric interaction (J), in order to obtain spontaneous polarization is D = SL /2J. We propose a new mechanism to obtain miniaturization of thin film memories to a single layer based on the use of relaxor ferroelectrics instead of regular ferroelectrics. Under the hypothesis of an internal organization of the random fields inside the nanofilm we show analytically how it should be possible to miniaturize the memory to a width as small as D = 1 for any value of L, J and S. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] First step to Si photonics: synthesis of quantum dot light-emitters on GaP substrate by MBEPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2009Weiming Guo Abstract We have grown InAs and InP quantum dots (QDs) on GaP substrate by Molecular Beam Epitaxy (MBE) and analysed them by Atomic Force Microscopy (AFM) and photoluminescence (PL). AFM images confirm the formation of InAs and InP QDs. Largest InAs QDs density is obtained at a growth temperature of 450 °C and under an AsH3 flux of 0.3SCCM. The evolution of QDs shape and absence of photoluminescence indicate a likely plastic relaxation of the strain between InAs and GaP. Concerning InP/GaP QDs, their lateral size, height and density indicate good quality QDs. Photoluminescence signal has been detected for capped InP/GaP QDs until 180 K. The unchanged peak position with respect to InP coverage is attributed to the nearly constant height of the QDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Vertical (La,Sr)MnO3 Nanorods from Track-Etched Polymers Directly Buffering SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Adrián Carretero-Genevrier Abstract A novel and general methodology for preparing vertical, complex-oxide nanostructures from a sol,gel-based polymer-precursor solutions is developed using track-etched polymers directly buffering substrates. This method is able to develop a nanostructure over the entire substrate, the dimensions and localization of the vertical nanostructures being preset by the polymeric nanotemplate. Thereby, nanostructures with lateral sizes in the range of 100 to 300,nm and up to 500,nm in height have been grown. Two examples are presented herein, the latter being the evolution of the initial, metastable nanostructure. Specifically, La0.7Sr0.3MnO3 polycrystalline rods are grown at mild temperatures (800,°C); upon strong thermal activation (1000,°C) they suffer a profound transformation into vertical, single-crystalline (La,Sr)xOy nanopyramids sitting on a La0.7Sr0.3MnO3 epitaxial wetting layer. The driving force for this outstanding nanostructural evolution is the minimization of the total energy of the system, which is reached by reducing the grain-boundary, total-surface, and strain-relaxation energies. Finally, advanced electron-microscopy techniques are used to highlight the complex phase separation and structural transformations occurring when the metastable state is overcome. [source] Spectral characteristics of single InAs/InGaAs quantum dots in a quantum wellPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003L. Worschech Abstract Self assembled InAs quantum dots embedded in an InGaAs quantum well were grown by molecular beam epitaxy. At room temperature these dots in a well (DWELLS) have an emission wavelength of 1.3,,m. Small mesas with lateral sizes down to 200 × 200 nm2 were fabricated by electron beam lithography and etching techniques. By photoluminescence spectroscopy at low temperatures we observe narrow lines, which we attribute to excitons and excitonic molecules. Biexciton binding energies ranging between 3.5,5,meV are found. [source] | |||||||||||||