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Amorphous metal-oxide semiconductors can be readily prepared by a solution process at low temperatures, and their energy band structures and carrier concentrations can be controlled based on the oxide composition or the addition of dopants in the design of thermoelectric (TE) materials. However, research on the correlation between the charge transport and TE performance of amorphous metal-oxide semiconductors is still in its infancy. Herein, we present the energy-dependent TE performance characteristics of Li-doped ZnO thin films with different doping levels and charge carrier concentrations. Thin films were prepared by the solution process, and the Li doping level was controlled by the Li precursor concentration added to a Zn precursor solution. Subsequently, a field-effect-modulated Seebeck coefficient measurement device was built to study the energy-dependent TE performance. Notably, the higher ratio of interstitial Li (Li

Purpose. As40 − x Sb x S60 amorphous films are suitable for creation of highly efficient, diffraction gratings, optical diffraction elements, optical compact-disks and sensors, waveguides, elements for infrared and nonlinear optics. This paper is devoted to investigation of Raman spectra of glasses and films and transmission spectra of films in As-Sb-S system with the Sb content up to 12 at % and their changes under laser radiation. Methods. Raman and optical spectroscopy, atomic forse microscopy. The transmission spectra were studied in 400-750 nm range at room temperature using a diffraction monochromator “MDR-23”. The spectral resolution was no worse than 10-3 eV. Results and discussion: Increased concentration of antimony in the composition of As40 − x Sb x S60 (0 ≤ x ≤ 12) amorphous films and laser irradiation ( λ =530 nm) of them result in the shift of their absorption edge to the longwave range. In this case the pseudogap width E g decreases, whereas the index n increases. Under the same conditions of irradiation, the largest changes in optical parameters occur in the As36Sb4S60 film. Changes in the optical characteristics of films are caused by photostructural transformations taking place in them under the laser irradiation. The nanoheterogenous structure of the studied films was established. The structural matrix of As40 − x Sb x S60 films is built from As(Sb)S3 pyramidal units connected by bridging S atoms. No molecular fragments with Sb-Sb bonds in the structure of films were detected. However, the large amount of structural groups with homopolar As-As (As4S4, As4S3) and S-S bonds (Sn) are present in the structure of films. The laser irradiation of As40 − x Sb x S60 films leads to the breaking and switching of As-As and S-S bonds in As4S4, As4S3, and Sn type structural fragments. Accompanied with the formation of structural units with heteropolar bonds As-S (AsS3). These structural transformations are related with the decreasing content of molecular fragments possessing homopolar bonds in films matrix. Conclusions. Transmission and Raman spectra of as-prepared and irradiated As40 − x Sb x S60 amorphous films were investigated. The nanoheterogenous structure of the studied films was confirmed by Raman spectra. It was established that the growth of the Sb content in composition of films and irradiation induced the absorption edge shift to the longwave region, E g decreased and n increased. The largest changed in optical parameters of as-prepared and irradiated films occur in the As36Sb4S60 film. These changes are caused by the photostructural transformations, which are accompanied by decreasing in the number of structural groups with homopolar bonds in films matrix.

Li–Nb–O amorphous films were deposited onto Si substrates by the radio-frequency magnetron sputtering method in an Ar environment. As-grown films are crystallized under thermal annealing (TA) at the temperature of up to 600 °C with a formation of LiNbO3. Capacitance–voltage and current–voltage analysis revealed a positive fixed oxide charge existed in the films. TA influences the structure and electrical properties of as-grown films. The fraction of a crystalline phase in the film increases from 45 to 100% when raising the annealing temperature from 450 to 475 °C. The effective positive charge in the amorphous films changes non-monotonically with TA reaching a minimum value at the temperature of 450 °C when the effective dielectric constant has a maximum value. The concentration of traps in the films depends on the annealing temperature and reaches a minimum value at T = 600 °C which is caused by the formation of the large-block crystalline structure. Charge transport mechanisms are also discussed.

Kinetics of autoepitaxial crystal growth in amorphous films of Cr2O3 were studied by the methods of transmission electron microscopy “in situ” with video registration of structural changes. With frame-by-frame analysis of the video, the kinetic curves of the time dependence of the radius, length and width of growing crystals with different morphological types (needle-shaped and disc-shaped crystals) were obtained. The time dependence of fraction of the crystallized material was determined. Crystallization front may be splitting into slices that can move at different speed. The conclusion was made that the autoepitaxial crystal growth is the type of layer polymorphous crystallization of amorphous films.

The architecture consisting of films resting on a ductile substrate is ubiquitous in a wide variety of applications. A typical failure mechanism of such a structure is cracking of the films. In this study, the calculations for the notch tip fields in a metallic glass film deposited on a ductile substrate are carried out to explore the fracture mechanisms of the amorphous films. The amorphous film is characterized by an isotropic elastic-plastic model which captures the pressure sensitive yielding and post-yield strain softening behavior of metallic glasses, and the substrate is taken to be an elastic-plastic solid with the flow rule given by von-Mises flow theory. It is found that the thick amorphous films exhibit high opening stress and small plastic deformation , indicating that brittle cracking of the films tends to be the dominant fracture mode. Whereas, the low opening stress is observed and shear bands develop in the case of thin amorphous films, implying that the cracking caused by shear bands governs the fracture of films. We further revealed that the pressure sensitive yielding plays an important role in the fracture of amorphous films; large degree of pressure sensitivity enables low opening stress and enhanced plastic deformation in the films, increasing the propensity of formation of shear bands. The findings of this study provide plausible explanations for the experimentally observed fracture behavior of amorphous films on ductile substrates, and shed new light on the fracture mechanisms of such a structure.

The fragmentation and interfacial stress transfer of Cu75Zr25 amorphous films with varying film thickness (h) on polyimide substrates were systematically investigated by using uniaxial tensile testing, in combination with in situ optical microscope and atomic force microscope characterizations. It is revealed that the interfacial stress transfer length increases monotonically as h increases. The interfacial stress transfer mechanism changes from elastic-plastic to approximately linear elastic at a critical point of h = 250 nm. This is related to h-dependent deformation-induced devitrification (DID) near the interfaces that the thinner Cu-Zr amorphous films display more DID. This study elucidates for the first time the effect of DID on the interfacial stress transfer, which will be helpful to design the interface with desired property for nanotechnological applications.

The phenomenon of spontaneous spin reorientation in Gd–Сo amorphous films, which results from the competition between the perpendicular magnetic anisotropy and shape anisotropy, is studied. It is shown that the reorientation occurs via the formation of a fine-grained nonuniform magnetic structure called hypercritical state in a wide temperature range. Magnetic domains in the spin-reorientation region are characterized using magnetic and magneto-optical measurements. Based on the experimental magnetometric data and results of simulating the temperature dependences of spontaneous magnetization, the phase diagram of the films containing 16–26 at % Gd is constructed, which, being plotted on coordinates elemental composition—temperature, exhibits the ranges of existence of the perpendicular anisotropy, transition magnetic anisotropy (hypercritical state), and planar magnetization state.

The buckling and post-buckling behavior of the Cu–Zr amorphous films is highly dependent on film thickness (h) and applied strain (e). A buckling map has been developed with h and e as axes, where four buckling modes are detected, including uncracked triangular buckle, cracked rectangular buckle, cracked triangular buckle, and patches. Formation of the four buckling modes will be discussed in terms of the film thickness and size-dependent deformation.

Without applying an in situ magnetic field, soft magnetic Co40Fe40B20 films were successfully deposited onto rotating silicon substrates using the oblique sputtering technique. Different thicknesses could be achieved by controlling the sputtering time. The corresponding static and dynamic electromagnetic properties were then systematically investigated. Interestingly, as the thickness increased from approximately 50 nm to 250 nm, the imaginary part of the permeability spectra of CoFeB films changed from a single peak to double peaks and then to a broad single peak. Ferromagnetic resonance (FMR), crystalline structure and cross-section SEM analyses evidenced that the double peaks of the permeability spectra are attributed to double anisotropies and anisotropic diffusion. The overlapping double FMR peaks provide a wide absorption frequency band over 2 GHz, which is critical for the design of an electromagnetic interference suppressor.

The morphology and kinetics of crystals growth in amorphous films of Cr2O3, ZrO2, and HfO2 have been studied by the methods of transmission electron microscopy (“in situ”) with video registration of structural changes. Based on the frame-by-frame analysis of the video the kinetic curves of the phase transformations have been constructed, which reveal typical features of the main crystallization modes: layer (Cr2O3), island (ZrO2), and dendrite (HfO2) polymorphous crystallization. For each mode the numerical values of the relative crystallization lengths (2036 for Cr2O3, 77 for ZrO2 and 4180 for HfO2) are determined. The crystal growth modes at electron-beam heating of amorphous films are compared with crystal growth modes on substrates at vapor condensation in vacuum (Frank-van der Merwe, Volmer-Weber and Stranski-Krastanov growth modes).

Bulk glassy Se98Te2 and Se96Te2X2 (X = Zn and Cd) were prepared by melting quenching method. Thin films of various thicknesses (200 – 670 nm) were obtained by the thermal evaporation method. The structure of the prepared compositions was investigated by X-ray and EDX analysis. We studied the effect of Zn and Cd addition on the electric and dielectric properties of Se98Te2 thin films. Our measurements were studied in the temperature range (298-323K) below the glass transition temperature and frequency range (100 Hz-1 MHz). DC conductivity showed a single conduction mechanism by hopping of charge carriers at the band edges for the studied system. The dependence of Ac conductivity on frequency is linear with frequency exponent s lies very close to unit and is independent of temperature. This can be explained by the correlated barrier hopping (CBH) model. The dielectric constant ε1 and dielectric loss ε2 noticed to decrease with frequency and increase with temperature. The maximum barrier height Wm was calculated according to Guinitin.

Side-chain substitutions have important influence on the aggregation of perylene diimide (PDI), which show a great impact on their excited-state dynamics as well. Herein, by employing photoluminescence (PL), time-resolved photoluminescence (TRPL) and transient absorption (TA) spectroscopy, we investigated excited-state dynamics of two perylene diimide (PDI) derivative amorphous films, i.e. undecane-substituted PDI (PDI-1) and diisopropylphenyl-substituted PDI (PDI-2), fabricated with spin coating method. Femtosecond transient absorption spectra reveal that both films show pronounced ground state bleach (GSB) with lifetime longer than 10 ns while the relaxation of excited state absorption (ESA) has typical lifetime less than 1 ns. The significant feature of excited state decay in PDI-2 is dominated by transforming the singlet excited state into two triplet states via singlet fission, which is evidenced by the appearance of triplet state absorption. By contrast, the absence of triplet state absorption and the appearance of long-lived emission species in PDI-1 suggest that the decay of excited-like state could be dominated by the formation of excimer. Our present study reveals for the first time that the singlet fission does occur in amorphous PDI film, the study also demonstrates that side-chain substitutions have great impact on the excited-state dynamics of PDI.

Stray fields of magnetic systems with a known degree of structural and magnetic nonuniformities have been mapped using indicator amorphous films with a perpendicular anisotropy. The characteristic magnetooptical patterns have been determined, which correspond to the distribution of the magnetic-field component normal to the plane of the indicator films. The theoretical patterns of model magnetic systems that are similar to the studied systems in the degree of the structural and magnetic nonuniformity have been calculated. The validity of the magnetooptical visualization has been confirmed by comparison of the experimental and theoretical patterns. The possibility of the express monitoring of the parameters of the magnetic system has been shown using a laboratory model of a magnetooptical visualizer by the observation of the magnetooptical contrast of gadolinium–cobalt indicator films under the action of an ac magnetic field.

We present measurements of significant thermal diffusivity by surface electromagnetic waves of an ultra-thin polar and amorphous dielectric film deposited on silicon (Si). We used a photothermal-beam-deflection technique with a modulated mid-infrared heating source to excite and launch surface electromagnetic waves onto the surface of an amorphous silicon carbide (a-SiC) film deposited on Si and generate periodic temperature and refractive index gradients above the sample surface. These gradients are capable of periodically deflecting a probe beam, passing very close to the surface, at the modulation frequency of the heating beam. We have fitted the measured probe beam deflection to an analytical model for the mirage effect that takes into account the thermal anisotropy of the measured sample to infer the contribution of the surface electromagnetic waves of the a-SiC film to thermal diffusivity in the plane of the sample under study. We found that reducing the thickness of the a-SiC film promotes the interaction between the surface electromagnetic waves propagating on either side of the a-SiC film, which significantly enhances thermal diffusivity in the plane of the measured sample. We also found that in-plane thermal diffusivity by surface electromagnetic waves on an amorphous silicon carbide film a few nanometers thick is several orders of magnitude greater than thermal diffusivity by phonons in silicon. We believe that the results obtained provide a better understanding of the physics of electromagnetic waves confined to solid surfaces.

An electron microscopic investigation was performed on the structure and kinetics of the crystallization of amorphous Cr2O3 films, deposited by pulsed laser sputtering of chromium target in an oxygen atmosphere. The crystallization was initiated by the action of an electron beam on an amorphous film in the column of a transmission electron microscope. The kinetic curves were plotted on the basis of a frame-by-frame analysis of the video recorded during the crystallization of the film. It was found that the amorphous phase – crystal phase transition in Cr2O3 films occurs as a layer polymorphic crystallization and is characterized by the values of the dimensionless relative length unit δ0 ≈ 2000–3100. The action of the electron beam initiates the formation of crystals of two basic morphological forms: disk-shaped and sickle-shaped. Growth of a disk-shaped crystals is characterized by a constant rate v and the quadratic dependence of the fraction of the crystalline phase x on the time t. Sickle-shaped crystal at an initial stage, as it grows, becomes as ring-shaped and disk-shaped crystal. The growth of a sickle-shaped crystal is characterized by normal and tangential velocity components, which depend on the time as ∼√t and as ∼1/√t respectively The end point of the arc at the interface between the amorphous and crystalline phases as the crystal grows describes a curve, which is similar to the Fermat helix. For sickle-shaped, as well as for disk-shaped crystals, the degree of crystallinity x ∼ t2.

Through electroless plating, the Al0.3CoCrFeNi high-entropy alloys were successfully coated with the Ni-P amorphous film with a thickness of 1.2 μm. For studying the surface change of samples after chemical plating, the surface morphologies of the as-cast HEA substrate and HEA with the Ni-P film were contrasted by atomic-force microscopy. The tensile properties of the samples with and without the Ni-P film, and the deformational behavior of thin Ni-P film were researched, respectively. In addition, the effect of the Ni-P amorphous film on corrosion resistance of the coated HEAs was also investigated. The experimental results show that in contrast to the uncoated samples with a yielding strength of 275 MPa, the yielding strength of the coated samples exhibits 400 MPa, with a 45% improvement, which can be attributed to the very high yield strength of the Ni-P amorphous film. A tensile strain up to 10% was achieved in the Ni-P film since the propagation of one primary shear band was inhibited, and the stress/strain concentration was retarded by the plastic substrate. The corrosion resistance of the HEA with the Ni-P film is superior to that of the bare HEA in the 3.5 wt percent NaCl solutions due to the chemical homogeneity and the absence of microscopic defects in the Ni-P amorphous film. The current results indicate that the surface coating is an effective means for optimizing the properties of HEAs, and the thin Ni-P coating can remarkably improve the strength of the present HEAs.

Structure and its transformation are examined for amorphous Se-rich AsxSe1-x (0 ≤ x ≤ 0.2) alloys by employment of diffraction and non-diffraction structural probes. It is shown that the molecular structure of amorphous Se (a-Se) on the scale of short-range order is close to that of crystalline phase, while medium-range order differs from the structure of most inorganic glasses and may be placed between three-dimensional network glasses and polymeric ones. Further experiments show the existence of successive phases in laser-induced glass-crystalline transition with pronounced threshold behavior. Below the energy density threshold, Eth, only small changes in the local structure of the system can be detected. Above Eth, the changes were attributed to crystallization transformation. The corresponding Raman spectra reveal transformation of the system from amorphous into the crystalline phase under laser irradiation. In the binary AsxSe1-x glass system, a change of structural regime takes place near the composition x ≈ 0.04. The presence of this topological threshold is established by direct and indirect evidence, such as peculiarities in the composition dependence of the basic parameters for electron diffraction and Raman vibration modes. The peculiarities are caused by the transition from a chain-ring-like structure to preferentially a chain-like structure. Experiments described in this section have shown that Raman technique is a particularly sensitive method to determine the presence of microcrystal's in the glassy matrix. Room-temperature polarized Raman scattering spectra of model glass have been collected. Low-frequency peaks were observed in the spectra. A model is proposed for explanation of their appearance. It is shown clearly that the low-frequency Raman spectra allow determining the conditions at the boundaries, sizes as well as concentration of micro-heterogeneities in non-crystalline materials. It was established earlier that for all amorphous (glassy) materials a low-frequency peak, observed in the corresponding spectral region of Raman scattering and called boson peak, is inherent. This peak is absent in crystals of the same chemical composition and is associated with space correlations on the scale of medium-range order Rc ≈ 10 A. On the contrary, less known is that a boson peak can give important information about the presence of microcrystalline inclusions and heterogeneities in the low-frequency Raman spectra of glasses irrespective to their chemical composition.

Thin films of In-doped Ge-S in the form of Ge35In8S57 with different film thickness were deposited using an evaporation method. The X-ray diffraction studies demonstrate that the as-prepared films are amorphous in nature for these films. Some optical constants were calculated at a thickness of 150, 300, 450 and 900 nm and annealing temperature of 373, 413, 437 and 513 K. Our optical observations show that the mechanism of the optical transition obeys the indirect transition. It was found that the energy gap, Eg, decreases from 2.44 to 2.20 eV with expanding the thickness of the film from 150 to 900 nm. On the other hand, it was found that Eg increases with annealing temperature from 373 to 513 K. The increment in the band gap can be attributed to the gradual annealing out of the unsaturated bonds delivering a decreasing the density of localized states in the band structure. Using the single oscillator model, the dispersion of the refractive index is described. The dispersion constants of these films were calculated with different both thickness and annealing temperatures. Additionally, both of nonlinear susceptibility, χ(3) and nonlinear refractive index, n2 were calculated.

Amorphous FeVSb-based thin films doped with Ti are deposited by magnetron sputtering. The microstructure, thermal stability, and thermoelectric properties of the films are systematically investigated. The as-deposited (FeVSb)1−xTix films possess an amorphous structure that is thermally stable up to 473 K. The non-doped FeVSb film is an n-type semiconductor. When Ti is doped into the FeVSb film, the (FeVSb)1−xTix films with x from 0.02 to 0.10 are p-type semiconductors. The thermal conductivity values of the FeVSb and (FeVSb)0.94Ti0.06 films measured by the suspended thermal bridge method are 1.18 and 0.93 W m−1 K−1 at 300 K, respectively, which are much lower than those of half-Heusler crystalline bulk materials due to the amorphous structure of these films. The thermoelectric figure of merit ZT is calculated to be 0.09 and 0.23 at 300 K for the FeVSb and (FeVSb)0.94Ti0.06 films, respectively. A planar thermoelectric generator (TEG) with 4 thermocouples based on amorphous (FeVSb)1−xTix films is fabricated. The maximum output power and open-circuit voltage of the TEG are 248 nW and 15.4 mV at a temperature difference of 59.4 K. Our results demonstrate that the amorphous (FeVSb)1−xTix film with ultra-low thermal conductivity and high ZT at room temperature is a high-performance TE material for TEGs.

Thin homogeneous amorphous films of bulk crystalline material AgSnSbS3 were obtained by thermal evaporation in vacuum. The films demonstrate stability under irradiation by focused and scanning electron beams inside transmission electron microscope at 200 Kv. Some crystalline features appeared for the sample annealed at 390 °C are characterized.Thin homogeneous amorphous films of bulk crystalline material AgSnSbS3 were obtained by thermal evaporation in vacuum. The films demonstrate stability under irradiation by focused and scanning electron beams inside transmission electron microscope at 200 Kv. Some crystalline features appeared for the sample annealed at 390 °C are characterized.

Electron-microscope investigations in situ, concerning the crystallization of amorphous films, are systematized. Based on the analysis of the structure and morphology of crystals growing in amorphous films as a result of electron beam influence, a quantitative interpretation of layer polymorphic crystallization (LPC), island polymorphic crystallization (IPC) and dendrite polymorphic crystallization (DPC) is given. For each crystallization mode the parameter of dimensionless relative length δ0, equal to the ratio of the characteristic length to the value, characterizing the size of the unit cell of the crystal, was respectively assigned. Based on the video recording of the process, the kinetic curves of LPC, IPC and DPC are constructed. LPC (Cr₂O₃, V₂O₃, Sb₂S₃, Se and others) is regarded as morphological analog of Frank-van der Merwe (FM) growth mode of a crystal from the vapor phase. In the case of LPC in the zone of observation in amorphous film grows a single flat crystal. By analogy with FM growth mode an energy criterion of the LPC can be written as σa≥ σc + σ>ac + εd, where σa is the free energy of the amorphous phase-vacuum interface, σc is the free energy of the crystalline phase-vacuum interface, σac is the free energy of the amorphous-crystalline phase interface, and εd is the energy of deformation of the growing crystalline layer. For LPS the quadratic dependence of the fraction of the crystalline phase x on time t takes place and δ0 ~ 2500-4700. IPC (Al₂O₃, ZrO₂, Ni, Re and others) is regarded as morphological analog of Volmer-Weber growth mode of a crystal from the vapor phase. In the case of IPC in the zone of observation in amorphous film grows a lot of small disoriented crystals. By analogy with VW growth mode an energy criterion of the IPC can be written as σa ≤ σc + σac + εd. For IPS the exponential dependence of x(t) takes place and δ0 ~ 100-900. DPC (films of Fe-C, HfO₂) is regarded as morphological analog of Stranski-Krastanov growth mode of a crystal from the vapor phase. A characteristic sign of DPC is the formation of dendrite branches along the sides of a flat single crystal. For DPC the quadratic dependence of x(t) takes place and δ0 ~ 3900.

Binary and ternary Fe-W and Fe-W-P films have been obtained electrochemically by using an alkaline stable bath of Fe(III) with a new complexing agent (nitrilotriacetic acid trisodium salt monohydrate-NTA), adequate to avoid carbon incorporation in the deposits and assure the bath durability. The different stages to obtain the alloy deposits through induced co-deposition have been proposed. Significant tungsten percentages in the deposits have been obtained, resulting stable amorphous films with soft-magnetic properties. However, it has been necessary to simplify the deposition process to obtain Fe-W alloy nanowires by means of induced co-deposition in the interior of polycarbonate membranes. For first time, Fe-W magnetic nanowires have been synthesised by templated induced co-deposition.

Nanocrystalline materials often exhibit extraordinary mechanical and physical properties but their applications at elevated temperatures are impaired by the rapid grain growth. Moreover, the grain growth in nanocrystalline oxide nanofibers at high temperatures can occur at hundreds of degrees lower than that would occur in corresponding bulk nanocrystalline materials, which would eventually break the fibers. Herein, by characterizing a model system of scandia-stabilized zirconia using hot-stage in situ scanning transmission electron microscopy, we discover that the enhanced grain growth in nanofibers is initiated at the surface. Subsequently, we demonstrate that coating the fibers with nanometer-thick amorphous alumina layer can enhance their temperature stability by nearly 400 °C via suppressing the surface-initiated grain growth. Such a strategy can be effectively applied to other oxide nanofibers, such as samarium-doped ceria, yttrium-stabilized zirconia, and lanthanum molybdate. The nanocoatings also increase the flexibility of the oxide nanofibers and stabilize the high-temperature phases that have 10 times higher ionic conductivity. This study provides new insights into the surface-initiated grain growth in nanocrystalline oxide nanofibers and develops a facile yet innovative strategy to improve the high-temperature stability of nanofibers for a broad range of applications.

Soft magnetic Co40Fe40B20 films with different tilt angle were successfully deposited on silicon substrates by using oblique sputtering technique. Different oblique angles are achieved by controlling the position of samples. The corresponding static magnetic properties of these samples were then systematically investigated. Interestingly, with the oblique angle increasing from 38° to 55°, the MOKE hysteresis loop of the thin films displays a unique and special performance with double hard axes. Meanwhile, despite of the measurement magnetic field along PR or AR direction, both of the hysteresis loops have two-stage magnetization reversal that means there are two comparably strong anisotropies in the CoFeB films. Moreover, rotating samples from in-plane to out-of-plane, the hysteresis loops demonstrate the perpendicular anisotropy exist in CoFeB films. The cross-section SEM characterizations further verify that the residual field from the magnetic cylinder will strongly impact the microstructures of thin film.

Hereby, we present In-Sb-Te amorphous films grown by pulsed laser deposition technique using, as targets, crystalline ingots (with corresponding stoichiometry) prepared by traditional melt-quenching method. The explored nominal compositions were In50Sb15Te35, about a ternary compound formed in the quasi-binary InTe-SbTe system, metastable at room temperature, and two eutectics In8Sb8Te84 and In10Sb51Te39. Measurements of electrical sheet resistance evidenced that the amorphous films behave as electrical insulators at room temperature and present a giant jump in resistivity towards a conducting state on crystallization. Differential scanning calorimetry technique complemented the structural information obtained by X-ray diffraction and revealed temperatures of crystallization of the amorphous films as well as their melting points. Due to their temperature characteristics (crystallization temperature ≈ 225 °C and melting temperature ≈ 540 °C), In10Sb51Te39 film results very attractive from technological point of view. These characteristics could make this eutectic composition a good candidate for using in phase-change memory devices. Fil: Bilovol, Vitaliy. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentina Fil: Arcondo, Bibiana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentina

Organisms in nature can alter the short-range order of an amorphous precursor phase, thereby controlling the resulting crystalline structure. This phenomenon inspired an investigation of the effect of modifying the short-range order within the amorphous phase of a selected material. Amorphous thin films of aluminum oxide deposited by the atomic layer deposition method were found to vary structurally as a function of size. Thinner films, as predicted and also confirmed by atomistic simulations, exhibited more 4 coordinated alumina sites. These atomistic alterations were expected to change the amorphous thin film average density. The density indeed varied with the alumina layer thickness, and the measured effect was even stronger than predicted theoretically. This effect is explained in terms of the deposition process, where each newly deposited layer is a new surface layer that remembers its structure, resulting in thin films of substantially lower density.

We propose a simple, low-cost, and large-area method to increase the thermoelectric figure of merit (ZT) in silicon membranes by the deposition of an ultrathin aluminum layer. Transmission electron microscopy showed that short deposition of aluminum on a silicon substrate covers the surface with an ultrathin amorphous film, which, according to recent theoretical works, efficiently destroys phonon wave packets. As a result, we measured 30-40% lower thermal conductivity in silicon membranes covered with aluminum films while the electrical conductivity was not affected. Thus, we have achieved 40-45% higher ZT values in membranes covered with aluminum films. To demonstrate a practical application, we applied this method to enhance the performance of a silicon membrane-based thermoelectric device and measured 42% higher power generation.

The magnetic properties of the Dy-Co binary system thin films were studied. The compositional dependences of the residual magnetization, the coercivity in the ground state, and the magnetic ordering temperature were determined. The intervals of the compositions corresponding to the asperomagnetic and sperimagnetic structures are established. Within these structures, the dependence of the average magnetic moment per Dy atom was calculated, and the fan of the Dy magnetic moments was concluded to be narrowed monotonously with increasing Co content in the range of 20–80 at.%.

Electron-beam crystallization of amorphous films of Yb2O2S was studied by the methods of transmission electron microscopy “in situ” with video registration of structural changes. The kinetic curves, demonstrating the dependence on time of the crystals density and of the fraction of the crystalline phase was obtained with the help of frame-by-frame analysis of the video. The formation of the polycrystalline film occurs at a constant crystal growth rate and at a constant intensity of nucleation of crystallization centers, which corresponds to α-version of the Kolmogorov's model. The phase transformation in amorphous films of Yb2O2S occurs in accordance with the island polymorphous crystallization mode with the relative length δ0≈ 1030. At small layer thicknesses of Yb2O2S (d ≤ 20 nm) the effect of stabilization of the amorphous state was observed.

The architecture consisting of a thin film resting on a substrate is a common feature in a wide variety of applications. Understanding of the failure mechanisms is essential for design of reliable film/substrate systems. Recent experiments showed that shear banding induced fracture and brittle cracking of films are two major fracture modes in the structure composed of an amorphous metallic glass film bonded to a metal substrate. In this study, we carry out numerical analyses of fracture in amorphous films resting on ductile substrates, with the aim to unveil the mechanisms governing the competition between the two fracture modes observed in the experiments. In the calculations, the brittle cracking of amorphous films is modeled using the cohesive zone framework and the shear banding induced fracture in films is characterized by a simple local fracture criterion. The results show that brittle cracking of amorphous films occurs in the case of thin films, while the shear banding induced fracture dominates in the case of thick films. For the films with intermediate thickness, the mixed fracture modes are observed. Such a film thickness effect predicted by numerical simulations is consistent with the experimental observations. We further reveal that the film thickness effect is related to substrate constraint. In addition, it is identified that the cohesive strength and toughness of amorphous films also play an important role in controlling the fracture modes of the film/substrate systems.

We briefly review the electrical-optical response of materials to radiative forcing within the formalism of the Kramers-Kronig relations. A commensurate set of criteria is described that must be met by any frequency-domain model representing the time-domain response of a real (i.e., physically possible) material. The criteria are applied to the Brendel-Bormann (BB) oscillator, a model that was originally introduced for its fidelity at reproducing the non-Lorentzian peak broadening experimentally observed in the infrared absorption by thin amorphous films but has since been used for many other common materials. We show that the BB model fails to satisfy the established physical criteria. Taking an alternative approach to the model derivation, a physically consistent model is proposed. This model provides the appropriate line-shape broadening for modeling the infrared optical response of thin amorphous films while adhering strictly to the Kramers-Kronig criteria. Experimental data for amorphous alumina (${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$) and amorphous quartz silica (${\mathrm{SiO}}_{2}$) are used to obtain model parametrizations for both the noncausal BB model and the proposed causal model. The proposed model satisfies consistency criteria required by the underlying physics and reproduces the experimental data with better fidelity (and often with fewer parameters) than previously proposed permittivity models.

Based on the framework of long-range empirical formulas, the interatomic potentials were constructed for the Ni-Nb-Mo (fcc-bcc-bcc) and Ni-Zr-Mo (fcc-hcp-bcc) ternary metal systems. Applying the constructed potentials, atomistic simulations were performed to predict the energetically favored glass formation regions (GFRs) in the respective composition triangles of the systems. In addition, the amorphization driving forces (ADFs), i.e., the energy differences between the solid solutions and disordered phases, were computed and appeared to correlate with the so-called glass forming abilities. To verify the atomistic prediction, ion beam mixing with nano-multiple-metal-layers was carried out to produce ternary amorphous films. The results showed that the composition of ternary amorphous films obtained by ion beam mixing all locate inside the GFRs, supporting the predictions of atomistic simulations. Interestingly, the minimum ion dosage required for amorphization showed a negative correlation with the calculated ADF, implying that the predicted amorphization driving force could be an indicator of the glass formation ability.

WOS: 000452762000010, Amorphous films of two varieties of zinc stannate (ZnSnO3 and Zn2SnO4) have been considered that were fabricated by radio-frequency sputtering of ceramic compound targets containing ZnO and SnO2 in 1: 1 and 2: 1 ratios. The elemental and phase compositions of the films and their optical and electrical parameters were determined. The transparency of the films in the visible spectral range is on average 87%. Zinc stannate amorphous films have a high electrical conductivity in contrast to amorphous ZnO and SnO2. This phenomenon, which makes it possible to use zinc stannate amorphous films in transparent and flexible electronics, is explained., Russian Foundation for Basic Research and TUBITAK [12-02-91373_CT_a], This study was supported in part by the Russian Foundation for Basic Research and TUBITAK, grant no. 12-02-91373_CT_a.

For a high magnetic refrigeration efficiency, a large change of magnetic entropy (−ΔS M ) associated with a high relative cooling power (RCP) are highly desirable. Here, the ion implantation is used to enhance both parameters in FeZr amorphous films. A considerable enhancement of both (−ΔS M ) and RCP, from 0.66 to 1.01 J/kg K and 84.5 to 155.5 J/kg respectively, for the as-grown sample compared to the C-implanted sample is obtained for a magnetic field change of µ 0 ΔH=1.5 T. The increase of (−ΔS M ) and RCP values, are attributed to the increase of the magnetization and the chemical inhomogeneity, respectively upon C implantation.

Purpose: Thin films of Ge and Sb chalcogenides are suitable for creation of PCM devices that works on the basis of reversible “amorphous phase ↔ crystalline phase” transition. In this paper the results of the investigations temperature dependences electric resistance R and optical transmission θ of Sb x Te 100- x amorphous films are reported. Methods: Nonisotermal crystallization of Sb x Te 100- x films was investigated by the method, which allows simultaneously measurements of optical transmission and electric resistance on the one samples. Investigations of R ( T ) and Q ( T ) dependences were carried out in the temperature range of 290-550 K. Heating rates were equal 0.75, 1.8 and 4.5 K/min. Results and discussion: It was established that crystallization of films is accompanied by a sharp decrease of R and θ . The change of resistance rich of 3-4 orders higher of magnitude. Parameters of phase transition (the starting temperature from amorphous to crystalline state and temperature range of transition) depends on the chemical composition of the films and the heating rate. The results testifies about possibility to use the films of Sb-Te system for memory cells and temperature sensors production.

The Al0.25CrCoFe1.25Ni1.25 high-entropy alloys (HEAs) are coated with Ni–P amorphous films with a thickness of 35 μm. The as-cast HEAs have a yielding strength of 52 MPa. In contrast, the yielding strength of coated HEAs exhibits over 130 MPa, with a 160% improvement. A considerable total tensile strain as high as about 50% is detected in the as cast and coated HEAs. In addition, Ni–P coatings have a stable passive characteristic and form a thick passive film, suggesting that Ni–P coatings provide an effective barrier against active dissolution process. The current Ni–P coated HEAs combine the excellent mechanical and electrochemical properties.

We report on the effect of carbon ion-implantation on the critical behavior of Fe93Zr7 amorphous films. Both the as-grown and carbon-implanted Fe93Zr7 samples exhibit a second order ferromagnetic to paramagnetic transition. The critical exponents were investigated through different techniques such as modified-Arrott plot, the critical isotherm analysis and the Windom scaling relation. Analysis of the critical behavior was presented in terms of the magnetocaloric effect around TC. While there is a significant increase of the magnetization and TC upon C-implantation, the critical exponents were only slightly affected by implantation and were in line with those of the 3D-Heisenberg model.

Amorphous films of HfO₂ are prepared by laser ablation of Hf target in an oxygen atmosphere. Its crystallization was performed under the electron beam impact in a column of electron microscope. Formation and growth of HfO₂ crystals are investigated in situ. The transformation kinetic curves are plotted on the basis of a frame-by-frame analysis of the video recorded flick during the film crystallization. According to the structural and morphological features, the phase transformation corresponds to the dendrite polymorph crystallization and can be either single-stage or two-stage in nature. In the latter case, the size-phase effect takes place, consisting in the fact, that when the crystal of orthorhombic modification of HfO₂ reaches a critical size (~0.2 μm), it splits into domains with orthorhombic and monoclinic crystal lattices. The kinetic parameters of the crystallization are determined and it is shown, that the quadratic dependence of the fraction of the crystalline phase on time takes place. The average value of the relative length for the dendrite polymorphic crystallization is about 3075. The phase transition from the amorphous state to the crystalline one is accompanied by increasing of the relative density of matter of the film by about 2.5 %. The crystallized film consists predominantly of dendrites of the monoclinic modification of HfO₂.

Using chemical plating, Ni-P films were successfully coated on Ti 20 Zr 20 Hf 20 Be 20 Cu 20 high-entropy bulk metallic glasses (HE-BMGs), and presented an enhancive adhesion as well as a higher deposition rate on account of the chemical pretreatment before electroless plating. With the coating, the plastic strain of the HE-BMGs is increased up to 5.7%, which is 3.2 times of 1.8% of the bare pillars. It shows that the adhesive coating with a thickness of 10 µm leads to a plasticity enhancement of HE-BMGs via the dispersive impact of coating on the concentrated stress. In addition, the coating leads to more homogeneous regions where shear banding may take place and offers a preventible action for the rapid propagation of shear bands.

In metallic glasses (MGs), plastic deformation at room temperature is dominated by highly localized shear bands. Here we report the non-localized deformation under tension in Cu Zr multi-layer MGs with a pure amorphous structure using large-scale atomistic simulations. It is demonstrated that amorphous samples with high layer numbers, composed of Cu64Zr36 and Cu40Zr60, or Cu64Zr36 and Cu50Zr50, present obviously non-localized deformation behavior. We reveal that the deformation behavior of the multi-layer-structured MG films is related but not determined by the deformation behavior of the composed individual layers. The criterion for the deformation mode change for MGs with a pure amorphous structure, in generally, was suggested, i.e., the competition between the elastic-energy density stored and the energy density needed for forming one mature shear band in MGs. Our results provide a promising strategy for designing tensile ductile MGs with a pure amorphous structure at room temperature.