Sergei A. Kulinich

How Wetting Hysteresis Influences Ice Adhesion Strength on Superhydrophobic Surfaces

In this work, we measured the adhesion strength of artificially created glaze ice (similar to accreted in nature) on rough fluoropolymer-based hydrophobic surfaces with different contact angle (CA) and wetting hysteresis. The previously reported direct correlation between ice repellency and CA on superhydrophobic surfaces is shown to be only valid for surfaces with low wetting hysteresis. Another correlation was found between wetting hysteresis and ice adhesion strength on rough surfaces with similar chemistry.

Morphology Control of Nanostructures via Surface Reaction of Metal Nanodroplets

We report on the controllable synthesis of diverse nanostructures using laser ablation of a metal target in a liquid medium. The nanodroplets generated by laser ablation react with the liquid and produce various nanostructures, such as hollow nanoparticles, core-shell nanoparticles, heterostructures, nanocubes, and ordered arrays. A millisecond laser with low power density is essential for obtaining such metal nanodroplets, while the target material, the reactivity of liquid medium, and the laser frequency are decisive for controlling the morphology and size of the nanostructures produced. This green and powerful technique can be extended to different material systems for obtaining various nanostructures.

Epitaxial ZnO Nanowire-on-Nanoplate Structures as Efficient and Transferable Field Emitters

Highly epitaxial ZnO nanowire-on-nanoplate structures as efficient and transferable electron field emitters are reported here. Well-faceted ZnO nanoplates can be used as efficient substrates for the epitaxial growth of nanowires with a sharp and high-quality interface, which significantly improves its field emitter performance. Because of its scalable preparation, high performance and facile transfer, the novel material is of high potential for applications in various optoelectronic devices.

Hollow Nanoparticles of Metal Oxides and Sulfides: Fast Preparation via Laser Ablation in Liquid

In this work, diverse hollow nanoparticles of metal oxides and sulfides were prepared by simply laser ablating metal targets in properly chosen liquids. The Kirkendall voiding and the selective heating with an infrared laser were shown to work as two independent mechanisms for the formation of such hollow nanoparticles in only one- or two-step synthesis approaches. One of the prepared materials, ZnS hollow nanoparticles, showed high performance in gas sensing. The simple, fast, inexpensive technique that is proposed demonstrates very promising perspectives.

A general one-pot strategy for the synthesis of high-performance transparent-conducting-oxide nanocrystal inks for all-solution-processed devices.

For all-solution-processed (ASP) devices, transparent conducting oxide (TCO) nanocrystal (NC) inks are anticipated as the next-generation electrodes to replace both those synthesized by sputtering techniques and those consisting of rare metals, but a universal and one-pot method to prepare these inks is still lacking. A universal one-pot strategy is now described; through simply heating a mixture of metal-organic precursors a wide range of TCO NC inks, which can be assembled into high-performance electrodes for use in ASP optoelectronics, were synthesized. This method can be used for various oxide NC inks with yields as high as 10 g. The formed NCs are of high crystallinity, uniform morphology, monodispersity, and high ink stability and feature effective doping. Therefore, the inks can be readily assembled into films with a surface roughness of 1.6 nm. Typically, a sheet resistance of 110 Ω sq(-1) can be achieved with a transmittance of 88%, which is the best performance for TCO NC ink-based electrodes described to date. These electrodes can thus drive a polymer light-emitting diode (PLED) with a luminance of 2200 cd m(-2) at 100 mA cm(-2).

Structure and properties of CaO- and ZrO2-doped TiCxNy coatings for biomedical applications

Abstract In the present work multicomponent thin films based on the systems Ti–Ca–C–O–N and Ti–Zr–C–O–N have been deposited and evaluated. TiC 0.5 +10% CaO and TiC 0.5 +10% ZrO 2 targets were manufactured by means of the self-propagating high-temperature synthesis (SHS) method. The synthesized targets were subjected to DC magnetron sputtering in an atmosphere of argon or in a gaseous mixture of argon and nitrogen. The films were characterized in terms of their structure, surface topography, mechanical properties and tribological behavior. The films deposited on Si substrates under optimal conditions showed high hardness in the range of 36–40 GPa, low Youngs modulus 260–300 GPa and high percentage of elastic recovery 70–75%. The CaO- and ZrO 2 -doped Ti–C–N films showed significantly lower friction coefficient and wear rate against WC+6% Co alloy in comparison to conventional magnetron–sputtered TiC and TiN films. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments (in mice). In vitro studies involved the investigation of the proliferation of fibroblasts Rat-1 and epithelial cells IAR-2 at the tested films and morphometric analysis of the cells cultivated on the films. Fibroblasts and epithelial cells were seeded on the coverslips, coated with examined films and incubated at 37 °C for 24, 48 and 72 h. We did not detect statistically significant differences in the attachment, spreading and proliferation of cultured cells on the coated and the uncoated substrata. The adhesion and proliferation of cells was good at all investigated films. We also did not observe any inflammatory reactions on the implants, inserted under the mouse skin.

Optimizing Hybridization of 1T and 2H Phases in MoS2 Monolayers to Improve Capacitances of Supercapacitors

We report on a 100-fold capacitance increase in MoS2-based supercapacitors achieved via optimizing the in-plane 1T-2H phase hybridization of the monolayers. Chemically exfoliated MoS2 monolayers were annealed at low temperature to tune their 1T content from 2% to 60%. The obtained hybridization states were confirmed by X-ray photoelectron and Raman spectroscopies. After optimizing the hybridization degree, the electrode based on MoS2 monolayers with 40% of the 1T phase exhibited outstanding performance with a resistance as low as 0.68 kΩ sq−1, specific capacitance of 366.9 F g−1, and retention ratio of 92.2% after 1000 cycles at current densities of 0.5 A g−1. GRAPHICAL ABSTRACT

On conversion coating treatments to replace chromating for Al alloys: Recent developments and possible future directions

Anticorrosive protection of Al alloys still depends heavily on the use of chromates, which are widely and universally employed as chromate conversion coating and chromic acid anodising pretreatments. The replacement of chromate based treatments with more environmentally compliant processes and materials has been identified as a high priority. The aim of this paper is to review the most recent developments in the application of common inorganic protection layers based on conversion coatings for Al alloys. The review lists and discusses the majority of conversion coatings, including those formed through anodisation, on Al alloys as potential replacements to the most widely used treatments based on chromate chemistry.

Structure and Physical-Mechanical Properties of Nanostructured Thin Films

The structure and mechanical properties of nanostructured thin films based on carbides, nitrides, and borides of transition metals are described. The mechanisms of localized deformation of the films during indentation are compared. It is shown that the tendency of a material to form shear bands during deformation can be predicted using the parameter H3/E2, which describes the resistance of the material to plastic deformation. The columnar structure of the films is found to play an important role during deformation, which proceeds via slipping of columnar structural elements along the direction of an applied load.

Localized deformation of multicomponent thin films

A comparative analysis of fracture for various films is presented. Films of Cr–B, Ti–Si–N, Ti–B–N and Ti–Cr–B–N were deposited by DC magnetron sputtering of composite targets. The indentation of the as-deposited films on ( 001 ) Si substrates was made using Vickers microhardness tester at a load of 10, 25 and 50 g. The scanning electron microscopy and atomic force microscopy studies were fulfilled to investigate the film behavior during localized deformation. Both homogeneous and localized inhomogeneous deformations of the fracture surface were observed and described. Isolated particles located within the area of deformation were frequently observed. The films were characterized in terms of their structure, hardness, elastic modulus, elastic recovery and surface topography. The H yE ratio (i.e. resistance to plastic deformation ) was proposed to be a ranking parameter 32 for the prediction of shear banding under the localized deformation. The correlation between the surface roughness, surface relief inside indentations and columnar fracture morphology was outlined. It was suggested that column sliding is the dominant fracture mechanism resulting in the formation of breaking-away particles under unloading. 2002 Elsevier Science B.V. All rights reserved.