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This work is devoted to studying the aggregation effect on the nonlinear optical (NLO) and charge transport (CT) properties of low-symmetry phthalocyanines bearing a cyclotriphosphazene moiety, a monomer, and clamshell-type bis-phthalocyanine. FE-SEM and AFM studies revealed ordered nanoaggregation in these compounds, represented as repeating objects of regular configuration, globules (340–480 nm), which contain small aggregates inside their cavity, similar to smoothed polygons (ca. 40 nm). Such specificity is not characteristic of other functionalized phthalocyanines, which we dealt with earlier. A new spectral method for estimating the aggregation threshold based on the change in extinction with increasing concentration of solutions was also implemented, and the effect of aggregation on optical limiting was demonstrated. The behavior of isomers and rotamers of bis-phthalocyanine in the presence of electric fields of various strengths was investigated with the DFT calculations, and that partially corresponds to the impact of laser radiation on molecules. It was shown that the unusual behavior of the trans-isomer in FF-DFT calculations is the reason for the worsening of the NLO and CT characteristics of bis-phthalocyanine, in which the macrocycles are strapped through a phosphazene spacer. An advanced method of multiparametric analysis has been implemented to evaluate the NLO and CT properties of the dyes in general.

Composite materials filled with ferromagnetic inclusions are useful in the development of various microwave devices. The performance of such devices is determined both by material properties (such as the saturation magnetization and the permeability) and by the demagnetization effects. The paper is devoted to the study of the demagnetization effect on the permeability measurements of composites under external magnetic bias. The microwave permeability of composites filled with flake sendust (Fe-Si-Al alloy) particles is measured as a function of frequency and the external magnetic field. The measurements are carried out by the Nicolson–Ross–Weir technique in a 7/3 coaxial line in the frequency range of 0.1 to 20 GHz by a vector network analyzer. It is found that the magnetic loss peak is split under external fields of more than 1.5 kOe. The main aim of this paper is to study the causes of this splitting and to interpret the observed magnetic loss peaks. To study this effect, the samples of various thicknesses and the samples with isotropic and anisotropic orientations of particles are measured. The particles in the anisotropic samples are oriented by a strong uniform magnetic field. At a small fraction of inclusions, the permanent magnetic field is demagnetized on the individual particles rather than the whole sample. The splitting of the magnetic loss peak of the isotropic sample is caused by different orientations of particles in the sample. At a high fraction of inclusions, the permanent magnetic field is demagnetized on the whole sample and the magnetic loss peak of the isotropic sample is not split. The saturation magnetization of the material is found by measurements under the external magnetic field of the anisotropic sample.

Two new mononuclear complexes based on the anion 3-cyano-4-dicyanomethylene-5-oxo-4,5-dihydro-1H-pyrrol-2-olate (C8HN4O2− = HA−) and Mn2+ or Zn2+ cations, namely [Mn(HA)2(H2O)4]·2H2O (1) and [Zn(HA)2(H2O)4] (2), were synthesized and characterized by single-crystal X-ray diffraction and photoluminescence spectroscopy. Complexes 1 and 2 crystallize in the triclinic space group P. Units [M(HA)2(H2O)4] (M = Mn, Zn) are the basic building blocks in both 1 and 2 crystal structures. The metal cation, located on an inversion center, is bound to two nitrogen atoms of two HA− and four water oxygen atoms. Units [M(HA)2(H2O)4] are connected by π–π stacking interactions between anions HA− and by hydrogen bonds to form a 3D crystal structure. Complexes 1 and 2 are isostructural with previously reported complexes [Cd(HA)2(H2O)4]·2H2O and [Cu(HA)2(H2O)4], respectively. A comparison between the luminescence properties of isostructural complexes confirms that the incompletely filled 3d subshell (3d5, 3d9) of a divalent metal cation is a key factor leading to the total luminescence quenching of anion HA− upon complexation with metal cations. Salts M(HA)2 (M = Mn, Cd, Cu, or Zn) adsorbed on cellulose paper display thermo-sensitive luminescence. The luminescence is due to HA− anions. The intensity of the luminescence peak reversibly decreases by 6–7 times upon heating from 27 up to 123 °C.

Protective SiO2 coating deposited to iron microparticles is highly demanded both for the chemical and magnetic performance of the latter. Hydrolysis of tetraethoxysilane is the crucial method for SiO2 deposition from a solution. The capabilities of this technique have not been thoroughly studied yet. Here, two factors were tested to affect the chemical composition and the thickness of the SiO2 shell. It was found that an increase in the hydrolysis reaction time thickened the SiO2 shell from 100 to 200 nm. Moreover, a decrease in the acidity of the reaction mixture not only thickened the shell but also varied the chemical composition from SiO3.0 to SiO8.6. The thickness and composition of the dielectric layer were studied by scanning electron microscopy and energy-dispersive X-ray analysis. Microwave permeability and permittivity of the SiO2-coated iron particles mixed with a paraffin wax matrix were measured by the coaxial line technique. An increase in thickness of the silica layer decreased the real quasi-static permittivity. The changes observed were shown to agree with the Maxwell Garnett effective medium theory. The new method developed to fine-tune the chemical properties of the protective SiO2 shell may be helpful for new magnetic biosensor designs as it allows for biocompatibility adjustment.

Spray pyrolysis of an aqueous solution of iron nitrate, proceeded with reduction of the product in hydrogen, gave iron powder with micron-sized hollow particles. Coating these iron particles with SiO2 through tetraethyl orthosilicate hydrolysis prevented interparticle electrical contacts and suppressed DC percolation. This material shows a high ferromagnetic resonance frequency of 18 GHz, low permittivity, and weighs 20% less than common carbonyl iron. Potential microwave applications are for inductors and electromagnetic interference shielding designs.

Direct metallation of 2-hydroxyphthalocyanine J-type slipped-cofacial dimeric ligand by Mg, Zn, Cu, Ni and Co salts has been carried out to obtain corresponding metal complexes selectively without any noticeable dissociation or polymerization of the starting ligand. Integrated analysis of aggregation properties in the synthesized series has been conducted with the involvement of AFM microscopy, UV/Vis spectroscopy and theoretical assessment. As a result, a nonlinear relationship between absorption and concentration was found, with aggregation beginning to appear at concentrations above 3.3 × 10−5 mol L−1 with predominant formation of trimers from the dimeric molecules in THF solutions.

Vanadium dioxide (VO2) is a promising material for electronics and optics due to abrupt change in conductivity of VO2 that occurs at ∼68 °C, which is the metal-insulator transition temperature. The abruptness and magnitude of this transition is governed by the crystal structure of VO2. The growth of thin VO2 films therefore requires substrate heating during deposition and, as well as the occasional need for additional post-deposition annealing. The processes that occur during annealing depend upon the deposition technique. However, the published reports related to these studies are rarely systematic and lack consistency. The annealing of thin nanocrystalline VO2+x films at temperatures above the melting point is reported here. Thin films were deposited onto a polycrystalline corundum substrate by means of radio-frequency reactive magnetron sputtering, with the thin film composition fine-tuned by applying negative substrate bias during deposition and proceeding with ex-situ control of the vanadium oxidation state. Post-deposition annealing causes recrystallization, which is in accordance with the V O phase diagram. No epitaxial or other substrate-induced processes were detected. However, the sharpest transition was attributed to the film possessing the most uniform grain size, as opposed to the film with the largest VO2 crystallites. The temperature dependency of the microwave radiation transmittance was investigated over the 8–18 GHz range, with the samples measured in free-space conditions. This was intended to reveal any frequency-dependent features, which can possibly appear as benefits or obstacles during the development of designs in the microwave range that are based on the VO2 films being studied.

Novel 3-(ethylthio)phenyl-substituted phthalocyanine and naphthalocyanine zinc complexes were synthesised with high yields. The Suzuki cross-coupling reaction provides selective approaches to the initial mono- or di- 3-(ethylthio)phenyl-substituted phthalonitriles. The complexes obtained were characterised by 1H nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Observation of the nuclear Overhauser effect was used for aromatic proton assignment. The correlation between the number of 3-(ethylthio)phenyl groups, the size of the π-system and the position of the Q-band was defined. Visualisation of the influence of increasing π-system size on aggregate size was provided by atomic force microscopy.

Iron powder particles were coated with a thin SiO 2 shell for protection of corrosion. Dynamic magnetic behavior of the as-synthesized material was studied in comparison with uncoated metal in terms of frequency dispersion of the microwave permeability and permittivity. A uniform 100-nm SiO 2 shell provides durable corrosion resistance to a 4.5-μm carbonyl iron powder. The shell was deposited through tetraethyl orthosilicate hydrolysis of technical grade chemicals. It was shown that the shell did not influence the magnetic properties of the iron powder. Electron microscopy, particle size analysis, and γ-resonance spectroscopy were applied in the study. The deposited SiO 2 decreased the microwave permeability value and prevented percolation conductivity in a composite with a paraffin wax dielectric matrix.

A model experiment was conducted in order to determine an interplay between inherent strains and electrochemical corrosion rate in nitrogen-doped iron thin films. 150 and 300 nm thick films, used in the experiment, were obtained by means of DC magnetron sputtering. In order to study the influence of substrate on inherent strains in metal, these films were deposited onto flexible polymer and rigid glass substrates. It was found, that the rigidity of the substrate increased the corrosion rate of thin iron films in a neutral electrolytic solution. It was proven using X-ray diffraction, that the greater rigidity was, the stronger were the internal strains within the films. That effect was especially pronounced in thinner films, where the increase in the rate of dissolution was accompanied by a localization of corrosion. Characteristics of electrochemical processes were measured using a three-electrode cell. The comparison of the films free surface energy was performed by measuring water contact angle.

There is a demand for ultra low-loss metal films with high-quality single crystals and perfect surface for nanophotonics and quantum information processing. Many researches are devoted to alternative materials, but silver is by far theoretically the most preferred low-loss material at optical and near-IR frequencies. Usually, epitaxial growth is used to deposit single-crystalline silver films, but they still suffer from unpredictable losses and well-known dewetting effect that strongly limits films quality. Here we report the two-step approach for e-beam evaporation of atomically smooth single-crystalline metal films. The proposed method is based on the thermodynamic control of film growth kinetics at atomic level, which allows depositing state-of-art metal films and overcoming the film-surface dewetting. Here we use it to deposit 35–100 nm thick single-crystalline silver films with the sub-100pm surface roughness and theoretically limited optical losses, considering an ideal material for ultrahigh-Q nanophotonic devices. Utilizing these films we experimentally estimate the contribution of grain boundaries, material purity, surface roughness and crystallinity to optical properties of metal films. We demonstrate our «SCULL» two-step approach for single-crystalline growth of silver, gold and aluminum films which open fundamentally new possibilities in nanophotonics, biotechnology and superconductive quantum technologies. We believe it could be readily adopted for the synthesis of other extremely low-loss single-crystalline metal films.

Reactive sputtering of permalloy typically reduces crystallite size in films, if the concentration of reactive gas is low. This advances magnetic properties: decreases coercivity and increases good in-plane magnetic anisotropy. But oxygen is rarely applied for this purpose. Here, peculiar deposition conditions, including the geometry of the vacuum deposition system and large polymer substrate, allowed for the deposition of supermalloy with unusually high admixture of oxygen. Evolution of both static and dynamic magnetic properties with an increase in oxygen concentration proved to be dealt with the balance between grain size, surface structure, disordering of atomic structure and internal stresses. The critical concentration when supermalloy shows indications of oxidation is 5% of O2. Coercivity, resistivity, roughness and ferromagnetic resonance frequency are the parameters that are most sensitive to oxidation.

Novel terbium(III), dysprosium(III), erbium(III) and lutetium (III) tetrapyrazinoporphyrazines with bulky 4-(tert-butyl)-phenyl groups, were obtained by metallation of porphyrazine ligand in high yields. The target complexes were identified by high-resolution matrix assisted laser desorption/ionization mass spectrometry, infrared and nuclear magnetic resonance spectroscopy. In nuclear magnetic resonance spectra, the proton signals demonstrate strong shifts for complexes with paramagnetic ions in comparison with lutetium one. The impact of peripheral (tert-butyl)phenyl groups and central ion nature on position of the main absorption bands in UV–Vis spectra was investigated. Two blends of gold nanoparticles (5 and 60 nm in diameters) and lutetium complex were prepared. The influence of the size of bare Au nanoparticles on core-shell structure of hybrid blends was investigated by transmission electron microscopy and atomic force microscopy. The nonlinear optical behavior of hybrid nanoparticles as well as initial lutetium (III) tetrapyrazinoporphyrazine was carried out using Z-scan measurements.

The effect of Ti substitution on the microwave and magnetostatic properties of nanostructured hexagonal BaFe12&minus, xTixO19 ferrite composites is studied. The microwave permeability is measured in the frequency range of 0.1&ndash, 22 GHz by a coaxial technique. An analysis of the magnetostatic data is made by the law of approach to saturation. The ferrimagnetic resonance frequencies calculated from the magnetostatic data are consistent with those obtained from the microwave measurements. The natural ferrimagnetic resonance frequencies are located in the frequency range of 15 to 22 GHz, depending on the substitution level x. An increase in the amount of substitution elements results in a low-frequency shift of the ferrimagnetic resonance frequency for samples with x &lt, 1. With x rising from 1 to 2.5, the resonance frequency increases. The results of the study demonstrate that the tailored optimization of the nano-structure of a functional material is a robust tool to fine-tune its microwave magnetic properties. The ferrites under study are promising materials to be applied as functional coatings intended to control electromagnetic interference in microwave devices.

In this letter, microwave and magnetostatic measurements of single- and multilayer Permalloy films are made to find physical reasons causing the decrease of the microwave permeability of the films with increase in film thickness. The permeability is measured in the frequency range of 0.1–10 GHz by a coaxial technique. From the measured permeability, a contribution to the effective field from the magnetoelastic effect is determined. The decrease of microwave permeability in thick films is shown to arise mainly due to the perpendicular magnetic anisotropy rather than from the effect of eddy currents, as is frequently suggested. It is also shown that both these effects are reduced in multilayer films comprising alternating magnetic and dielectric layers. Therefore, such films are promising materials for developing magnets that possess high permeability at high frequencies.

Novel heteroleptic naphthalo-phthalocyaninates of lutetium possessing a symmetrical substituted naphthalocyanine deck were synthesized on the basis of two preformed synthetic blocks: naphthalocyanine ligand and lutetium phthalocyaninates. The compounds obtained were characterized by (1)H NMR and high-resolution MALDI-TOF/TOF mass spectrometry. The correlation between the nature of the substituents and the spectral properties of the target complexes was determined by the introduction of electron-donating (aryl-, aryloxy-) or electron-withdrawing (chloro-) substituents into the phthalocyanine deck. In addition, the nature of peripheral substituents was shown not to affect drastically the phthalocyanine conductivity and activation energy. Conductivity properties depend on thin film morphology which, in turn, relies on intermolecular π-π interactions.

During last 20 years, great results in metamaterials and plasmonic nanostructures fabrication were obtained. However, large ohmic losses in metals and mass production compatibility still represent the most serious challenge that obstruct progress in the fields of metamaterials and plasmonics. Many recent research are primarily focused on developing low-loss alternative materials, such as nitrides, II–VI semiconductor oxides, high-doped semiconductors, or two-dimensional materials. In this work, we demonstrate that our perfectly fabricated silver films can be an effective low-loss material system, as theoretically well-known. We present a fabrication technology of plasmonic and metamaterial nanodevices on transparent (quartz, mica) and non-transparent (silicon) substrates by means of e-beam lithography and ICP dry etch instead of a commonly-used focused ion beam (FIB) technology. We eliminate negative influence of litho-etch steps on silver films quality and fabricate square millimeter area devices with different topologies and perfect sub-100 nm dimensions reproducibility. Our silver non-damage fabrication scheme is tested on trial manufacture of spasers, plasmonic sensors and waveguides, metasurfaces, etc. These results can be used as a flexible device manufacture platform for a broad range of practical applications in optoelectronics, communications, photovoltaics and biotechnology.

Selective synthetic approaches to novel single- and multiple-decker terbium(III) phthalocyaninates, bearing peripheral phenyl groups, were developed. The compounds were identified by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, Fourier-transform infrared and UV–Vis spectroscopy. From the X-ray data for initial 1,2-dicyano-4,5-diphenylbenzene it was shown that phenyl groups are not in the same plane, and dihedral angle between them equals 64°. Strong upfield shifts of the aromatic proton signals up to −131.62 ppm in the case of a triple-decker complex were found in the nuclear magnetic resonance spectra due to paramagnetic nature of terbium(III) ion. Stronger intramolecular interactions are observed for the sandwich-type phenyl-substituted terbium complexes comparing to tert -butyl-substituted analogs, earlier described in literature. In the case of the double-decker compound, this results in 142 nm hypsochromic shift of the intervalence absorption band. DC conductivity measurements were carried out for terbium bis phthalocyaninate. The formation of the ring-shaped self-assembled aggregates with a diameter of 400 nm was observed in thin solid films of the prepared terbium(III) compounds by atomic force microscopy.

Magnetron sputtered nanocrystalline thin Fe70Co30 metal and (Fe70Co30)95(SiO2)5 composite films show a differently broadened Mossbauer sextet, which is interpreted as an increase in CsCl-type solid solution ordering degree for the composite film. It is suggested that the effective magnetic field at iron nuclei increases by 15 kOe when an Fe atom is substituted by Co in the first coordination sphere. The ordering degree and the composite structure are shown to vary the lattice parameter by up to 0.5%.

The tailored production of thin Co films of 50 nm thick with ferromagnetic resonance frequency in a range from 2.9 to 7.3 GHz using the DC magnetron sputtering is reported. The ferromagnetic resonance frequency, coercivity, effective magnetic field and nanocrystalline structure parameters are shown to be governed by the Co deposition rate. For this investigation, FMR, VSM and TEM techniques were used.

An increase in the ferromagnetic resonance frequency from 3 to 5.5 GHz is discovered in thin Co films during an increase in the crystallite size from 6 to 70 nm. The structure change is achieved by increasing the deposition rate from 4.2 to 7.1 nm/min in direct-current magnetron sputtering. The Co films possess a uniaxial crystallographic texture. The orientation of the texture axis varies with a variation in deposition parameters, which causes changes in the in-plane magnetic anisotropy. A model to describe the discovered changes is proposed.

Iron film surfaces have been studied after their chemical treatment in a magnetic field. The chemical treatment of a metal leads to the appearance of a relief image that is interpreted as a “photograph” of magnetic scattering fields. The morphology of the relief image formed is shown to correlate with the domain structure of a magnetic film. The magnetochemical effect revealed allows the visualization of the dependence of the scattering field distribution at the sample surface on external magnetic field.