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We demonstrate a polymer brush assisted approach for the fabrication of continuous zirconium oxide (ZrO2) films over large areas with high uniformity (pin-hole free) on copper (Cu) substrates. This approach involves the use of a thiol-terminated polymethyl methacrylate brush (PMMA-SH) as the template layer for the selective infiltration of zirconium oxynitrate (ZrN2O7). The preparation of a highly uniform covalently grafted polymer monolayer on the Cu substrate is the critical factor in fabricating a metal oxide film of uniform thickness across the surface. Infiltration is reliant on the chemical interactions between the polymer functional group and the metal precursor. A following reductive H2 plasma treatment process results in ZrO2 film formation whilst the surface Cu2O passive oxide layer was reduced to a Cu/Cu2O interface. Fundamental analysis of the infiltration process and the resulting ZrO2 film was determined by XPS, and GA-FTIR. Results derived from these techniques confirm the inclusion of the ZrN2O7 into the polymer films. Cross-sectional transmission electron microscopy and energy dispersive X-ray mapping analysis corroborate the formation of ZrO2 layer at Cu substrate. We believe that this quick and facile methodology to prepare ZrO2 films is potentially scalable to other high-κ dielectric materials of high interest in microelectronic applications.

The bottom-up colloidal synthesis of photonic band gap (PBG) materials or photonic crystals (PCs) has attracted considerable interest in comparison to top-down approaches due to the relatively simple processing steps involved, the potential for large area sample production and the relatively low-costs associated with this approach for the fabrication of complex 3-dimensional (3D) structures. This research focuses on the colloidal synthesis of poly(methyl methacrylate) (PMMA)@Au core–shell (CS) structures, their bottom-up assembly into 3D metallodielectric PCs (MDPCs) and the demonstration of their potential to be used as surface enhanced Raman substrates (SERS) using the commonly deployed SERS reporter molecule, 4- aminothiolphenol. Here, monodispersed spherical PMMA particles were used both as a host material for Au nanoparticles (NPs) and as a crystal template to produce the MDPC structures. The materials engineering employed which involved combining the synthesis of monodispersed CS particles and the fabrication of their corresponding MDPCs enabled us to control the distribution of Au NPs in the PC structure and thereby investigate their light scattering, reflection and transmission properties including Raman scattering.

TiSiC-Cr coatings, with Cr and Si as additional elements, were deposited on Si, C 45 and 316 L steel substrates via cathodic arc evaporation. Two series of coatings with thicknesses in the range of 3.6–3.9 μm were produced, using either CH 4 or C 2 H 2 as carbon containing gas. For each series, different coatings were prepared by varying the carbon rich gas flow rate between 90 and 130 sccm, while maintaining constant cathode currents (110 and 100 A at TiSi and Cr cathodes, respectively), substrate bias (–200 V) and substrate temperature (∼320 °C). The coatings were analyzed for their mechanical characteristics (hardness, adhesion) and tribological performance (friction, wear), along with their elemental and phase composition, chemical bonds, crystalline structure and cross-sectional morphology. The coatings were found to be formed with nano-scale composite structures consisting of carbide crystallites (grain size of 3.1–8.2 nm) and amorphous hydrogenated carbon. The experimental results showed significant differences between the two coating series, where the films formed from C 2 H 2 exhibited markedly superior characteristics in terms of microstructure, morphology, hardness, friction behaviour and wear resistance. For the coatings prepared using CH 4 , the measured values of crystallite size, hardness, friction coefficient and wear rate were in the ranges of 7.2–8.2 nm, 26–30 GPa, 0.3–0.4 and 2.1–4.8 × 10 −6 mm 3 N −1 m −1 , respectively, while for the coatings grown in C 2 H 2 , the values of these characteristics were found to be in the ranges of 3.1–3.7 nm, 41–45 GPa, 0.1–0.2 and 1.4–3.0 × 10 −6 mm 3 N −1 m −1 , respectively. Among the investigated coatings, the one produced using C 2 H 2 at the highest flow rate (130 sccm) exhibited the highest hardness (45.1 GPa), the lowest friction coefficient (0.10) and the best wear resistance (wear rate of 1.4 × 10 −6 mm 3 N −1 m −1 ).

A method which combines polymer particle assembly, chemical infiltration and etching with an aerosol assisted deposition process is described for the fabrication of 3D inverse opal (10) structures with sub-micron periodicity and precision. This procedure not only overcomes limitations associated with slow, expensive micro-fabrication methods but also permits the tuning of refractive index contrast via the direct incorporation of photonically-active, preformed, tailored silicon nanostructures. It is demonstrated that this approach can be used to modify the photonic band gap (PBG) by effectively depositing/patterning optically active silicon nanocrystals (ncSi) onto the pore walls of a 3D inverse opal structure. This simple, yet effective method for preparing functional complex 3D structures has the potential to be used generically to fabricate a variety of functional porous 3D structures that could find application not only in new or improved photonic crystal (PC) devices but also in areas such as catalysis, separation, fuel cells technology, microelectronics and optoelectronics.

The microwave (MW)-assisted formation of ZnO micro-javelins from zinc nitrate and urea in aqueous solution is described. The particles (named as ‘micro-javelins’ because of their high aspect ratio and needle-like tips) grow hexagonally with well-defined facets in the 〈010〉 direction and pointed tips in (0001) direction. Powder X-ray diffraction patterns show the appearance of a strikingly dominant (1000) orientation. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations reveal the morphological evolution of these hexagonal ZnO particles with time. The effect of precursor concentrations, counterion type and MW irradiation power and their consequent influence on pH and Zn2+ ion concentration are investigated. A mechanism for the formation of the micro-javelins is postulated. The microwave induced supersaturation of Zn(OH)+ species under the weakly basic pH condition and the initial growth through the (000) direction (oxygen-rich face) are proposed to be the key factors that dictate the formation of these ZnO micro-javelins. The present one-step microwave process is a straightforward and a reproducible method for the bulk synthesis of defect-free ZnO micro-javelins, which would find potential applications in microelectronic devices (e.g. lasers, cantilevers in surface probing equipment, etc.).

A method for the preparation of anatase TiO2, which is stable to a temperature as high as 900 °C, without using any complex cationic dopants is presented. The synthetic procedure involves the reaction of titanium tetraisopropoxide (TTIP) with trifluoroacetic acid (TFA) followed by hydrolysis and sol−gel conversion to the xerogel and further calcination. The retention of the anatase phase to high temperatures can be attributed to the presence of small amounts of fluorine in the lattice, which is gradually removed between 500 and 900 °C as confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopic analysis. Samples prepared with a 1:16 TTIP/TFA composition calcined at 900 °C showed significantly higher photocatalytic activity compared to the control sample, standard commercial photocatalyst Degussa P25, and samples prepared using acetic acid and oxalic acid. The high-temperature anatase phase stability, determined by X-ray diffraction and Raman spectroscopy, coupled with its ...

We report here (i) a method for the synthesis of highly monodisperse silica@gold@silica core–shell–shell (CSS) particles (