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In KTaO3:Er crystals, we observed a temperature shift, unusual for rare earth impurities, for narrow zero-phonon luminescence lines, due to the 4S3/2 → 4I13/2, 4F9/2 → 4I15/2, and 4S3/2 → 4I15/2 transitions in Er3+ impurity ions. The magnitude of the shifts turned out to be comparable with the large shifts of the R lines of the Cr3+ luminescence in SrTiO3:Cr and KTaO3:Cr crystals, that is, substantially larger than that for the three-charged rare earth ions usually observed in the f–f luminescence spectra in ionic crystals.

In this work, we determine the dielectric functions of multi-target, reactively sputtered Ba(Zr0·2Ti0.8)O3 by spectroscopic ellipsometry in the photon energy range from 0.8 to 8.7 eV. Based on this data, we discuss the interband transition energies and the spectral dependencies of the refractive index and the absorption coefficient.

Inversion recovery with electron spin-echo detection has been used to study the electron spin-lattice relaxation rates 1 / T 1 for transition metal impurities in heavily cobalt-doped hydrothermally grown ZnO single crystals. The relaxation dynamics of Co 2 + ions dominates the phonon bottleneck effect in the Orbach-Aminov process, which involves the modulation of the zero-field-splitting tensor. The relaxation mechanism may be treated in terms of phonon heating with fast rate of energy pump from Co 2 + spins into the lattice phonon modes. The measurements reveal the cross-relaxation process in which the single Co 2 + ions cross-relax to exchange-coupled clusters of cobalt ions. The higher temperature relaxation of Co 2 + indicates an additional Orbach-Aminov process via a state of ∼ 226 cm − 1 above the ground state Kramers doublet. It is shown that in this system Co 2 + ions play a role of the rapidly relaxing centers, strongly mediating the spin-lattice relaxation of the other transition metal impurities, such as Mn 2 + and Fe 3 +.Inversion recovery with electron spin-echo detection has been used to study the electron spin-lattice relaxation rates 1 / T 1 for transition metal impurities in heavily cobalt-doped hydrothermally grown ZnO single crystals. The relaxation dynamics of Co 2 + ions dominates the phonon bottleneck effect in the Orbach-Aminov process, which involves the modulation of the zero-field-splitting tensor. The relaxation mechanism may be treated in terms of phonon heating with fast rate of energy pump from Co 2 + spins into the lattice phonon modes. The measurements reveal the cross-relaxation process in which the single Co 2 + ions cross-relax to exchange-coupled clusters of cobalt ions. The higher temperature relaxation of Co 2 + indicates an additional Orbach-Aminov process via a state of ∼ 226 cm − 1 above the ground state Kramers doublet. It is shown that in this system Co 2 + ions play a role of the rapidly relaxing centers, strongly mediating the spin-lattice relaxation of the oth...

Electron paramagnetic resonance studies of the impurity Fe$^{3+}$ and Mn$^{4+}$ centers indicate that the symmetry of the crystal structure of millimeter-scale strontium titanate plates above 105 K lowers in the bulk from cubic to tetragonal, different from that of the conventional low-temperature antiferrodistortive phase. It is shown that the effect does not originate from the residual stress; its magnitude (observed tetragonal distortion) and particular manifestations depend on plate orientation, surface quality and the geometry of a sample. Peculiarities of the observed phenomenon are presented and possible scenario of its realization is discussed., 14 pages, 4 figures

The f–f absorption and emission spectra of Er3+ impurities were observed and identified in KTaO3 and K1 – xLixTaO3 single crystals. It was shown that Li off-centers related random fields markedly influence intensity, width and position of zero-phonon lines. The detail analysis of the absorption spectra obtained allowed one to determine energies of the Stark sublevels of excited states for Er3+ dominant centers of noncubic symmetry.

The electron spin echo detected inversion recovery technique at the Q-band frequency was used to characterize spin diffusion effects in spin-lattice relaxation of compensating Fe3+ impurities in n-type doped GaN crystals. It was found that the selective saturation can be achieved in the GaN:Fe3+ system due to magnetization transfer based on the spin flip-flop cross-relaxation processes. The temperature dependence of 1/T1 can be explained by direct spin-phonon processes ( ∼ T) below 25 K and by Raman two-phonon processes ( ∼ T 9) at higher temperatures. Spin diffusion in this system is characterized by an additional cross-relaxation rate which is weakly temperature-dependent below 25 K. The transferred hyperfine interactions of Fe3+ centers with gallium and nitrogen neighbor nuclei were resolved using pulsed-electron nuclear double resonance. A comparative analysis of quadrupole interactions indicates the essential increase in the electric field gradients on the nearest nitrogen and gallium shells.

We have derived the analytical expressions for the diffusion coefficients describing the particle diffusion on different heterogeneous lattices. It occurs that these expressions can be used for description of the particle diffusion on the patchwise lattices. The coverage dependencies of the center-of-mass and Fickian diffusion coefficients obtained for some patchwise lattices by the Monte Carlo simulation can be perfectly fitted by these expressions. The good coincidence of the numerical data with the theoretical results demonstrates the applicability of the analytical expressions for the wide class of heterogeneous lattices.

The scratch test is a well-established instrumental method for assessment of the cohesive-adhesive parameters of thin films and coatings. Its evaluation is classically performed using the microscopic analysis of residual scratch and the indenter depth-change record. However, these analysis methods can be insufficient for detection of the very first film-to-substrate adhesion failures. To overcome this difficulty, an independent method of detection of acoustic emission signals can be employed. The detection system of acoustic emission, developed in our laboratory, utilizes a special holder and continuous recording during the whole scratch test. The piezoelectric sensor with 2 MHz sampling rate and sophisticated software allow a thorough post-process analysis of recorded acoustic emission signal. Failure events can be observed on microsecond scale and their frequency spectra can be evaluated.The demonstration of the acoustic emission probe detection capability is performed on the model layers. Comparison of the acoustic emission record to residual scratch image and indenter depth-change record shows a detection sensitivity of the method. Analysis of failure mode dynamics at the appropriate time scale is outlined.

The chromium doped SrTiO3 nanopowders with particles size of 100, 50, 20 nm sizes have been synthesized and studied by Electron Paramagnetic Resonance (EPR). Along with chromium impurity it was found the powder contained small concentration of manganese as a residential impurity. Mn4+ ions on Ti4+ lattice sites were identified, with spin-Hamiltonian parameters closed to even in the bulk material. It was found that the linewidth depends on particle size. This effect may be traced back to changes of the small parameter of fine structure D due to its dependence on the particle size of the individual nanocrystallite. It seems, the most of Cr3+ ions did not substitute for Ti4+ and form some phase at the surface of SrTiO3 particles.

Large area film deposition was performed by means of multitarget reactive magnetron sputtering from metallic targets (Pb, Ti, Zr) with a diameter of 200 mm onto Cu-coated Kapton® HN substrates. High-power pulse sputtering has been employed for the Zr-target (or alternatively for the Ti-target). Film composition profiles were evaluated by XPS and RBS. Piezoelectric properties were investigated by PFM.

The diffusion of particles adsorbed on patchwise surfaces is investigated in the framework of a lattice-gas model. We propose the analytical expressions for the center-of-mass and Fickian diffusion coefficients. The theoretical dependencies are compared with the numerical data obtained by the kinetic Monte Carlo simulations for three different patchwise lattices. The good coincidence of the theoretical dependencies and the numerical data corroborates the validity of the approach developed to describe the particle migration on such lattices.

We used optical ellipsometry to study and elucidate the nature of the negative thermo-optic effect in KTaO3 single crystals, which consists of an increasing refraction index magnitude in the visible region upon cooling (dn/dT < 0). The optical constant functions were determined within the 1–6 eV region. The energies of the band edge indirect and direct optical transitions and their temperature evolutions in the region of 80–300 K were carefully investigated. The absorption edge in the region of the lowest indirect R → Γ optical transitions, 3.7–4.2 eV, was observed to shift to higher energies upon cooling. Simultaneously, an increase and ‘red shift’ of the optical absorption in the region of the direct X5'upper → X3 transitions (4.3–4.8 eV) were observed, which should be responsible for the nature of the observed negative thermo-optics in KTaO3.

Correct description of optical properties of layers of disordered interacting nanoparticles is the problem. Contrary to volumes of nanocomposites, when standard models of effective-medium approximations (EMA) work well, two-dimensional case of layers has intrinsic anisotropy, which influences interparticle interactions. The deficiency of standard Maxwell-Garnett model in the application to the ellipsometry of layers of gold nanoparticles is demonstrated. It demands the modification of EMA models and one way of this is considered in this paper. Contrary to existing 2D models with phenomenological parameters, the proposed Green function approach uses the same number of parameters as standard 3D EMA models for explicit calculations of effective parameters of layers of disordered nanoparticles.

The spin relaxation dynamics of Ce$^{3+}$ ions in heavily cerium-doped YAG crystals is studied using pulse-electron paramagnetic resonance and time-resolved pump-probe Faraday rotation. Both techniques address the 4$f$ ground state, while pump-probe Faraday rotation provides also access to the excited 5$d$ state. We measure a millisecond spin-lattice relaxation time $T_1$, a microsecond spin coherence time $T_2$ and a $\sim 10$ ns inhomogeneous spin dephasing time $T_2^*$ for the Ce$^{3+}$ ground state at low temperatures. The spin-lattice relaxation of Ce$^{3+}$ ions is due to modified Raman processes involving the optical phonon mode at 125 cm$^{-1}$. The relaxation at higher temperature goes through a first excited level of the $^{2}$F$_{5/2}$ term at about $\hbar \omega \approx 228$ cm$^{-1}$. Effects provided by the hyperfine interaction of the Ce$^{3+}$ with the $^{27}$Al nuclei are observed.

Results of a detailed study of optical absorption and photoluminescence of slightly erbium-doped (~50 ppm) strontium titanate (SrTiO 3 ) single crystals are presented. This study allowed us to specify the structure of energy levels that determine the main internal optical transitions within the 4f 11 electron configuration of Er 3+ ions in SrTiO 3 :Er crystals at temperatures below the transition from cubic to tetragonal phase. The numbers of energy levels of the studied multiplets obtained at 2 K correspond exactly to the theoretically expected numbers of crystal field levels for multiplets of only one type of Er 3+ centers with non-cubic symmetry. Experimental results indicate that Er 3+ ions most probably substitute for Sr 2+ ions acting in SrTiO 3 as ionized donors. Such location of Er 3+ ions is consistent with both n-type conductivity and substantial free charge carrier absorption in the infrared spectral region observed in the studied SrTiO 3 :Er single crystals at room temperature.

We report on optical absorption and EPR spectroscopy studies of low Er doped (50 ppm) SrTiO3 single crystals. In the region of 400–650 nm a set of optical intra-configurational f–f transitions from the 4I15/2 ground state to the excited 4F9/2, 4S3/2, 2H11/2, and 2H9/2 Stark sublevels of the Er3+ impurity ions were observed and identified. At T = 2 K the number of registered optical transitions evidences the presence of only one type of Er3+ centers with non-cubic symmetry. The system of the energy levels for Er3+ excited states is determined. The X-band EPR spectra at 5.2 K revealed the rhombic symmetry of Er3+ impurity centers. The components of a rhombic g-tensor were defined. It was suggested that Er ions substitute Sr ions in A-sublattice sites.

The nature of intrinsic and impurity point defects in lead zirconate titanate (PZT) ceramics has been explored. Using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) methods, several impurity sites have been identified in the materials, including the Fe 3+ -oxygen vacancy (VO) complex and Pb ions. Both of these centers are incorporated into the PZT lattice. The Fe 3+ -V paramagnetic complex serves as a sensitive probe of the local crystal field in the ceramic; the symmetry of this defect roughly correlates with PZT phase diagram as the composition is varied from PbTiO 3 to PbZrO 3 . NMR spectra 207 Pb in PbTiO 3 , PbZrO 3 , and PZT with iron content from 0 to 0.4 wt% showed that increasing the iron concentration leads to a distortion of the crystal structure and to improvement of the electrophysical parameters of the piezoceramics. This is due to the formation of a phase which has a higher symmetry, but at high concentrations of iron (>0.4 wt%), it leads to sharp degradation of electrophysical parameters.

The electron-spin-resonance (ESR) spectra of SrTiO3:Mn single crystals have been investigated. Results unambiguously indicate that the impurity center formed by an Mn2+ ion has a dynamic nature. In the high temperature range (T > 100 K), ESR spectra of Mn2+ ions reveal cubic symmetry; the spectrum is found to broaden significantly with a decrease in temperature. Upon cooling to T < 10 K, low-symmetry centers of Mn2+ ions with a strong orientational dependence emerge in the spectra. Temperature evolution of the ESR spectrum can be described within the model of a dynamic off-center Mn2+ ion substituting for the Sr2+ ion, with a transition to the static regime at low temperatures with an average localization energy of ∼2.4 ± 0.4 meV for Mn2+ centers due to random deformations.

The trivalent chromium centers were investigated by means of electron paramagnetic resonance (EPR) in SrTiO 3 single crystals grown using the Verneuil technique. It was shown that the charge compensation of the Cr 3+ - V O dominant centers in octahedral environment is due to the remote oxygen vacancy located on the axial axis of the center. In order to provide insight into spin-phonon relaxation processes the studies of axial distortion of Cr 3+ - V O centers have been performed as function of temperature. The analysis of the trigonal Cr 3+ centers found in SrTiO 3 indicates the presence of the nearest-neighbor strontium vacancy. The next-nearest-neighbor exchange-coupled pairs of Cr 3+ in SrTiO 3 has been analyzed from the angular variation of the total electron spin of S =2 resonance lines.

Amorphous SiCxNy films (of 2.2–2.7 μm) were deposited on Si(111) substrates by reactive DC magnetron sputtering. The SiC target with small excess of carbon was sputtered at various N2/Ar gas flow ratios (0–0.48). The as-deposited films were additionally annealed at temperatures of 700, 900 and 1100 °C in the air during 30 min and at 900 °C in vacuum during 1 h. The depth profile of hardness and elastic modulus (nanoindentation), change of the film thickness, film composition and structure (Raman and Infrared spectroscopy) were investigated in dependence on annealing temperature and content of nitrogen. The hardness of the as-deposited films decreases with the growth of N2/Ar flow ratio. Air annealing at 700 °C leads to atomic short-range ordering in the amorphous SiCxNy films that significantly increases their hardness and elastic modulus at all used loads (10–100 mN). The hardness of the SiCxNy films annealed in air at 900 °C reduces when measured at low indenter loads (10–20 mN) due to onset of top layer oxidation. Hardness of inner layers, measured at 50–100 mN loads, increases approaching values exhibited by the vacuum annealed films. Air annealing at 1100 °C leads to intensive surface oxidation and formation of graphite-like structure in carbon clusters of inner layers. The hardness and oxidation resistance of the investigated SiCxNy films reduce with the increase of N2/Ar ratio.

Cubic perovskite SrTi1−xMnxO3 nanopowders with x = 0–0.5, which is much higher than the conventionally believed Mn incorporation limit, and particles sizes 10–80 nm have been successfully synthesized using the citrate sol–gel method. The crystalline structure, the morphology, the chemical composition and the lattice constant behavior versus the annealing temperature and the Mn concentration have been characterized using X-ray diffraction, scanning electron microscopy and proton-induced X-ray emission techniques. Studies of Raman light scattering and the magnetic properties revealed the activation of the TO2 polar mode and the magnetic ordering effects at low temperatures. Such features are treated as possible evidence of non-d0 Mn-driven transition to a polar phase with multiferroicity in heavily concentrated perovskite SrTi1−xMnxO3 nanopowders.

Diffusion of particles adsorbed on a heterogeneous one-dimensional chain is investigated using the theoretical approach and Kinetic Monte Carlo simulations. The concentration dependencies of the center-of-mass and Fickian diffusion coefficients are calculated for some representative values of the lateral interaction between the adsorbed particles. We thoroughly compared the analytical dependencies with the numerical data. The perfect coincidence of the data obtained by the two different methods clearly demonstrates that the analytical expressions obtained for the diffusion coefficients exactly describe the particle migration in the heterogeneous lattice gas systems.

We report on the fabrication of an amorphous Si (a-Si) thin layer by means of bombardment of a Si(100) surface using monoenergetic C 60 cluster ions with energies from 50 keV to 400 keV. The C 60 cluster implantation produces nanogranules on the surface of a-Si layer detected by atomic force microscopy. The structural disorder and thickness of the modified layer were identified using Raman spectrometry, ion channelling, spectroscopic ellipsometry (SE) and transmission electron microscopy (TEM). According to SE and TEM data the thickness of a-Si layer gradually increases with cluster ion energy reaching to about 30 nm in the 200 keV C 60 -bombarded Si sample. There is also thin layer of nanocrystalline Si found between the a-Si layer and pristine Si crystal. The obtained results represent an attractive method for creation of the a-Si layer as a functional material for opto- and nano-electronics. The study describes nanostructure created by cluster ion implantation as well as demonstrates the structural consequences of fast cluster energy dissipation in solids such as local heating and shock waves.

TiO2 films were deposited by reactive direct current magnetron sputtering on conductive and semiconductive Si as well as on dielectric quartz substrates at different negative substrate biases generated by radio-frequency (RF) power applied to the substrate holder. The mechanical properties of the films (depth sensing indentation) were examined in dependence on the film structure (X-ray diffraction and Raman spectroscopy). Hard rutile phase grows at negative substrate bias higher than 90 V, while softer anatase phase at ground or low bias (≤ 50 V) irrespective of substrate electrical conductivity. Phase composition (rutile, anatase or their mixture) as well as corresponding hardness and elastic modulus values strongly depend on electrical conductivity of the substrate at medium biases (~ 50–75 V). Phase analysis and hardness data imply that RF induced self-bias on the upper surface of quartz substrate is smaller in comparison to that on the surface of the semiconductive and especially conductive Si substrate. The rutile phase still grows after the RF power is switched off. The rutile grain size increases while hardness decreases in this case. Micro-Raman spectroscopy of residual indents in the films with anatase structure points out on the more dense high pressure TiO2-II structure formed during the indentation.

Chromium centers and their charge compensation in two single strontium titanate crystals, i.e., SrTiO3: Cr (0.05 at %) and Sr0.9995TiO3: Cr0.0005 grown with strontium deficiency, have been studied by the electron paramagnetic resonance method. The crystals have been investigated both immediately after growth and after oxidation and reduction procedures. Oxidation and reduction are performed by crystal annealing in a corresponding gas atmosphere at high temperature. Chromium centers associated with oxygen vacancy (Cr3+-VO) are detected in the reduced crystals. It is shown that strontium vacancies are formed in the crystal grown with strontium deficiency, which leads to a lowering of the tetragonal symmetry of (Cr3+-VO) and Cr5+ centers to the orthorhombic symmetry. Possible compensation mechanisms for charges of various chromium centers are considered.

The results of ion channeling studies of lattice distortions in SrTiO3: Cr single crystals are presented. Two types of single crystals containing the same amount of Cr impurities but differing in stoichiometry have been investigated. The single crystals grown by the Verneuil method have the compositions of standard-grown SrTiO3: Cr (0.05 at % Cr), whereas the single crystals grown with a strontium deficiency and a chromium compensating amount have the composition Sr0.9995TiO3 (0.05 at % Cr). Analysis of the angular channeling spectra indicates that, in crystals of both types, the main defects are Cr impurities located in octahedral sites. In the SrTiO3: Cr crystals, impurity atoms manifest themselves as Cr4+ with tetragonal Jahn-Teller distortions of the surrounding lattice. In the Sr0.9995TiO3: Cr crystals grown with a Sr deficiency, the characteristic displacements of Ti ions in the third coordination sphere of the Jahn-Teller center Cr4+ exhibit the effect of interaction of the center with a neighboring vacancy in the Sr sublattice.

The formation mechanisms of paramagnetic centers originating from Zr3+ and Cr3+ ions and the influence of the nanoparticle composition on thermal generation processes of these paramagnetic centers in ZrO2 structure were studied by electron paramagnetic resonance. A set of nanosized zirconium oxide powders (nominally pure ZrO2, ZrO2 doped with correspondingly Y2O3 and Sc2O3, Cr2O3 and Y2O3, as well as Cr2O3) was investigated: The influence of annealing on the EPR lines of Zr3+ and Cr5+ ions was found to be different. Annealing curves of EPR signals caused by Cr5+ ions have a maximum in temperature range 500–600 °C. Mechanisms of Zr3+ and Cr5+ ions formation were discussed.

Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR) spectra were studied in solvothermal- and citrate sol–gel-grown (CSGG) SrTiO3:Cr(0.1%) crystalline nanopowders. Various growth conditions and thermal treatments were used to determine defects and to tailor nanoparticles structure and crystallization processes. Solvothermal-grown nanopowders with 5 nm particle size revealed the dominant presence of the single perovskite-type phase. Annealing of the CSGG nanoparticles in air up to 800 °C leads to an increase of the particles size and the amount of the titanium dioxide (rutile and/or anatase) phase, which is initially present in small amounts in CSGG powders. It was found that paramagnetic Cr3+, Cr5+, , O−, O2− ions are present in solvothermal-grown nanopowders and in all CSGG powders. In the annealed particles the majority of paramagnetic centers (PC) are located in the particle surface and in the TiO2 phase. The nature of the PC in nanopowders exhibiting different degrees of catalytic activity in nanopowders was studied too. A correlation between O− and O2− content, synthesis conditions and particle size was found. The NMR spectra of 47Ti (I = 5/2) and 49Ti (I = 7/2) reveal a pronounced dependence of the spectral line intensity on synthesis conditions, evidencing coexistence of Ti3+ and Ti4+ ions in SrTiO3:Cr nanoparticles.

We use the inversion recovery technique with electron-spin-echo detection in order to study the non-resonant cross-relaxation of Ni2+–VLi with a faster relaxers—the exchange-coupled clusters of Ni2+ ions. An analysis of the results revealed a very high relaxation rate in non-Kramers doublet of LiF:Ni2+. The effect of a magnetic field on the spin–lattice relaxation of Ni2+ has estimated by comparing the results obtained for non-Kramers doublet around zero-magnetic field and for resonance at ~394 mT (X-band microwave frequency).

Spin reorientation phase transitions (RPTs) in magnetostatically coupled low-anisotropy ultrathin multilayers (MLs) have been studied. The RPT conditions were established and applied in a simple analytical model to describe spin reorientation between in-plane and out-of-plane magnetic phases. The proposed model has been found to be in good agreement with micromagnetic simulations. It was also shown how the magnetization orientation of MLs could be manipulated by choosing their geometrical and magnetic parameters.

A set of KTaO 3 nanopowders has been prepared at T = 180 °C using various aliphatic alcohols and water as solvents. Pronounced connection between the solvent type and potassium tantalate structures was found. Structural X-ray, TEM and Raman scattering experiments have shown that the solvent dielectric constant ɛ is an important critical parameter. At ɛ ∼ 24 the cubic perovskite-type phase was formed. Mixed perovskite and pyrochlore phases were formed at larger values of ɛ . Only pure pyrochlore phase is realized when ɛ ∼ 80. Pyrochlore-free perovskite-structure nanopowder phase formation with the particle size of ∼18 and 28 nm was achieved when ethanol and isopropanol solvents were used. Under annealing the coherent domain size decreased down to 6 and 18 nm respectively, since the amorphous phase crystallized. Crystallinity of both as-prepared and annealed powder is the best when isopropanol solvent is used.

A high-frequency (49 and 70 GHz) electron paramagnetic resonance (EPR) study is reported on SrTiO 3 single crystals doped with 0.5-at% of manganese. EPR spectra originating from the S =2 ground state of Mn 3+ ions are shown to belong to the different types of Jahn–Teller centers that arise as a result of varied ordering of the oxygen vacancies due to the reducing process. The present results indicate the strong covalent reduction of the density of unpaired spins (Fermi term) at the manganese nucleus for the various types of centers.

The photoinduced self-cleaning and super-hydrophilic properties of titania (TiO2) coated glasses are considered to be utilized in many applications. The photocatalytic activity of titania is inherent to the glass composition and to the deposition method. Particularly sodium ions diffused to the titania film from the substrate have tremendous impact on its crystallinity. The deposition method influences surface, structure, and the density of the film. This study aims to provide new findings regarding the mechanism of crystallization of sol–gel synthesized titania and its thin films deposited by means of two different methods (dip-coating and spin-coating) onto the glass substrate with a high content of sodium ions (soda-lime glass) and without sodium ions (quartz glass). The main attention is devoted to Raman spectroscopy and Raman point-to-point mapping of the films. The content and the chemical state of the sodium ions were judged using the XPS. It is shown that the dip-coating method led to dense compact material. In this case the crystallization is localized in randomly distributed centers of nucleation. Contrary the spin-coated samples embodied a web-like pattern of cracks, from which the crystallization proceeds throughout the film. Additionally SEM, AFM, XRD, GDS, UV–VIS methods were performed to support the results.

The diffusion of guest molecules in zeolites is investigated in the framework of a onedimensionallattice-gas model with two non-equivalent sites. The concentration dependenciesof the tracer and center-of-mass diffusion coefficients are calculated for some representative valuesof the lateral interaction between the guest molecules. Using simple ideas about moleculesdiffusion we propose analytical expressions for the diffusion coefficients. We compare the theoreticaldependencies with the numerical data obtained by the kinetic Monte Carlo simulations.A very good coincidence of the data obtained by the two quite independent different methodscorroborates strongly the validity of the proposed approach.

The diffusion of particles adsorbed on an anisotropic heterogeneous surface with two non-equivalent sites arranged in the alternated rows is investigated in the framework of the lattice-gas model. Analysis of the particle migration reveals rather interesting non-trivial peculiarities of this process. The particle diffusion has a qualitatively different character depending on the direction of migration and particle concentration. Using an approach describing the migration by sequences of strongly correlated particle jumps we derived the analytical expressions for the diffusion coefficients. The calculated coverage dependencies of the jump and chemical diffusion coefficients have been compared with the numerical data obtained by kinetic Monte Carlo simulations. Very good coincidence between the data obtained by two independent methods corroborates strongly the correctness of the approach for description of the particle diffusion in such heterogeneous lattices.

Strongly anisotropic photoinduced electron paramagnetic resonance spectrum was found in the KTa1-x Nb x O3 crystals with x = 0.012 at T < 10 K, which is described well within the model of the center with S = 1, g ∥ = 0.82 ± 0.04, g ⊥ = 0.52 ± 0.04, and D = 0.44 ± 0.03 cm−1. Analysis shows that this spectrum originates from the Nb4+−O− polaronic exciton in the triplet state.

A High Power Impulse Magnetron Sputtering System (HiPIMS) equipped with a titanium target 5 cm in diameter has been investigated by means of a time-resolved Langmuir probe and time-resolved ion flux probe. The plasma parameters have been measured in a distance of 70 mm from the target face and below the racetrack. The ion flux at the substrate (placed at the same position as the Langmuir probe) has been determined from the voltage drop across a resistor connected with the planar probe. The planar probe was pulsed at a repetition rate of 50 kHz, duty cycle 50%. The effects of working gas pressure and mean discharge current have been investigated. Fine temporal resolution of the measured probe characteristics revealed a decrease in the effective electron temperature T eff during pulse-ON time followed by a steady value at 0.6 eV for all the pressures during the rest of the period. For the pressure of 2 Pa, we observed a local maximum in T eff (0.9 eV) at the end of cathode voltage pulse. Furthermore, during the pulse-OFF time we observed an exponential-like decay of the electron temperature for all the pressures. The plasma density demonstrated a steep increase during pulse-ON time followed by an exponential-like decrease during plasma OFF phase. The ion flux measurements have revealed approximately 3 times higher magnitude in the ion flux on the substrate at low pressure than at higher-pressures. The influence of these phenomena on the total energy flux at substrate and on thin film properties is discussed.

In this work, Pb(Zr,Ti)O 3 (PZT) thin films were deposited onto flexible Cu-coated Kapton® substrates by means of reactive magnetron sputtering for the first time. Different power supplies were selected for each of the 200 mm targets to adjust film composition and substrate ion bombardment. High-power pulse sputtering has been employed for the Zr-target to enhance for formation of nanocrystals, pulsed DC sputtering for the Ti-target to provide a high enough sputter yield, and RF-sputtering for the Pb-target to prevent droplet formation. The deposited films had a lead-enriched layer at the surface and their film composition was in rhombohedral range near the morphotropic phase boundary of the PZT phase diagram. XRD revealed a nanocrystallite mixture of lead, zirconium and titanium oxides in the as-deposited films which can be transferred into perovskite Pb(Zr,Ti)O 3 by rapid temperature annealing. Observed piezoelectric properties demonstrate that rapid-temperature-annealed films are promising for application in flexible piezoelectric sensors, actuators and power generators.

Study of optical and electrical properties of Mn doped ZnO films deposited by atmospheric barrier torch discharge technique on SiO2 substrates is reported for a wide range of Mn concentration (0.2–20 at.%). It was found that the growth of all Mn-doped ZnO films contains secondary Mn2O3 phase even for the lowest manganese concentration (0.2%). When Mn concentration is in the range 0.2–4%, this secondary Mn2O3 phase does not conspicuously affect Raman spectra of ZnO evidencing that Mn is mostly incorporated into the ZnO host matrix. Increase of Mn concentration (8–20%) is accompanied by formation of Mn2O3 clusters manifesting itself in the appearance of a corresponding mode in the Raman spectra. These clusters influence dramatically optical and electrical properties of the films. The Mn “solubility limit” for the films growth technique used is determined to be near 8%.

We report the results of a multifaceted study of optical and dielectric properties of erbium-doped (500 ppm) potassium tantalate incipient ferroelectric single crystals. Studies of optical absorption and photoluminescence spectra allowed us to determine the system of energy levels that control the main internal optical transitions in the 4f electronic shell of Er3+ in KTaO3. It was found that at least two types of Er3+ centres, major and minor ones, are present. The major centres are non-cubic, formed by Er3+ substituting for K+ sites; these are responsible for the n-type conductivity of KTaO3:Er crystals. Wideband optical absorption with a maximum at 1.13 eV (λ = 1097 nm) was observed in the near-IR range and was attributed to polaron formation. Low-temperature far-infrared reflectivity studies revealed an increase in the frequency of the lowest transverse optical mode and a decrease in the dielectric permittivity in comparison with undoped KTaO3 crystals. This stiffening means the suppression of the ferroelectric instability in the system.

Amorphous B4C films were prepared by magnetron sputtering of the hot-pressed B4C target in different regimes. Hardness, intrinsic stress and film structure were investigated in dependence on the annealing temperature in air. Changes in the film structure and composition were investigated by Raman spectroscopy, confocal microscopy, and electron probe microanalysis. It has been shown that an annealing at 500 °C for 1 h leads to stress reduction, slight thickness decrease and increase of film hardness. However already at 600 °C the film oxidation proceeds very intensively with formation of the phases of boron oxide and amorphous carbon in the surface layer. The thickness of the film decreases quickly. The film oxidation is accompanied by formation of numerous carbon hillocks and redistribution of film material after annealing in furnace at 500 and especially 600 °C. The oxidation of a-B4C films as well as of the crystalline bulk samples starts in some locations and has clearly pronounced heterogeneous character that indicates heterogeneous structure of amorphous films as well as of bulk crystalline samples. Annealing in air for a long period shifts down the onset of formation of hillocks to 400 °C and changes in film morphology to 300 °C. Thus the upper temperature limit for application of a-B4C films in air depends also on the exposure time at the operation temperature.

We have considered the diffusion of particles in a dynamically disordered medium in the framework of a simple lattice-gas model of a reconstructive surface. Using kinetic Monte Carlo simulations we have investigated the diffusion of particles over the host lattice with moving atoms. The dynamic lattice reconstruction increases substantially the particle diffusion coefficient and changes its activation energy.

The basic objective of this work is related to the research on the design of hierarchic multilayer systems with the assumed final functionality utilized for microelectronics and photovoltaics. We report on photoelectrochemical functionality of the multilayer system consisting of carbon nanofibers (CNFs)/photoactive anatase TiO 2 /conductive ZnO thin films. The CNFs’ layers were obtained by annealing the polyacrylonitrile (PAN) web deposited by the electrospinning method. Titanium dioxide and zinc oxide layers were deposited by means of a hollow cathode cold plasma deposition system. Raman spectra confirmed carbon nanofibers, crystalline TiO 2 and ZnO forming individual layers as well as the final multilayer assembly. A mixture of various Zn x Ti y O z phases was also observed. These structures were produced due to the reactions between the highly energetic zinc ions generated in the plasma environment and the TiO 2 layer. The same phenomenon is probably responsible for the doping of TiO 2 by carbon atoms originating from CNFs and leading to a significant decrease of the photocatalytic activity.

Optical properties of PbZr x Ti 1 − x O 3 material have been actively studied in the visible and near band-gap region, but data in the vacuum-ultraviolet spectral region is rather scarce. In this work we focus on well known interband transitions for the perovskite materials, 2 p → dγ , located in VUV spectral region. Dielectric functions of chemical solution deposited and sputtered PZT were obtained in the spectral range 1–8.8 eV. Differences between the absorption maxima for chemical solution deposited and sputtered PbZr x Ti 1 − x O 3 samples near Kahn–Leyendecker 2 p → dγ interband transition were found and are interpreted by change of interatomic distances. This is confirmed by different lattice constants. In the case of PbZr x Ti 1 − x O 3 film with microcracks, the void fraction was estimated from the effective medium approximation. Direct band-gap energies appear to be nearly the same for all reactive sputtered samples weakly depending of Zr/Ti concentration.

Amorphous hydrogen-free silicon carbide (a-SiC) coatings demonstrate good adhesion to different steel substrates, low intrinsic stress and high hardness however show quite high coefficient of friction in comparison with carbon-based coatings. Some addition of carbon to SiC can promote the decrease of friction coefficient. In the present work the amorphous hydrogenated silicon-carbide (a-SiC:H) films with different C/Si ratio were prepared at room temperature using DC magnetron sputtering in two ways: (i) sputtering of silicon target; (ii) sputtering of SiC target, both in the gas mixture of Ar and CH 4 . In the latter case the films contained less hydrogen at the same C/Si ratio. The mechanical and tribological properties of these films were studied to find their optimum combination. The hardness, elastic modulus (nanoindentation), intrinsic stress (Stoney's formula) and coefficient of friction (pin on disc tribometer) were examined in dependence on the technological parameters, film structure and composition (Raman spectra, electron probe microanalysis). An increase of carbon in the films from 50 to 70 at.% resulted in decrease of hardness and friction coefficient. In the first case (i) the hardness decreased from 13 to10 GPa and in the second case (ii) from 23 to 16 GPa. Thus sputtering of SiC target in the gas mixture of Ar and CH 4 allows obtaining at room temperature the films with C/Si > 1 in which relatively high hardness (16–18 GPa) and low friction coefficient (~ 0.15) are combined.

Size-controlled Cu clusters are formed in a system which combines pulsed magnetron sputtering and gas condensation at room temperature. The discharge repetition frequency (0.1–25 kHz) and the duty cycles (20–90%) of the magnetron sputtering are varied systematically, the influence of discharge current (100–800 mA) and the pressure in the condensation tube (25–90 Pa) is also investigated. The cluster mass is determined by a quadrupole mass filter in the aggregation tube, and the cluster size by atomic force microscopy (AFM) imaging of deposited clusters. For all preparation conditions, the cluster mass shows a log-normal distribution. A non-monotonic frequency dependence with a maximum at 1 kHz and 20% of duty cycle is observed (about 10 5 amu, or cluster diameter 8–10 nm). By adjusting discharge frequency and duty cycle, the cluster mass can be decreased by one order of magnitude. We suggest that this effect is caused by energy dissipated into the aggregation tube; and find a critical buffer gas temperature T g-cr which limits cluster growth. This view is supported by the constant cluster mass flux which does not change on variation of discharge repetition frequency or duty cycle. This feature indicates mass conservation.