Interface between electroless amorphous Ni–Cu–P coatings and Al substrate

The initial phase arising at the interface with aluminum substrate during electroless deposition of amorphous high phosphorus (16–19 at.%) Ni–Cu–P alloy with alloyed copper 1.7–3.4 at.% is studied. Stripped deposit foils are inspected by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy coupled with energy dispersive X-ray analysis (TEM-EDX). Depending on the plating conditions, various particles, some of them crystalline, are revealed at the foils sides formerly adhering to the substrate. EDX analysis of the crystallites shows diverse copper contents of about 34–64 at.%, without any phosphorus. Electron diffraction analysis indicates a lattice structure very close to that of Cu. The presence of a phase without phosphorus and enriched in copper at the interface with the Al substrate is also confirmed by Auger electron spectroscopy. This initially arising crystalline phase might exert a limited effect on the main properties of bulk Ni–Cu–P deposits: the composition uniformity through the thickness, amorphous structure and paramagnetic behavior. A modification of the plating process is recommended, which is decreasing the probability of inhomogeneities formation.     

Fractal initialization for high-quality mapping with self-organizing maps

Initialization of self-organizing maps is typically based on random vectors within the given input space. The implicit problem with random initialization is the overlap (entanglement) of connections between neurons. In this paper, we present a new method of initialization based on a set of self-similar curves known as Hilbert curves. Hilbert curves can be scaled in network size for the number of neurons based on a simple recursive (fractal) technique, implicit in the properties of Hilbert curves. We have shown that when using Hilbert curve vector (HCV) initialization in both classical SOM algorithm and in a parallel-growing algorithm (ParaSOM), the neural network reaches better coverage and faster organization.     

Preparation and characterisation of platinum- and gold-coated copper, iron, cobalt and nickel deposits on glassy carbon substrates

Pt- and Au-coated Cu, Fe, Co and Ni deposits have been formed on glassy carbon (GC) substrates by electrodeposition of controlled amounts of the core metal onto the substrate and its subsequent partial replacement by Pt or Au upon immersion into a chloroplatinic or chlorolauric solution. This process resulted in a thin Pt or Au shell over the bimetallic particle as electrochemical evidence suggests, while indicative sputter-etch Auger Electron Spectroscopy points to the coexistence of the two metals in the particle core. SEM/EDS characterisation of the deposits revealed the existence of Pt(M) and Au(M) extensively agglomerated nanoparticles (M: Cu, Fe, Co, Ni). The surface electrochemistry of the deposits (hydrogen adsorption/desorption on Pt and oxide formation/stripping on Au) proved the complete coverage of the bimetallic particles by Pt or Au and allowed an estimate of their electroactive surface area. The study of hydrogen evolution at these deposits points to a modification of the electronic properties of the Pt and Au surface layers by the core metal (due to strain effects and/or ligand-electronic interactions) and further confirmed that these layers form a very thin outer shell.     

Incubation phenomena during UV‐pulse excimer laser processing of silicone elastomers

Observations of the interaction of poly(dimethylsiloxane) (PDMS) sheet (210 μm thick) with KrF excimer laser irradiation (λ = 248 nm), with low energy of 50 mJ/pulse are presented. The negative ablation or swelling of the material caused by low frequency pulse irradiation is characterized by optical microscopy, μ‐Raman spectrometry and X‐ray micro‐tomography. The appearance of defected areas in the form of cones inside the sheet and changes of material chemistry are discussed. These phenomena are considered as a precursor of the ablation occurring after passing a threshold of absorbed laser irradiation energy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44541.     

Photochromic films prepared by vacuum co-deposition of polymer and spiropyrans

Photochromic polymer thin films have been prepared by vacuum co-deposition of PTFE and several spirocompounds. Their photochromic properties were studied with the use of the spectral-kinetic method. A number of positive properties for application of these films were found.     

New bistable organic photochromic compounds for bitwise working optical memory

The results of our spectral and kinetic studies for some photochromic compounds (58 diarylethenes and 9 fulgimides) are presented. Aiming at targeted synthesis of new photochromic compounds, the structure-photochromic behavior relationship (SPBR) for the synthesized compounds has been analyzed. The perspectives for application of these compounds in development of recording media for use in optical memory devices are outlined. The text was submitted by the authors in English.     

Electroless deposited Ni–Re–P, Ni–W–P and Ni–Re–W–P alloys

Coatings of electroless Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys were plated in alkaline citrate baths containing amino alcohols, but not free ammonia ions. The reference Ni–P alloy was used as an intermediate layer in the sandwich: Ni–Me–P/Ni–P/substrate. An extremely homogeneous thickness distribution of all alloy components was found by applying scanning Auger electron spectroscopy (SAES(. The inclusion of refractory metals at the expense of nickel and without substantial change in phosphorus content was established. A non-oxidized state of the codeposited Re and W in Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys was determined by means of X-ray photoelectron spectroscopy examination, as well as by SAES profiles, revealing the absence of oxygen throughout the coatings. All alloy films are amorphous and paramagnetic.     

Preparation and photoelectrochemical characterisation of electrosynthesised titanium dioxide deposits on stainless steel substrates

TiO₂ films on stainless steel 304 substrates have been prepared from acidic aqueous solutions of TiOSO₄ and H₂O₂ by room temperature potentiostatic cathodic electrosynthesis. Coatings of varied thickness were produced by repeating the deposition step two or three times accompanied by drying steps in between. The resulting gel films were annealed at 400 °C to obtain crystalline TiO₂ (anatase) films with loadings in the 0.1-1 mg cm⁻² range. The deposits had a macro-particulate structure and adhered well on stainless steel 304. The electroactive surface area of the composite electrodes was estimated by cyclic voltammetry in the dark, while their photoelectrochemical behaviour was investigated by photo-voltammetry under UV illumination, both in the presence and absence of oxidizable organics. The effect of deposit thickness on photocurrent and an indicative comparison of electrosynthesised TiO₂/stainless steel 304 photoelectrodes with thermal and particulate TiO₂/Ti electrodes are also presented.     

Structure and Physicochemical Properties of Glasses in the Li2S–LiPO3 System

The temperature–concentration dependence of the electrical conductivity of glasses in the Li₂O–LiPO₃ and Li₂S–LiPO₃ systems is investigated. With the use of the Tubandt method, it is demonstrated that the electric current in glasses of these systems is provided by migration of lithium ions. The concentration dependence of the electrical conductivity is interpreted using the obtained data on the IR absorption spectra, density, microhardness, ultrasonic velocity, etc. It is found that the electrical conductivity of glasses in the Li₂S–LiPO₃ system is more than 10³ times higher than that in pure LiPO₃. The observed increase in the electrical conductivity is explained by the formation of sulfur-containing polar structural–chemical groupings of the Li⁺[S^–PO_3/2] type, whose dissociation energy is lower than that of similar oxide polar structural fragments. This results in an increase in the number of lithium ions involved in the electricity transport due to an increase in the degree of dissociation of polar structural–chemical units.