We show that the real-time singularities found in the analytically continued double-well instanton are not an inherent feature of Minkowski tunneling, but a degenerate limiting phenomenon. Using a linear homotopy between a triple-well and a double-well potential, we construct a family of potentials, parametrized by p∈(0,1), whose real-time (α=0) instanton solutions are everywhere regular and bounded. For any Wick rotation angle α∈(0,π/2), we prove that regularity is generic but not universal. There exists a countably infinite, closed-form family of potential parameters {p_s,k(α)}_k≥0 at which the instanton develops exactly two real-time singularities, never more. In the strict double-well limit (p→1) taken at α=0, these collapse into the infinite singular comb found by Cherman and Ünsal. By solving the complexified equations of motion in terms of Weierstrass elliptic functions, we trace this comb to classical imaginary turning points receding to ±i∞, giving a unified geometric and algebraic account of when, and exactly how often, real-time instantons become singular.

A methodology to model the percolated conductive network in nanoparticle-based thin films, synthesized by means of a magnetron-based gas aggregation source, was developed and validated. Two differently sized copper oxide nanoparticles were produced by varying the diameter of the exit orifice. Comprehensive characterization of these films was performed using scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering and X-ray diffraction to determine particle morphology, size distribution, porosity, vertical density profiles, and phase composition. Using the experimental data, virtual films were generated through a data-driven stochastic 3D microstructure model that is based on a sphere packing algorithm, where the particle size distribution, porosity and vertical density profile are taken into account. The generated 3D structures have been then refined to cover the effect of oxidation of as-deposited nanoparticles and non-zero roughness of real films. A computational model incorporating a simplified adsorption model was developed to simulate the effects of oxygen adsorption on the surface conductivity of the nanoparticles. Then, the electrical conductivity of the percolated networks in these virtual structures was computed using the finite element method for various partial oxygen pressures. Simulated resistivity values were compared with experimental measurements obtained from four-point probe resistivity measurements conducted under varying oxygen partial pressures at 150°C A discussion of the validity of the model and its ability to cover qualitatively and quantitatively the observed behaviour is included.

This study explores the feasibility of deposition of composite films based on nanoparticles (NPs) using a magnetron-based gas aggregation source of NPs. First, we investigate the deposition conditions and properties of the individual components of the composite films, namely, NPs prepared using Cu and W targets. We thoroughly discuss that the generation of NPs might be more efficient in the Ar atmosphere in the case of W target due to an enhanced direct emission of NP seeds from the target and/or a longer lifetime of the seeds in the plasma. To operate reasonable fluxes of NPs for both targets, O2 was added into the gas mixture. Lower O2 flow rates promote enhanced seed formation of NPs, while higher flow rates exhibit a dominant target poisoning effect, reducing the flux of NPs. We demonstrate that a fine-tuning of O2 flow rate allows us to control the resulting crystal structure of the NPs. Fully oxidized NPs were produced at O2 flow rates of 1.30sccm and 1.50sccm for Cu and W targets, respectively. Subsequently, CuO/WO3 composite films were prepared using our in-house-built software as alternating NPs-based layers. To demonstrate the capabilities of the deposition technique, three different CuO/WO3 multilayers were prepared, each with a specific thickness of the individual layers (80nm, 40nm, and 10nm, which corresponds to a monolayer of NPs). Scanning electron microscopy imaging shows well-defined layers with the intended thickness. In addition, XRD analysis confirms that all three multilayers exhibit practically identical patterns, indicating the same volumetric ratio of CuO and WO3 NPs in the investigated films.

We disclose a serious deficiency of the Baym-Kadanoff construction of thermodynamically consistent conserving approximations. There are two vertices in this scheme: dynamical and conserving. The divergence of each indicates a phase instability. We show that each leads to incomplete and qualitatively different behavior at different critical points. The diagrammatically controlled dynamical vertex from the Schwinger-Dyson equation does not obey the Ward identity and cannot be continued beyond its singularity. The standardly used dynamical vertex alone cannot, hence, conclusively decide about the stability of the high -temperature phase. On the other hand, the divergence in the conserving vertex, obeying the conservation laws, does not invoke critical behavior of the spectral function and the specific heat. Moreover, the critical behavior of the conserving vertex may become spurious in low -dimensional systems. Consequently, the description of the critical behavior of correlated electrons becomes consistent and reliable only if the fluctuations of the order parameter in the conserving vertex lead to a divergence coinciding with that of the dynamical one.

Our investigation was concentrated on two basic challenges in the field of hard protective coatings prepared by magnetron sputtering: (1) Toughness and resistance to cracking (TRC) and (2) Flexible Hard Coatings with high thermal stability (TS). While results of investigation of TRC were already comprehensively published in a chapter of the book Thin Films and Coatings, Toughening and Toughness Characterization [1], results of the investigation of TS have not been comprehensively published yet. These results are described in detail in this new article. The choice and the presentation of the material in this article reflect the interests and perspectives of the principal author. The paper reports on the enhanced hardness and thermal stability of nanocomposite coatings, and on the formation of the X-ray amorphous coatings with thermal stability and oxidation resistance above 1000 degrees C and of flexible hard coatings. Reported results can be used in the development of the flexible ceramic coatings, in the surface strengthening of brittle materials, and in the prevention of (i) cracking of the functional coatings and (ii) the crack formation on the surface of bent materials. It is shown that the energy delivered into the flexible hard coatings during their growth plays a key role in their formation. Special attention is devoted to formation of coatings with unique, fully reproducible properties and to new technology based on highly non-equilibrium processes at the atomic level. Special attention is also devoted to the speed of cooling of hard nanocoatings and to its effect on their thermal stability at high temperatures reaching up to 2000 degrees C. The key role of interdisciplinary insights in the development of new advanced hard coatings is also discussed. In conclusion trends in the next development of new advanced hard nanocoatings are indicated.

The reversible semiconductor-to-metal transition of vanadium dioxide (VO2) makes VO2-based coatings a promising candidate for thermochromic smart windows, reducing the energy consumption of buildings. We report on a scalable sputter deposition technique for fast preparation of strongly thermochromic YSZ/ V0.986W0.014O2/YSZ coatings, where YSZ denotes Y-stabilized ZrO2, on conventional soda-lime glass at a rela-tively low substrate surface temperature (350 degrees C) and without any substrate bias voltage. The thermochromic V0.986W0.014O2 layers and the antireflection YSZ layers were deposited using a controlled high-power impulse magnetron sputtering of a single V-W and Zr-Y target, respectively. A coating design utilizing a second-order interference in the YSZ layers was applied to increase both the integral luminous transmittance (Tlum) and the modulation of the solar energy transmittance (Delta Tsol). We present the phase composition (X-ray diffraction) and microstructure (high-resolution transmission electron microscopy) of the coatings and their optical properties (spectrophotometry and spectroscopic ellipsometry). The YSZ/V0.986W0.014O2/YSZ coatings exhibit a transition temperature of 33-35 degrees C with Tlum = 64.5% and Delta Tsol = 7.8% for a V0.986W0.014O2 thickness of 37 nm, and Tlum = 46.1% and Delta Tsol = 13.2% for a V0.986W0.014O2 thickness of 67 nm. The results constitute an important step to a cost-effective and high-rate preparation of large-area thermochromic VO2-based coatings for future smart-window applications.

The chapter describes sputtering technologies of flexible hard nanocoatings based on strongly non-equilibrium processes at an atomic level. Six technologies are briefly described: (1) The low-temperature sputtering of coatings, (2) the sputtering of beta-phase coatings, (3) the sputtering of superhard metallic coatings, (4) the sputtering of transition metal (TM) overstoichiometric nitride and dinitride coatings, (5) the sputtering of heterostructural alloy coatings, and (6) the hardness of hard nanocoatings. At the end, the present state of knowledge in this field is summarized and the trends of next development are indicated.

The article reports on the mechanical properties of alloy films prepared by magnetron sputtering. Cracking is a great drawback of alloy films because it strongly limits many of their practical applications. It is shown that hard alloy films resistant to cracking must be superelastic and exhibit a high ratio H/E* ≥ 0.1; here H is the hardness and E* is the effective Young's modulus of the film. As examples, mechanical properties of the Si-based hard alloy films with enhanced resistance to cracking are given. Furthermore, the effect of the addition of Si and N into single element Mg films on the film mechanical properties and its relation to the changes of the material homologous temperature is investigated.

High-power impulse magnetron sputtering of a Ta target in precisely controlled Ar+O2+N2 gas mixtures was used to prepare amorphous N-rich tantalum oxynitride (Ta–O–N) films with a finely varied elemental composition. Postdeposition annealing of the films at 900°C for 5 min in vacuum led to their crystallization without any significant change in the elemental composition. The authors show that this approach allows preparation of a Ta–O–N film with a dominant Ta2N2O phase of the bixbyite structure. As far as the authors know, this phase has been neither experimentally nor theoretically reported yet. The film exhibits semiconducting properties characterized by two electrical (indirect or selection-rule forbidden) bandgaps of about 0.2 and 1.0 eV and one optical (direct and selection-rule allowed) bandgap of 2.0 eV (suitable for visible-light absorption up to 620 nm). This observation is in good agreement with the carried out ab initio calculations and the experimental data obtained by soft and hard X-ray photoelectron spectroscopy. Furthermore, the optical bandgap is appropriately positioned with respect to the redox potentials for water splitting, which makes this material an interesting candidate for this application.

The ion-flux characteristics at a substrate position and the corresponding discharge characteristics were investigated during controlled low-temperature (300 degrees C) reactive high-power impulse magnetron sputtering (HiPIMS) depositions of thermochromic VO2 films onto conventional soda-lime glass substrates without any substrate bias voltage and without any interlayer. It was shown that the phase composition of the films correlates with the (V+ + V2+) ion fraction and the (V+ + V2+):(2O(2)(+) + O+) ion ratio in the total ion flux onto the substrate. Setting the amount of oxygen in the gas mixture allowed us to control not only the phase composition of the films but also their crystallinity. It was found that an appropriate composition of the total ion flux and high ion energies (up to 50eV relative to ground potential) support the crystallization of the thermochromic phase in the VO2 films. We achieved a high modulation of the transmittance at 2500nm (between 51% and 8%) and of the electrical resistivity (changed 350 times) for a 88nm thick VO2 film.

The letter reports on the surface hardening of bulk soft metal materials by protective coatings made of the same metal as bulk but with up to 6 times higher hardness than that of the bulk material. This surface hardening is demonstrated by covering of the Ti substrate with a low hardness H-bulk approximate to 5 GPa by a 1200 nm thick Ti coating with a high hardness H-coating approximate to 30 GPa. The protective hard Ti coatings were sputtered by a new sputtering technology based on extremely high pressures (>= 1000 GPa), high temperatures exceeding the melting temperature T-m of the coating material and extremely high cooling rate of the created coating (>= 10(10) K/s). The principle of this technology realized at an atomic level is described in detail. (C) 2019 Elsevier B.V. All rights reserved.

This article reports on the formation of strongly overstoichiometric ZrNx>1 and Ti(Al, V)N-x>1 coatings by reactive magnetron sputtering. Problems in the formation of overstoichiometric coatings and possible ways to form strongly overstoichiometric TMNx>1 nitride coatings up to TMNx=2 dinitride coatings are discussed; here, TM are transition metals such as Ti, Zr, Mo, Ta, Nb, W, etc. The coating stoichiometry x = N/TM strongly influences its electrical and mechanical properties. The creation and properties of reactively sputtered ZrNx coatings were investigated. It was found that (1) the electrical resistivity of the ZrNx coating varies with increasing x from well electrically conducting films with x <= 1 through semi-conducting films with x ranging from 1 <= 1.26 to non-conductive with x >= 1.3, showing that the stoichiometry x is a strong parameter which enables to control an electric conductivity of the coating in a wide range, (2) electrically conductive coatings with x <= 1 are harder than the semiconducting and electrically insulating coatings, and (3) the ZrN2 dinitride film cannot be created due to the formation of a Zr3N4 phase whose formation enthalpy is greater than that of a ZrN2 phase. Further, it is shown that the main problem in the formation of strongly overstoichiometric TMNx>1 and dinitride TMN2 coatings is a strong increase of ionization of the nitrogen sputtering gas to achieve a necessary high ratio N/TM > 1. Trends enabling the mastery of formation of the TMN2 dinitride coatings are briefly outlined. (C) 2018 The Japan Society of Applied Physics

The article reports on the formation of high-temperature β-phase films prepared by magnetron sputtering. The principle of formation of the β-phase films is explained. It is shown that the β-phase films are composed of elements that crystallize in different crystal structures and are a novel class of heterostructural films. The properties of the β-phase films are unique and they are controlled by the crystal structures in which the elements contained in the films crystallize. It means that there are three basic parameters which decide on the resulting properties of the β-phase films: (1) the energy delivered into the film during its growth, (2) the elemental composition of the film and (3) the crystal structure of elements or phases in the film. The existence of many possible combinations of the crystal structure of elements and/or phases in the film makes it possible to develop new advanced heterostructural films with new unique properties. It is a great challenge for the further progress in the field.

Zgodovina nas uci, da je clovek eden najpomembnejsih dejavnikov v podjetju. Vcasih so delavce postavili na delovno mesto in jim dali delo brez razlage in brez vsake pomoci. Danes pa temu vec ni tako, saj lahko vidimo, da velika vecina podjetij veliko vlaga v izobraževanje in ucenje svojih zaposlenih. Danes cloveku ne damo vec samo dela, temvec ga na to delo tudi temeljito pripravimo. Ponudimo mu izobraževanje, ki se najbolj prilega njegovemu profilu ter ga razvijamo tako, da lahko podjetju prinese cim vec novih znanj. Delodajalec si svojega zaposlenega prilagodi glede na svoje podjetje tako, da lahko zanj cim vec stori oziroma mu cim vec doprinese. Ne le v financnem smislu, temvec imamo v mislih tudi znanja, ki jih nekdo prinese v organizacijo. V diplomskem delu bomo govorili o managementu znanja in prenosu znanja med nadrejenimi in podrejenimi glede na stil vodenja, ki se uporablja v organizaciji. Opredelili bomo proces vodenja, vodjo, njegove naloge in lastnosti uspesnega vodje. Prav tako bomo razložili, zakaj je pomemben management znanja in kako se s tem soocajo podjetja v praksi. Podrobneje bomo opredelili aktualne stile vodenja in ocenili prenos znanja v vsakemu izmed njih. Posebej bomo preucili okvire mentorskega stila vodenja ter njegovo implementacijo v podjetju Etrad3 d.o.o. Izvedli bomo intervjuje z nadrejenimi in podrejenimi v omenjeni organizaciji ter tako pridobili informacije o njihovem dojemanju prenosa znanja. Iz teh podatkov bomo analizirali management znanja v podjetju in pripravili predloge za izboljsanje stanja v podjetju in predloge za uporabo v praksi. Z raziskavo smo ugotovili, da prihaja v mentorskem stilu vodenja do boljsega prenosa znanja kot v ostalih obravnavanih stilih. To smo potrdili tako z teoreticno vsebino, kot tudi z raziskavo v izbranem podjetju. Ugotovili smo, da ima najvecji vpliv na prenos znanja med nadrejenimi in podrejenimi motiviranost vsakega posameznika.

This letter reports on the formation of hard TiN2 dinitride films prepared by magnetron sputtering. TiN2 films were reactively sputtered in an Ar + N2 gas mixture using a pulsed dual magnetron with a closed magnetic field B. The principle of the formation of TiN2 films by magnetron sputtering is briefly described. The stoichiometry x = N/Ti of the TiNx films was controlled by deposition parameters, and its maximum value of x = 2.3 was achieved. For the first time, a possibility to form the TiN2 dinitride films by magnetron sputtering has been demonstrated. The mechanical properties of sputtered films were investigated in detail.

This article reports on formation of flexible hydrophobic ZrN films with enhanced resistance to cracking prepared by reactive magnetron sputtering. It is shown that (1) the hydrophobicity of the ZrN films is their intrinsic property and all sputtered ZrN films are hydrophobic and (2) the flexibility of the ZrN films with enhanced resistance to cracking is achieved by an optimization of their mechanical properties only. The flexible ZrN films are typical representatives of carbon-free low-electronegativity metal compounds.

We show here that intrinsic hydrophobicity of HfO2 thin films can be easily tuned by the variation of film thickness. We used the reactive high-power impulse magnetron sputtering for preparation of high-quality HfO2 films with smooth topography and well-controlled thickness. Results show a strong dependence of wetting properties on the thickness of the film in the range of 50–250 nm due to the dominance of the electrostatic Lifshitz-van der Waals component of the surface free energy. We have found the water droplet contact angle ranging from ≈120° for the thickness of 50 nm to ≈100° for the thickness of 2300 nm. At the same time the surface free energy grows from ≈25 mJ/m2 for the thickness of 50 nm to ≈33 mJ/m2 for the thickness of 2300 nm. We propose two explanations for the observed thickness dependence of the wetting properties: influence of the non-dominant texture and/or non-monotonic size dependence of the particle surface energy.

Nd-, Zr-, Laand Ycompound films were prepared by dc reactive magnetron sputtering in an Ar+O 2 (Nd-O, La-O and Zr-O) or Ar+N 2 (Nd-N, Zr-N, Y-N) gas mixture. While the total pressure, temperature and target power were held constant, the partial pressure of the reactive gas was varied in the range from 20% to 80%. In this work hydrophobic (Water Droplet Contact Angle (WDCA) and surface free energy) and mechanical (hardness, effective Young’s modulus and elastic recovery) properties were studied. Hydrophobicity of the sputtered films was measured by the sessile drop method with polar and non-polar testing liquids. The most often used van Oss-Good-Chaudhury approach based on the Lifshitz-van der Waals/acid-base theory was selected for calculating of surface free energy. Interactions with testing liquids demonstrate the non-polar nature of all the surfaces tested. We found out that: (1) Values of WDCA range from 94 o (Zr-O) to 106 o (Y-N). (2) Nitrides give rise to systematically higher values of WDCA in comparison with oxides, which we attribute to a difference in the electronic structure leading to a different number of bonds with water molecules. (3) Reduced water chemical adsorption by the prepared surfaces allows to obtain higher values of WDCA in comparison with WDCA for most of transition metals compounds. (4) Hardness H of the prepared films ranges from 8 GPa (La-N) to 18 GPa (Zr-N). Zr and Nd compounds with values of the effective Young’s modulus E* in the range 119÷144 GPa show high values of the H/E* ratio = 0.101÷0.124 and of the elastic recovery W e = 67÷73%. On the other hand La and Y compounds with E* in the range 128÷138GPa show low values of the H/E* ratio ≈ 0.08 and of W e = 43÷57 %.

Hydrophobic materials capable of withstanding harsh conditions are required for various applications. Here, we show that oxides and nitrides of various low-electronegativity metals are hydrophobic hard ceramics. We attribute their hydrophobicity to low Lewis acidity of the low-electronegativity cations implying a low ability of the cations on the surface to form coordinate bonds with water oxygen anions. Furthermore, we observe a systematically stronger hydrophobic behavior of nitrides compared with the corresponding oxides, which we attribute to nitrogen being a poorer Lewis base than oxygen due to a reduced number of lone pairs of electrons, implying a lower ability of nitrogen anions on the surface to form hydrogen bonds with water hydrogen cations. Most of the oxides and nitrides investigated exhibit high values of hardness. Therefore, oxides and nitrides of low-electronegativity metals should find application as hydrophobic materials in harsh conditions.