This Review highlights the large number of methods to exploit colloidal assembly of comparably simple particles with nano- to micrometer dimensions in order to access complex structural hierarchies from nanoscopic over microscopic to macroscopic dimensions

Advances in colloidal assembly: the design of structure and hierarchy in two and three dimensions.

It is of fundamental importance to establish whether there is a limit to how thin a superconducting wire can be, while retaining its superconducting character--and if there is a limit, to determine what sets it. This issue may also be of practical importance in defining the limit to miniaturization of superconducting electronic circuits. At high temperatures, the resistance of linear superconductors is caused by excitations called thermally activated phase slips. Quantum tunnelling of phase slips is another possible source of resistance that is still being debated. It has been theoretically predicted that such quantum phase slips can destroy superconductivity in very narrow wires. Here we report resistance measurements on ultrathin ( Rq, which we explain in terms of proliferation of quantum phase slips and a corresponding localization of Cooper pairs.

Quantum suppression of superconductivity in ultrathin nanowires

Quantum coherent effects, phase transitions, and the dissipative dynamics of ultra small tunnel junctions

Nanofabrication by electron beam lithography and its applications

Templating with colloidal crystals composed of monodisperse spheres is a convenient chemical method to obtain porous materials with well-ordered periodicity and interconnected pore systems. The three-dimensionally ordered macroporous (3DOM) products or inverse opals are of interest for numerous applications, both for the optical properties related to structural color of these photonic crystal materials and because of their bicontinuous nanostructure, i.e., a continuous nanostructured skeleton with large interfacial area and a three-dimensionally interconnected pore system with low tortuosity. This review outlines various synthetic methods used to control the morphology of 3DOM materials with different compositions. It highlights aspects of the choice of colloidal particles, assembly of the colloidal crystal template, infiltration and processing, template removal, and other necessary modifications to enhance the functionality of the materials. It also considers syntheses within the confinement of 3DOM materials and summarizes characterization methods that are particularly useful in the analysis of 3DOM materials. The review then discusses chemical applications of 3DOM materials, namely sorption and controlled release, optical and electrochemical sensors, solar cells, lithium ion batteries, supercapacitors, fuel cells, and environmental and chemical fuel catalysis. A focus is on structural features and materials properties that enable these applications.

Design and functionality of colloidal-crystal-templated materials—chemical applications of inverse opals

We demonstrate the epitaxial growth of a metastable (with respect to the bulk) hcp crystal as well as any other close-packed stacking sequence of colloidal hard spheres. At certain stretched and compressed lattices we furthermore observed growth of a non-close-packed superstructure and of a perfect (100)-aligned fcc crystal. Perfect template-induced hcp-crystal growth occurs at lattice spacings that are larger than for bulk crystallization, indicative of prefreezing. Small mismatches lead to increased out-of-plane displacements. Large mismatches prevent crystallization in the surface layers.

/pdf/hard-sphere-crystals-with-hcp-and-non-close-packed-structure-zrw059odrp.pdf

Hard-Sphere Crystals with hcp and Non-Close-Packed Structure Grown by Colloidal Epitaxy

Effects of charging energy were studied in small-capacitance aluminum tunnel junctions in the normal state, with tunnel resistance Rt between 0.2 and 80 kΩ. Single junctions, chains and 2-dimensional arrays were fabricated. This allowed investigation of the influence of lead capacitance. For Rt > 1 kΩ the voltage offset ("Coulomb gap") determined from the I-V curve at high current is consistent with the capacitance calculated from junction area only. For single junctions with Rt near or below 10 kΩ at low current the charging effects are strongly suppressed. Results of chains with arbitrary Rt show the suppression of charging effects by dissipation. The R(T) curves are in good agreement with theory and geometrical capacitance.

http://iopscience.iop.org/article/10.1209/0295-5075/10/1/014/pdf

Influence of Dissipation on the Coulomb Blockade in Small Tunnel Junctions

We demonstrate the epitaxial growth of hard-sphere hcp and double hcp crystals using a surface pattern that directly dictates the stacking sequence. A detailed three-dimensional analysis based on real-space measurements is performed on crystal structure as a function of template-crystal mismatch, which demonstrates the possibilities of colloidal epitaxy as a model system for studying the effects of a patterned substrate on crystal structure. Perfect template-induced hcp-crystal growth occurs at an isotropically deformed template. At deformed lattices we observe growth of a non-close-packed superstructure and of a perfect (100)-aligned fcc crystal. Small mismatches lead to increased out-of-plane displacements followed by a structural breakup in “crystal” grains where particle positions in successive layers are strictly periodic and “defect” grains where these positions are displaced with respect to each other. Large mismatches prevent crystallization in the surface layers. The volume fraction was found to vary drastically (up to about 20%) as a function of template deformation.

/pdf/epitaxial-growth-of-a-colloidal-hard-sphere-hcp-crystal-and-2o8d3y78en.pdf

Epitaxial growth of a colloidal hard-sphere hcp crystal and the effects of epitaxial mismatch on crystal structure

A pattern of repulsive, charged lines is shown to direct three-dimensional (3D) crystallization in a system of long-range repulsive, density-matched colloids. At volume fractions where the bulk phase behavior leads to bcc crystallization, the 1D template was found to induce formation of a metastable fcc crystal. The bcc crystals were oriented with the (100) or the (110) plane, with twofold twinning, parallel to the template. The template further induced prefreezing of the (100) plane. At a large mismatch between template and interparticle spacing, 1D strings form in the surface layer of a 3D crystal.

/pdf/epitaxial-crystal-growth-of-charged-colloids-36gr80y6gr.pdf

J. Romijn

Papers

Hard-Sphere Crystals with hcp and Non-Close-Packed Structure Grown by Colloidal Epitaxy

Influence of Dissipation on the Coulomb Blockade in Small Tunnel Junctions

Epitaxial growth of a colloidal hard-sphere hcp crystal and the effects of epitaxial mismatch on crystal structure

Epitaxial Crystal Growth of Charged Colloids

Hydrogen SilsesQuioxane, a high-resolution negative tone e-beam resist, investigated for its applicability in photon-based lithographies