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Compared to the commercial soft-magnetic alloys, the high saturation magnetic flux density (B s) and low coercivity (H c) of post-developed novel nanocrystalline alloys tend to realize the miniaturization and lightweight of electronic products, thus attracting great attention. In this work, we designed a new FeNiBCuSi formulation with a novel atomic ratio, and the microstructure evolution and magnetic softness were investigated. Microstructure analysis revealed that the amount of Si prompted the differential chemical fluctuations of Cu element, favoring the different nucleation and growth processes of α -Fe nanocrystals. Furthermore, microstructural defects associated with chemical heterogeneities were unveiled using the Maxwell–Voigt model with two Kelvin units and one Maxwell unit based on creeping analysis by nanoindentation. The defect, with a long relaxation time in relaxation spectra, was more likely to induce the formation of crystal nuclei that ultimately evolved into the α -Fe nanocrystals. As a result, Fe84Ni2B12.5Cu1Si0.5 alloy with refined uniform nanocrystalline microstructure exhibited excellent magnetic softness, including a high B s of 1.79 T and very low H c of 2.8 A/m. Our finding offers new insight into the influence of activated defects associated with chemical heterogeneities on the microstructures of nanocrystalline alloy with excellent magnetic softness. [ABSTRACT FROM AUTHOR]

The influence of modernized three-electrode ion-plasma sputtering of a complex Fe–Si–B– (Cu, Nb)/(Ni, Mo) target on the structure and properties of sputtered films was studied. The formation of amorphous and nanocrystalline phases in Fe73Si15.8B7.2-(Cu, Nb)4 and Fe78.5Si6B14-(Ni, Mo)1.5 films with a coherent scattering region size of 1.6 nm and 12 nm, respectively, was established as a result of a modernized three-electrode ion - plasma sputtering. The thermal stability of metastable states of films as well as electrical and magnetic properties of freshly prepared and heat-treated films has been investigated. The conditions for obtaining films with low values of the temperature coefficient of electrical resistance (−0.9∙10−5 K−1) and coercive force (HC ∼11 A/m) have been determined. [ABSTRACT FROM AUTHOR]

Data are presented on the effect of high-frequency three-electrode ion-plasma sputtering and modernized three-electrode ion-plasma sputtering of a Fe–Ag–Pt complex target on the structure and properties of deposited films. The formation of nanocrystalline films with a size of the coherent scattering region of 3.5 nm during high-frequency ion-plasma spraying has been established. With the modernized three-electrode ion-plasma sputtering, a nanocrystalline phase is formed with a coherent scattering region size of 3 nm and higher temperature stability, up to 660 K. There were investigated the thermal stability of the metastable states of the Fe–Ag–Pt films; the electro- and hysteresis magnetic properties of freshly prepared and heat-treated films. The conditions for obtaining films with low values of the temperature coefficient of electrical resistance (∼5 × 10−5 K−1) and coercive force (Hc ∼ 12 kA/m) are determined. [ABSTRACT FROM AUTHOR]

Mechanical cycling is one of the effective methods to rejuvenate metallic glasses (MGs) and improve their mechanical properties. The anelastic origin of the rejuvenation by mechanical cycling in a La30Ce30Ni10Al20Co10 MG was investigated via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). We demonstrate that mechanical cycling promotes the activation of flow defects with short relaxation times, leading to anelastic strains and therefore considerable energy storage, which manifests itself as larger relaxation enthalpy on the DSC curves of MGs. However, the MGs release the excess relaxation enthalpy caused by anelastic strain with time, thus suppressing atomic mobility and elevating β relaxation activation energies. The strategy of mechanical cycling at small strains, as demonstrated in the current work, can expand the energy states of MGs over a wide range of relaxation enthalpies. [ABSTRACT FROM AUTHOR]

Many works on topological insulators have focused on periodic lattice systems; where short- and long-range order is considered. Here we construct a two-dimensional amorphous photonic crystal with short-range order and a controllable level of long-range order and experimentally investigate the transport of topological edge states in this amorphous system. We demonstrate that topology properties remain constant with unidirectional edge state propagation; immune to specific disorder strength. The partition phenomena of edge states are also observed at the intersection of four topological channels in microwave experiments. This proposed amorphous configuration provides new opportunities to explore the relationship between short-range order and topology and may alleviate the fabrication difficulties of topological optical devices for practical applications. [ABSTRACT FROM AUTHOR]

We successfully fabricate high-entropy alloys and amorphous alloy composites by adopting the proposed ultrasonic vibration method. The low-stress, low-temperature method enables us to create composites that combine both amorphous and crystalline properties. Microscopic observations and computed tomography measurements indicate good bonding quality without pores or cracks in the composites. Due to the unique structure which mixes soft and rigid phases, the composite exhibits improved mechanical performance compared to that obtained from a pure single phase. Our results are promising for the manual design and fabrication of smart materials containing multiple phases and compositions. [ABSTRACT FROM AUTHOR]

In this paper magnetic relaxation processes in iron based amorphous alloys are examined in order to determine thermal/time instability of magnetic properties at room temperature. It was shown that the reversible component of magnetic relaxation in Fe74Cu1Cr3Si13B9 alloy can be well described by the coupling model usable for diffusion in strongly correlated systems. The proposed approach allows monitoring initial stages of structural relaxation. [ABSTRACT FROM AUTHOR]

An approach for determination of the onset crystallization time ( t ons ) at isothermal annealing of metallic glasses similar to that used in the DSC analysis for the onset crystallization temperature is proposed. The analysis performed in the framework of the Kolmogorov-Johnson-Mehl-Avrami model has shown that the volume fraction transformed at t ons ( X ons ) increases from 0 to 0.05 with the Avrami exponent increasing from 1.5 to 12. It has been found that the values of X ons determined from the experimental kinetic crystallization curves for the Fe 85 B 15 glass at 628 K, for the Fe 40 Ni 40 P 14 B 6 glass at 662, 649 and 617 K and for the Fe 40 Co 40 P 14 B 6 glass at 695 K are in good agreement with the calculated ones. New possibilities for analysis of nucleation behavior in glasses using the relation established between the kinetic and structural data are discussed. [ABSTRACT FROM AUTHOR]

The structural properties of amorphous GaSe 9 thin films produced by vacuum evaporation were investigated using the EXAFS technique and the cumulant expansion method. Structural parameters such as average coordination numbers and interatomic distances, disorder and asymmetry of the partial pair distribution functions g ij ( r ) were obtained and compared to those found in the amorphous GaSe 9 alloy used as precursor in the evaporation technique. Results indicate that structural units present in GaSe 9 evaporate without dissociation, showing the stability of this alloy. [ABSTRACT FROM AUTHOR]

In this study, amorphous Bi(SeTe) glasses with (0 ≤ x ≤ 12) were prepared by the usual melt quench technique. Thin films of these glasses were deposited onto glass substrates by using thermal evaporation method. The amorphous nature of the as-prepared films was confirmed by X-ray diffraction. Structural investigations were performed using X-ray energy-dispersive spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy. The transmission spectra of these films were measured at normal incidence in the wavelength range 400-2500 nm. Swanepoel's analysis of the maxima and minima of the interference fringes was used to determine the film thickness, the complex index of refraction and the extinction coefficient with high accuracy. The dispersion of the refractive index was well discussed in terms of the single oscillator model (Wemple and DiDomenico). It was found that increasing Bi content led to the increase in refractive index and the extinction coefficient of the Bi(SeTe) films, while the optical band gap decreased. The mechanism of the optical absorption in Bi(SeTe) films obeyed the allowed indirect optical transition. The decrease in optical gap with increasing Bi content was discussed in terms of the chemical bond approach. [ABSTRACT FROM AUTHOR]

The influence of pulse fluences on phase transition dynamics processes of amorphous Ag 8 In 14 Sb 55 Te 23 (AgInSbTe) thin films induced by single nanosecond laser pulses were studied by transient optical reflectivity measurements. Phase transition driven by nanosecond laser pulses have been achieved in a proper fluence range on AgInSbTe thin films. It was found that phase transition dynamics induced by nanosecond laser pulses was a multi-stage optical evolution process involving melt, solidification, recalescence, and recrystallion. The dependence of time parameters and normalized reflectivity change determined by optical evolution curve on laser pulse fluence was studied and analyzed. [ABSTRACT FROM AUTHOR]

Thermal stability, structural changes and nanocrystallization kinetics of the Fe 80 B 14 Si 6 and Fe 45 Ni 19.4 Co 8.5 Cr 5.7 Мо 1.9 B 14 Si 5.5 amorphous alloys under continuous heating and isothermal annealings as well as the changes of microhardness caused by the phase transitions have been experimentally studied by a combination of X-ray diffraction analysis, differential scanning calorimetry, by measurements of electrical resistance and microhardness. The partial replacement of Fe in the Fe 80 B 14 Si 6 alloy by a number of transition metals results in lowering of the onset crystallization temperature, facilitating the nanocrystal forming tendency, and enhancement of the microhardness values of the samples in the non-equilibrium structural states. The temperature dependencies of effective diffusion coefficients governing nanocrystallization are determined by approximation of the experimentally measured changes of the α-Fe nanocrystal sizes and the kinetic curves of nanocrystallization within the appropriate analytical models. The essentially lower thermal stability of the Fe 45 Ni 19.4 Co 8.5 Cr 5.7 Мо 1.9 B 14 Si 5.5 amorphous alloy compared with that of Fe 80 B 14 Si 6 is associated with about two orders of magnitude lower effective diffusivity at the onset crystallization temperatures. From comparison of the rates of growth of α-Fe nanocrystals and their numbers of volume density in nanocomposite structures, it is suggested that the thermal stability of the former amorphous alloy is limited by slow diffusion-limited growth, while that of the latter one is controlled by nucleation. [ABSTRACT FROM AUTHOR]

The present article deals with the differential thermal analyses (DTA) study of Se-Te glasses containing Sn. DTA runs are taken at six different heating rates (5, 10, 15, 18, 20, and 22 K min−1). The crystallization data are examined in terms of modified Kissinger, Mahadevan method, and Augis and Bennett approximation for the non-isothermal crystallization. Results of DTA under non-isothermal conditions on the glasses of the Se80Te20-- xSn x ( x = 3 and 9) are reported and discussed at different heating rates. The glass transition temperatures ( Tg), the onset crystallization temperatures ( Tc), and the peak temperature of crystallization ( Tp) were found to be dependent on the compositions and the heating rates. From the dependence on heating rates of ( Tg) and ( Tp) the activation energy for glass transition ( Eg) and the activation energy for crystallization ( Ec) are calculated and their composition dependence discussed. [ABSTRACT FROM AUTHOR]

Atomic structure of amorphous silicon consistent with several reported experimental measurements has been obtained from annealing simulations using electron density functional theory calculations and a systematic removal of weakly bound atoms. The excess energy and density with respect to the crystal are well reproduced in addition to radial distribution function, angular distribution functions, and vibrational density of states. No atom in the optimal configuration is locally in a crystalline environment as deduced by ring analysis and common neighbor analysis, but coordination defects are present at a level of 1%–2%. The simulated samples provide structural models of this archetypal disordered covalent material without preconceived notion of the atomic ordering or fitting to experimental data.

Previous studies show that there are some similarities between glass transition and melt process for metals. We assume that the glass transition occurs when the amplitude of atomic vibrational motions exceeds a critical fraction of the atomic spacing, and find that the glass transition temperature of metallic glass is proportional to the product of its Young's modulus and molar volume. The finding indicates that the glass transition is associated with the vibrational motions of atoms, and a Lindemann-type criterion holds for the glass transition temperature of metallic glasses. [ABSTRACT FROM AUTHOR]

We report the acquisition of strong blue to red photoluminescence (PL) from a-SiN xO y thin film that was prepared by plasma enhanced chemical vapor deposition at room temperature. By increasing the flow rate ratio ( R) of silane (SiH4) to ammonia (NH3), the luminescent peak position can be tunable in the visible range from 440 to 590 nm, and shown to be independent of temperature as revealed by temperature-dependent PL investigation. The Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectra (XPS) were employed to clarify the relationship between the bonding configuration and PL characteristics. Based on the existence of N-Si-O bond arrangement evidenced in FTIR spectra, the deconvolution of the Si 2p peak was carried out to yield five component peaks corresponding to Si-N4, N3-Si-O, N2-Si-O2, N-Si-O3, and Si-O4. The increase of PL intensity is suggested to be closely related to increased concentration of N x-Si-O y bonds. All the results obtained from temperature-dependent PL spectra, FTIR spectra, and XPS spectra disclosed that the light emission from a-SiN xO y film can be originated from recombination via luminescent centers associated with N x-Si-O y bonding configuration, and the redshift of PL peak with the increase of R may arise from integral effect of N x-Si-O y bonding configuration transformation and valence band maximum upward shift. [ABSTRACT FROM AUTHOR]

We deposited amorphous indium gallium nitride (a-In xGa1- xN) films at room temperature by reactive radio frequency sputtering with GaN and InN targets and investigated the change of their properties from thermal annealing at annealing temperatures, Ta, below 200 °C. A large change in the indium and nitrogen composition ratios was not observed by thermal annealing at a Ta below 200 °C. In the X-ray diffraction patterns of the films annealed at a Ta below 200 °C, no perceivable peaks assigned to crystalline In xGa1- xN were found. The photoconductivty, σp, increased with an increase in Ta. On the other hand, the increase of the dark conductivity, σd, was very small with an increase in Ta below 200 °C. As a result, the photosensitivity, σp/ σd, increased from 252 to 2500 by thermal annealing at a Ta of 200 °C. [ABSTRACT FROM AUTHOR]

The influence of implanted hydrogen (up to a concentration level of 3 at. %) on the microstructure of silicon (Si) materials is investigated by Fourier transform infrared spectroscopy as well as by effusion of hydrogen and of (low dose) implanted helium. Three materials of low original hydrogen concentration, crystalline Si, electron beam evaporated amorphous Si, and plasma-deposited hydrogenated amorphous Si (using high deposition temperature) were investigated. Significant differences between crystalline and amorphous materials were observed. In crystalline Si, implanted hydrogen is found to generate multivacancies that trap diffusing helium while this is not the case in amorphous Si. Accordingly, cavities where hydrogen is located in amorphous Si must be smaller than divacancies. Those cavities in amorphous Si, present from the growth process, that trap helium tend to disappear when the implanted hydrogen concentration increases. Annealing of the materials up to temperatures of 575 °C was also studied. No significant change in the density of voids (trapping helium) occur but in case of crystalline Si the bonding sites of hydrogen as well as the diffusion paths of helium change. [ABSTRACT FROM AUTHOR]

We have investigated the preparation of crystalline germanium films by the solid phase crystallization (SPC) of amorphous germanium (a-Ge) precursor on single crystalline silicon substrates. The a-Ge precursor easily incorporates the impurities from the surface exposed to the air, and the impurities affect the crystallinity after the SPC. In the a-Ge precursor prepared by Knudsen-cell evaporation, the preferential crystalline growth following the Si substrates is disturbed by the high density of impurities and the random crystalline structures are formed. The a-Ge precursors prepared by electron beam evaporation have high impurity concentrations only near the surface because the impurity diffusion is slow because of the relatively high density. The preferential growth is successfully obtained in a-Ge precursor prepared on n-type Si substrates, although the random crystallization is slightly observed on p-type Si substrates. By sufficiently reducing the impurity concentrations by avoiding the air exposure, the preferential growth can be promoted on p-type Si substrates. The impurity incorporation because of the air exposure is sufficiently reduced for the preferential growth by covering a-Ge with a-Si blocking layers. This method is effective for future practical applications of SPC Ge films. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The paper investigates the dependence of the optical properties on cation concentration of amorphous-like indium gallium zinc oxide thin films (In Ga Zn1−x O1+0.5x−δ ) with various (In+Ga)/(In+Ga+Zn) and Ga/(In+Ga) ratios obtained by pulsed laser deposition. X-ray reflectivity and spectroscopic ellipsometry thickness results were in good agreement. The proportionality between density and the refractive index in the transparency range is evidenced. The extracted physical parameters are clearly influenced by the variation of cation concentration. [Copyright &y& Elsevier]

We report on modifications of 280-nm thin polycrystalline CrN layers caused by vanadium ion implantation. The CrN layers were deposited at 150°C by d.c. reactive sputtering on Si(100) wafers and then implanted at room temperature with 80-keV V+ ions to fluences of 1×1017 and 2×1017 ions/cm2. Rutherford backscattering spectroscopy, cross-sectional transmission electron microscopy, and X-ray diffraction were used to characterize changes in the structural properties of the films. Their optical and electrical properties were analyzed by infrared spectroscopy in reflection mode and electrical resistivity measurements. CrN was found to keep its cubic structure under the conditions of vanadium ion implantation used here. The initially partially non-metallic CrN layer displays metallic character under implantation, which may be related to the possible formation of Cr1−x V x N. [ABSTRACT FROM AUTHOR]

Abstract: A foil strip made of amorphous alloy Fe70Cr15B15 was loaded with the tensile stress ∼500MPa and remained with the ends kept fixed during 2h. The statistical characterization of the temporal transformation of the sample surface relief was performed using the autocorrelation functions computed for one-dimensional profiles measured along the axis of loading. The profiles were recorded with the help of the scanning tunneling profilometer. The acquisition time of a single scan was about 0.5min. The calculated autocorrelation function of the profile depths in the original foil shows a long-range (∼2×103 nm) correlation between relief components. The application of the tensile stress causes an immediate, significant increase of the roughness depth from ∼40–50nm to 100–200nm with a corresponding drop of the correlation length to 0.7×103 nm. The surface relief does not remain stable during loading but varies as a result of the competitive processes, such as microcrack growth, stress-induced flattening, and shearing. The variability of the deformation process in the ‘structureless’ amorphous alloy is due to the dynamical non-uniformity of the multi-focal damage nucleation. [Copyright &y& Elsevier]

Abstract: Detection of scintillation light from LSO (Lutetiumoxyorthosilicate) crystals used in positron emission tomography (PET) is traditionally based on photo-multipliers. The proposal is to develop a novel photo-sensor, which is based on vertically integrating an hydrogenated amorphous silicon (a-Si:H) film on a pixel readout chip. The a-Si:H film is deposited with a n–i–p diode structure. The ASIC (Application Specific Integrated Circuit) performs both signal amplification and readout processing. The advantage of such an approach is the extremely compact and low-cost design, together with ultra-low noise signal retrieval. In addition the a-Si:H offers the technological advantage of direct deposition on the wafer thanks to the low deposition temperature. The article presents the results of quantum efficiency measured on different types of a-Si:H photodiodes deposited on glass (DC measurement) and CMOS circuit (AC measurement). Quantum Efficiency (QE) up to 80% has been measured at the wavelength of interest for the optimized photodiodes. [Copyright &y& Elsevier]