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The incipient plasticity of an amorphous solid represents the onset of shear deformation, which is a stochastic progress closely related to microstructure evolution. It is well known that the cooling rate plays a crucial role in the microstructure evolution of a glass. Nevertheless, how the cooling rate affects the incipient plasticity is still unclear. In this work, the incipient plastic deformation of the amorphous phase in Cu 47.5 Zr 48 Al 4 Nb 0.5 bulk metallic glass composites (BMGCs) cast with different cooling rates is systematically studied. The incipient plasticity of the glassy matrix of the BMGCs is found to occur via a first displacement burst, the occurrence of which is more stochastic as the cooling rate decreases. According to the auto-correlation functions and cooperative shear model, the stochastic behavior is attributed to the effects of the cooling rate on the initial free volume and subsequent activated shear transformation zones (STZs). A higher content of free volume is present in the glassy matrix of the studied samples cooled at a faster rate, which facilitates the operation of STZs. Moreover, the larger incipient burst size is correlated with the higher content of free volume and larger STZs in the glassy matrix. The larger STZs result in more preferable propagation of multiple shear bands, leading to less stochastic deformation and more obvious plastic deformation. This study provides further understanding on the incipient plasticity of glassy matrix in BMGCs. Image 1 • Hardness and elastic modulus of amorphous phase are higher at a lower cooling rate. • The deformation of amorphous phase is more stochastic as cooling rate decreases. • Larger shear transformation zones facilitate the formation of multiple shear bands. • Initial free volume is the dominant role in mechanical behavior of amorphous phase. [ABSTRACT FROM AUTHOR]

The plastic deformation of metallic glasses (MG) is well-known to occur via shear transformation zones (STZs) on the scale of atomic clusters, yet fracture of MG takes place via shear bands of the micron scale. So far, understanding on how the operation of STZs leads to shear localization and fracture remains limited. In this work, tensile tests on Cu/Zr-based MG micro-wires show that both the first-yield and fracture stress exhibit the Weibull distribution, and fractography reveals that shear localization in the form of intense shear bands leads to shear fracture. Molecular dynamics (MD) simulations show that shear bands form via the correlated emergence and operation of discrete STZs close to one another. To describe how the stochastic yet correlated occurrence of the discrete STZs leads to shear localization, a model is constructed to relate the probability of the successive operation of discrete STZs, to their nucleation density. The model predicts that, if nucleation density of the STZs grows along the strain path, as prior shear events triggers the emergence of new STZs, then successive occurrence of discrete shear events speeds up rapidly to an asymptotic state which is exactly the condition of shear localization and shear banding. Furthermore, the MD results suggest an exponential growth law for the occurrence of the STZs along the strain path, which also gives predictions in good agreement with the experimental Weibull distributions of the first-yield stress of Cu/Zr-based MGs. • Tensile tests show that both first-yield and fracture stress of Cu/Zr-based MG micro-wires exhibit Weibull distributions. • MD simulations show that shear bands form via the correlated formation of successive shear zones of atomic sizes. • A statistical model is proposed to describe the survival probability against successive occurrence of discrete shear events. • The model predicts that shear localization is a consequence of acceleration of shear event occurrence, as in MD simulation. • An exponential growth law for the shear event occurrence agrees with both the MD and experimental results. [ABSTRACT FROM AUTHOR]

The microstructure, optical and electrical properties of sputtering-derived HfGdO high-k gate dielectric thin films as a function of the Gd doping content have been systematically investigated. X-ray diffraction (XRD) measurements have indicated that Gd doping can form a new stable cubic phase. The optical band gap of the HfGdO gate dielectrics increases gradually from 5.82 to 6.14 eV as the Gd doping concentration increases. The electrical properties, such as permittivity, oxide trapped charge density, border trap charge density and leakage current density of samples, are determined using a semiconductor device analyzer. The formation mechanism of leakage current is also discussed in detail. In addition, the interfacial properties of HfGdO/Si gate satcks were tested to establish the electrical properties. The excellent optoelectronic properties, such as the optical band gap of 5.95 eV, leakage current density of 8.33 × 10 −8 A/cm 2 at a bias voltage of 2 V, oxide trapped charge density of −1.06 × 10 12  cm −2 and a border trap charge density of zero and optimized interfacial properties were observed in the HfGdO thin films with sputtering power of 30 W, indicating that it may become a potential high-k gate dielectric in future complementary metal oxide semiconductor (CMOS) devices. [ABSTRACT FROM AUTHOR]

In this work, the interface chemistry and the reduction of GaAs surface species by using (NH 4 ) 2 S solution prior to Gd-doped HfO 2 (HGO) thin film deposition and the removal of Ga Oxides and elemental As by rapid thermal annealing (RTA) have been investigated by X-ray photoelectron spectroscopy (XPS). Additionally, the effect of the surface passivation and rapid thermal annealing on the electrical properties of MOS capacitors based on sputtering-derived HGO as gate dielectric on GaAs substrate has been detected by means of capacitance-voltage ( C-V ) and leakage current density-voltage ( J-V ) measurements. Based on electrical analysis, it can be noted that the constantly improvement of electrical properties, such as the decreases of flat band voltage (V fb ), hysteresis (ΔV fb ), oxide charge density (O ox ), border trapped oxide charge density (N bt ) and leakage current density, have been observed. Especially, the dielectric constant of 16.72, flat band voltage V fb of 1.19 V, hysteresis ΔV fb of 0.04 V, leakage current density of 1.54 × 10 −5 A/cm 2 at bias voltage of 1 V, total positive charge density and border trap charge density of 6.09 × 10 12 cm −2 and 2.54 × 10 11 cm −2 , respectively render 600 °C-annealed HGO thin films, potential high-k gate dielectrics in future CMOS devices. [ABSTRACT FROM AUTHOR]

The microstructure, optical and electrical properties of HfTiO high-k gate dielectric thin films deposited on Si substrate and quartz substrate by RF magnetron sputtering have been investigated. Based on analysis from x-ray diffraction (XRD) measurements, it has been found that the as-deposited HfTiO films remain amorphous regardless of the working gas pressure. Meanwhile, combined with characterization of ultraviolet-visible spectroscopy (UV–vis) and spectroscopy ellipsometry (SE), the deposition rate, band gap and optical properties of sputtered HfTiO gate dielectrics were determined. Besides, by means of the characteristic curves of high frequency capacitance–voltage ( C – V ) and leakage current density–voltage ( J – V ), the electrical parameters, such as permittivity, total positive charge density, border trap charge density, and leakage current density, have been obtained. The leakage current mechanisms are also discussed. The energy band gap of 3.70 eV, leakage current density of 1.39×10 −5 A/cm 2 at bias voltage of 2 V, and total positive charge density and border trap charge density of 9.16×10 11 cm −2 and 1.3×10 11 cm −2 , respectively render HfTiO thin films deposited at 0.6 Pa, potential high-k gate dielectrics in future CMOS devices. [ABSTRACT FROM AUTHOR]

• Fe 84 Zr x B 16- x (x = 6, 8, and 10 at. %) alloys show pronounced β relaxation characteristic. • A positive correlation between the β relaxation and structural heterogeneity appears in Fe-based amorphous alloys. • With increased Zr/B ratio, β relaxation is easily activated and structure becomes more heterogeneous. • Alloys with easily activated β relaxation or more heterogeneous structure possess poor soft magnetic properties. Dynamic relaxation is an universal feature in amorphous alloys. However, few studies have been conducted on β relaxation of Fe-based amorphous alloys as most of them have insignificant β relaxation characteristics. In this work, the variation in β relaxation, structural heterogeneity, and soft magnetic properties are investigated in Fe-Zr-B amorphous alloys with pronounced β relaxation. β relaxation and structural heterogeneity are characterized by the ratio of β and α relaxation temperature (i.e., T β /T α) and correlation length, respectively. With the increase of Zr/B ratio, the value of T β /T α and the correlation length tend to decrease. Alloys with easily activated β relaxation or more heterogeneous structure possess poor soft magnetic properties, i.e., a significant reduction in saturation magnetic flux density and an increase in coercivity. [ABSTRACT FROM AUTHOR]

• Successful preparation of Fe 3 O 4 /PbZr 0.2 Ti 0.8 O 3 /Zn 0.95 Co 0.05 O multiferroic heterostructure. • Magnetic and resistive states of heterostructure are synchronously regulated by polarization bias at room temperature. • Significant enhancement of room-temperature magnetoelectric coupling effect is achieved in multiferroic heterostructure. • Fe 3 O 4 /PbZr 0.2 Ti 0.8 O 3 /Zn 0.95 Co 0.05 O multiferroic heterostructure presents four distinct magnetoresistances. A novel multiferroic heterostructure composed of Fe 3 O 4 /PbZr 0.2 Ti 0.8 O 3 (PZT)/Zn 0.95 Co 0.05 O(ZCO) is prepared on the Pt(1 1 1)-Ti-SiO 2 -Si substrate in this work to achieve the synchronous electric regulation on magnetic and resistive states at room temperature. When the polarization direction of the PZT layer is reversed with the write voltage, the depletion or accumulation of oxygen vacancies is formed at the PZT/ZCO interface, exhibiting the resistance switching between high and low resistive states with a ratio up to 1.19 × 104. Meanwhile, based on the interfacial charge effect and bound magnetopolaron (BMP) theory, magnetic modulation with a magnetoelectric (ME) coupling coefficient up to 133.2 Oe/V is realized at room temperature. More interestingly, by measuring the magnetoresistance, four distinct resistance states are displayed in this multiferroic structure with the ferroelectric reversal. Our results show that the multiferroic system containing both ferromagnetic and diluted magnetic semiconductor can simultaneously realize magnetoelectric coupling and resistance switching at room temperature. The magnetic signal can also be converted into an electrical signal based on the magnetoresistance effect. [ABSTRACT FROM AUTHOR]

The plastic stability of bimetals composed of a Ti-based metallic glass composite (MGC) and a pure titanium (PT) under tension has been investigated. The results reveal that the plastic stability of the MGC/PT bimetal is strongly dependent on the thickness fraction of the MGC: when the thickness fraction of the MGC decreases to a critical value, a homogeneous plastic deformation occurs in the MGC/PT bimetals, i.e. the strain localization and necking of the MGC is effectively suppressed. This unique phenomenon is explained using the normalized strain-hardening rate, and the quantitative relationship between the normalized strain-hardening rate of the MGC/PT bimetals and the thickness fraction of the MGC is thereby established. [ABSTRACT FROM AUTHOR]

• The nanoscale structural heterogeneity and magnetic properties were analyzed by atomic force microscopy and Mössbauer spectroscopy. • The nanoscale structural heterogeneity of Fe 80 Si 9 B 11 amorphous alloy attenuates monotonically with a decrease in cooling rate. • The annihilation of flow units induces the enhancement in ferromagnetic exchange interaction and weakening of magnetic anisotropy. • The ameliorated magnetic properties with decreasing cooling rate can be attributed to the degeneration of nanoscale structural heterogeneity. Despite that the nanoscale structural heterogeneity of amorphous alloys has been confirmed by advanced experimental observations and theoretical simulations, the underlying link between the structural heterogeneity and magnetic properties remains poorly known. In this work, the effect of cooling rate on the nanoscale structural heterogeneity and magnetic properties of Fe 80 Si 9 B 11 amorphous ribbons (Fe-Si-BAR) was studied by atomic force microscopy and Mössbauer spectroscopy. The results show that the degeneration of nanoscale structural heterogeneity substantially induces an improvement in soft magnetic properties with decreasing cooling rate. Specifically, the volume fraction of flow units reduces significantly with the decrease of cooling rate, and some of the flow units annihilate and transform to the ideal elastic matrix. The structural densification and reduction of the number density of quasidislocation dipole result in an enhancement in ferromagnetic exchange interaction and weakening of magnetic anisotropy. Therefore, the saturation magnetic flux density increases and coercivity decreases with reducing cooling rate. Our results provide new insight into understanding the structural mechanism in the ameliorated magnetic properties of Fe-based amorphous alloys with decreasing cooling rate. [ABSTRACT FROM AUTHOR]

Abstract: The high temperatures and extended times involved with superplastic forming titanium mean that conventional die-steels are not suitable. Although dies manufactured from nickel-based alloys are used frequently, these are expensive, and more importantly, the coefficient of thermal expansion (CTE) of this materials are bigger than that of Ti–6Al–4V, which causes the dimensional inaccuracy between the dies and workpieces. The aim of this paper is to control the CTE of ZrO2–TiO2 ceramic die by adjusting the volume fraction of TiO2 and the relative density, and then controlling its’ CTE to be similar to Ti–6Al–4V alloy. In this paper, firstly, the relation between the expansion coefficient and the volume fraction of TiO2 and ceramic relative density was investigated. The results showed that with the increment of the volume fraction of TiO2, the expansion coefficient decreased. And with the rising of the relative density, the expansion coefficient increased. Secondly, based on the Turner Equation, a modified theoretical model was proposed in which the relative density of ceramic was considered. Using the model, the comparison was made between the experimental data and calculated data. The result showed that the linear CTE of ZrO2–TiO2 can be controlled by adjusting the volume fraction of TiO2 and corresponding relative density. Thirdly, to evaluate the practicability of the ZrO2–TiO2 ceramic die on superplastic forming, the ZrO2–TiO2 ceramic die (volume fraction of TiO2 is 27%, relative density is 93%) with the expansion coefficient (8.92×10−6 °C−1) similar to Ti–6Al–4V was fabricated by sintering at 1520°C for 2h. The experiment of superplastically forming Ti–6Al–4V using ZrO2–TiO2 cylinder ceramic die was carried out, also. The Ti–6Al–4V cylinder shows better shape retention, surface quality and high dimensional accuracy, and the ceramic die seems adequate for superplastically forming the high accurate Ti–6Al–4V. [Copyright &y& Elsevier]

Abstract: The film of La2/3Ca1/3MnO3 (LCMO), YBa2Cu3O7−δ (YBCO) and YBCO/LCMO bi-layer were prepared by rf off-axis magnetic sputtering technique on SrTiO3 (STO) substrate. The structures, including the surface and interfacial morphology, the interfacial diffusion and so on, have been characterized by X-ray diffraction (XRD), auger electronic energy spectroscopy (AES) and atomic force microscopy (AFM). Through a 50–200eV energy range, a single layer of YBCO shows a very small reflectance (<2%), while a single layer of LCMO shows a higher reflectance of about 25% at the energy of about 75eV, which is much higher than that of metal W. Even higher reflectance (>50%) at about 75eV has been observed in the LCMO/YBCO bi-layers. [Copyright &y& Elsevier]

We obtain analytically a universal expression of the resonant energies for any one-dimensional (1D) models with the defects having symmetric internal structures. In a 1D periodic system with the on-site energy ε0 = 0 and a nearest-neighbor matrix element t0 = 1.0, two classes of the most interesting and simplest wavefunction behaviors are numerically obtained for the resonant energies around (a) 0, ±1, (b) ±(√5-1)/2, √2, ±√3, respectively. We show that similar wavefunction behaviors can be found widely in many quasiperiodic and random systems where the delocalization phenomena are predicted. We suggest that the envelope of these wavefunctions can be generally used as a criterion of delocalization of electronic states in 1D random and quasiperiodic lattices. [ABSTRACT FROM AUTHOR]

• Magnetic properties of a Fe-Si-B amorphous alloy with stress gradient were studied. • Magnetic anisotropy and coercivity evolve separately. • Compressive stress hinders the reversible magnetization vector rotation. • Coercivity is irrelevant to the coherent stress. The magnetic properties and domain structure of a Fe 78 Si 9 B 13 amorphous alloy with a stress gradient from upper to the lower surface were investigated. We found that the magnetic properties of the samples vary significantly upon stress variation. Specifically, the magnetic anisotropy increases linearly with the maximum stress, whereas the coercivity, although higher than the one without stress, remains reasonably small. The phase contrast in magnetic force microscopy image and the fingerprint-like domains in magneto-optical Kerr microscopy images for ribbon surface with compressive stress demonstrate the presence of perpendicular anisotropy due to the magneto-elastic coupling. As a result, the compressive stress hinders the reversible magnetization vector rotation and makes the magnetization hard to be saturated. However, the stress causes no irreversible effects, neither on the domain wall movement nor on the magnetization rotation. Thus it is irrelevant to the coercivity. These results are different from the situation of the inhomogeneously distributed quenched-in stress enlarging the coercivity in Fe-based amorphous alloys. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic ceramics with the composition of 0.7Bi 1- x Pr x Fe 0.96 Mn 0.04 O 3 -0.3BaTiO 3 (BPFM-BT) were successfully fabricated by the traditional solid-state reaction method. In this work, an appropriate amount of Pr has been introduced in the Bi3+ site of the ceramic, which has resulted in a significant enhancement in ferroelectric (P r = 12.18 μC/cm2), piezoelectric properties (d 33 = 116 pC/N), along with narrow bandgap (<1.87 eV), and improved photostriction performance (6.43 × 10−12 m3W−1). In the present work, by optimizing the thickness of the sample perpendicular to the incident light, both the photo-induced strain and the light response speed are improved, while an applied external magnetic field has been found to reduce the photostrictive performance of the multiferroic ceramics. The significant redshift of the Raman mode related to the distortion of the internal BO 6 octahedron under various laser power indicates the expansion of the crystal lattice. The obtained results show that multiferroic BPFM-BT ceramics have great potential in the multifunctionality application of wireless photosensitive sensors. [ABSTRACT FROM AUTHOR]

• Crystallization kinetics of FeNiPC(Nb) amorphous alloys was investigated. • Both thermal stability and activation energy increase after addition 1% Nb. • The magnitude of local Avrami exponent is altered with Nb addition. • The growth rate of primary crystallized phase is restrained with Nb addition. The effects of minor Nb addition on the crystallization mechanism for a FeNiPC(Nb) amorphous alloy were studied via investigating its non-isothermal crystallization kinetics. With minor Nb addition, the thermal stability of the alloy increases as evidenced by the enlargement of the supercooled liquid region. Meanwhile, the location activation energy of both Nb-added and without Nb-added alloys correlates positively with the crystallized volume fraction during the whole primary crystallization stages, as calculated by the isoconversional methods. However, the kinetics analysis using the modified Johnson-Mehl-Avrami-Kolmogorov equation indicates that the addition of Nb changes the crystallization mode of the alloys, that is, from the growth with a decrease nucleation rate to a constant nucleation rate in a diffusion-controlled manner. This can be further confirmed by the atomic force microscopy showing that Nb would restrain the atomic diffusivity and suppress the crystallization growth rate in this alloy. [ABSTRACT FROM AUTHOR]

Examines the characteristics of KTiOAsO4 (KTA) crystals from tungstate fluxes. Analysis of the anomalous scattering and ferroelectric domain of KTA; Mechanism of domain inversion via two-fold-axis in terms of the structural characteristics of KTA; Use of etching and multiple-crystal x-ray topography to investigate the domain-inverted grating of KTA.

Examines the contrast reversal of antiparallel domains in copper-doped crystals. Use of synchrotron topography; Presence of ferroelectric x-ray anomalous-scattering effect at the wavelength; Polarity of the domain walls; Formation of domain walls to compensate the charges from the inhomogeneous distributions of metal atoms in the bulk crystals.

Examines the ferroelastic phase transition in erbium-doped lanthanum pentaphosphate crystals with synchrotron radiation. Characteristics of a classical second-order transition on topographs; Fluctuations of the domain wall numbers with temperature; Link of the domain wall fluctuation with order parameter critical function.

Investigates synchrotron topography used in the characterization of Fe-doped flux-grown KTN with composition on the margin of paraelectric phase. Appearance of growth bands in flux-grown KTN; Impact of the occurrence of the partial transition on the interior of KTN crystals; Analysis on the occurrence and growth characteristics of KTN.

Abstract Fe-based amorphous alloys with excellent soft magnetic properties always suffer catastrophic annealing embrittlement. The soft magnetic and mechanical properties of a series of Fe 84.3- x Co x Si 2 B 13 Cu 0.7 (x = 0, 2, 4, 6, 8) amorphous alloy ribbons were investigated. With appropriate substitution of Co for Fe, the B S of the alloys shows a slight increase and the H C remains at a low level. From two-point bending tests, a sharp transition from ductility to brittleness can be observed upon annealing. The embrittlement can be attributed to localized shear bands due to shear bands branching during deformation. It is found that the ductile-brittle transition temperature increases slightly by applying cryogenic thermal cycling treatment to annealed ribbons, indicating that the annealing embrittlement can be improved to some extent by cryogenic thermal cycling treatment. According to nanoindentation results, the increased shear transformation zone volume is responsible for the bending ductility increment. Ultimately, a ductile Fe 80.3 Co 4 Si 2 B 13 Cu 0.7 amorphous alloy ribbons with a B S of 1.68 T and a H C of 4.8 A/m were obtained by cryogenic thermal cycling treatment after annealing. Highlights • With appropriate substitution of Co for Fe, the B S shows a slight increase, and the H C remains at a low level. • The bending ductility of the annealed ribbons is recovered to some extent by cryogenic thermal cycling. • The increased shear transformation zone volume is responsible for the bending ductility increment. [ABSTRACT FROM AUTHOR]

Abstract Crystallization is a uniform behavior for amorphous alloys while it can be fairly complex. For Fe-B-C alloys with high Fe content, the precipitation of α-Fe is ahead of the Fe-metalloid compounds with temperature increasing. It is found that the crystallization products of Fe-B-C amorphous alloys with Fe content lower than 82% can be modulated by appropriate annealing. The Fe 82 B 12 C 6 alloy is eutectoidally crystallized with the simultaneous precipitation of α-Fe and Fe-metalloid compounds under conventional annealing. It is a diffusion controlled three-dimensionally growth with a constant nucleation rate. However, only α-Fe nanocrystals with a low volume fraction form under rapid annealing, which is evidenced by the results of X-ray and electron diffractions along with the magnetometry. The transmission electron microscopy bright-field images show that the α-Fe nanocrystals obtained by rapid annealing have two different morphologies. One is dendritic with a large characteristic length and the other is equiaxed-like. Highlights • Single α-Fe phase is obtained under suitable rapid annealing for Fe 82 B 12 C 6 alloy. • The α-Fe nanocrystals obtained by rapid annealing have two different morphologies. • The coercivity is drastically reduced due to the absence of hard magnetic phase. [ABSTRACT FROM AUTHOR]

Dielectric capacitors have attracted considerable attention owing to their excellent performance, including high charge-discharge rate as well as good temperature stability and fatigue resistance. Na 0.5 Bi 0.5 TiO 3 (NBT)-based ceramics are considered to be one of the most prospective lead-free dielectric materials because of their unique phase transition and relaxation characteristics. However, the energy storage performance obtained in the currently available materials is not satisfactory. We propose a synergetic optimization strategy through composition design and domain engineering in 0.74Na 0.5 Bi 0.5 TiO 3 -0.26Sr 0.7 Bi 0.2 TiO 3 (NBSBT) ceramic, i.e., by simultaneously refining the grain size and widening the bandgap width, which facilitates a large breakdown strength and Δ P (P m – P r). A high dielectric constant and low remnant polarization is beneficial for obtaining improved energy storage properties. Piezoelectric force microscopy revealed that the introduction of NaNbO 3 (NN) disrupts the microdomains of the NBSBT ceramics and promotes the generation of polar nano-regions. An excellent energy storage density (W rec) of 4.83 J/cm3 and a moderate efficiency (η) of 87.4% are obtained at the optimum composition of 0.85NBSBT-0.15NN. These characteristics demonstrate that (1- x)NBSBT- x NN based ceramics are promising candidate materials for high-temperature energy storage devices and provide an effective strategy for the design of next-generation dielectric capacitors. [ABSTRACT FROM AUTHOR]

Dielectric capacitors with superior power density and ultra-fast charge/discharge capability have attracted growing attention in the pulse power field. In this work, rare earth oxide (Sm 2 O 3) was introduced into (0.74Na 0.5 Bi 0.5 -0.26Sr)Ti 0.9 Zr 0.1 O 3 matrix, to enhance the comprehensive energy storage performance. The structure, dielectric and ferroelectric characteristics of these materials were systematically studied, to assess the potential application in multilayer ceramic capacitors. All samples yielded a perovskite structure, as the addition of Sm 2 O 3 results in a substantial increase in density, along with the enhancement of relaxor behavior and local nanodomains. With increasing Sm 2 O 3 concentration, a distinctly slim ferroelectric hysteresis loop as well as frequency dispersive dielectric characteristics have been detected. The NBSZT-0.02Sm ceramic has realized an excellent energy storage density of 4.62 J/cm3, with a moderately good energy efficiency of 84.38% and favorable temperature stability over a broad temperature range of 102.7–397.1 °C. The activation energy (E a) of the ceramics increased from 1.40 eV to 1.72 eV with Sm 2 O 3 concentration increasing from x = 0 to x = 0.04, which inhibits the appearance of the local electrical branch and thus improves the breakdown strength of the NBSZT- x Sm ceramics. This study provides a novel possibility for designing lead-free ceramic materials for high-temperature capacitors. [ABSTRACT FROM AUTHOR]

• The nanoscale structural heterogeneity was analyzed by small-angle X-ray scattering and atomic force microscopy. • The microalloying of Co and Ni exhibits an opposite effect on the nanoscale structural heterogeneity. • The variation of mechanical behavior further proves the evolution of the nanoscale structural heterogeneity with Co and Ni substitution. • The evolution of magnetic properties induced by microalloying can be attributed to the variation of nanoscale structural heterogeneity. Nanoscale structural heterogeneity is a critical parameter for understanding the structure-property relationships in amorphous alloys. Herein, the small-angle X-ray scattering and atomic force microscopy were utilized to quantitatively investigate the nanoscale structural heterogeneity of the Fe 80- x M x Si 9 B 11 (M = Co and Ni; x = 0, 2, 4) amorphous alloys. The results show that the nanoscale structural heterogeneity of the amorphous alloys increases prominently with Ni substitution, but gradually decreases with the increase of Co content. Such evolution of structural heterogeneity was further verified by the changes in mechanical behavior. The microalloying of Ni can increase the plastic deformation ability and reduce the microhardness, whereas an opposite effect is found in the Co-doped alloys. Finally, Mössbauer spectroscopy reveals an enhancement in ferromagnetic exchange interaction and magnetic anisotropy with Co substitution, while the microalloying of Ni leads to a deteriorative result. Such variations in magnetic properties can be attributed to the evolution of nanoscale structural heterogeneity with Co and Ni additions. Our observation serves as a link between the nanoscale structural heterogeneity and magnetic properties, providing a new sight into understanding the structural origin of the changes in magnetic properties of Fe-based amorphous alloys. [ABSTRACT FROM AUTHOR]

Abstract: The effects of pulse current on the deformation behavior, dislocation structure, microstructural evolution and cavity morphology of the coarse-grained (25μm) AZ31 magnesium alloy during gas bulging process were investigated. The tests of pulse current auxiliary bulging (PCAB) showed that the formability of the alloy was improved as the increase in the peak current density. The results of TEM and SEM analysis showed that the dislocation motion was mainly glide, and the dislocation lines were approximate parallel with few dislocation tangles observed. Moreover, a part of cavity tips turned into circular bead by the concentration of the pulse current, and the rounding effect would lead to the relaxing of the high stress concentrated near the cavity tips. These phenomena indicated that the pulse current not only increased the dislocation motion but also restrained the cavity growing during PCAB process. In addition, the asymmetrical contours of the free bulging samples were observed and their forming mechanism was analyzed. [Copyright &y& Elsevier]

Fe-based metallic glasses are known to have excellent soft magnetic properties, but restricted to the disastrous annealing embrittlement. A novel class of Fe 84- x B 14+ x Zr 2 (x = 0, 3, 6) metallic glasses with extraordinary annealing bending ductility and excellent soft magnetic properties were developed. The metallic glasses exhibit a high B S of 1.54–1.64 T and a low H C of 4.1–5.8 A/m. It is noteworthy that the Fe 84 B 14 Zr 2 metallic glass exhibits the highest ductile to brittle transition temperature among all Fe-based metallic glasses reported to date and the ductile to brittle transition temperature decreases with the decrease of Fe content. Moreover, the well-distributed shear bands can still be formed during bending for Fe 84 B 14 Zr 2 metallic glass after 680 K annealing. Pronounced β-relaxation peak has been observed for Fe 84 B 14 Zr 2 metallic glass in its relaxation spectra. We demonstrate that the bending deformation ability is closely correlated to the β-relaxation. The underlying mechanism for the extraordinary bending deformation ability of Fe 84 B 14 Zr 2 metallic glass after annealing can be attributed to the heterogeneous structure with plenty of loosely packed zones as revealed by the pronounced β-relaxation and high resolution transmission electron microscopy. • Fe 84 B 14 Zr 2 MG with good soft magnetic properties exhibits extraordinarily high DBT temperature. • Fe 84 B 14 Zr 2 MG shows pronounced β-relaxation, relating to plenty of loosely packed zones. • The β-relaxation is regarded as an indication for the bending ability of metallic glasses after annealing. [ABSTRACT FROM AUTHOR]

The disastrous annealing embrittlement of Fe-based metallic glasses with excellent soft magnetic properties is a long-standing issue. In order to alleviate the annealing embrittlement without worsening the soft magnetic properties, ferromagnetic elements Co and Ni are introduced to the Fe 84 Si 2 B 13 P 1 metallic glasses. The microstructure, mechanical and magnetic properties are investigated by synchrotron diffraction, two-point bending test and magnetometry. It is found that, in contrast to Co, proper Ni substitution for Fe significantly optimizes the H c of Fe 84 Si 2 B 13 P 1 metallic glasses and keeps the B s at a high level. According to bending tests, the ductile-brittle transition temperature of the metallic glasses increases slightly with Ni substitution and decreases prominently with Co substitution. Ultimately, the ductile Fe 82 Ni 2 Si 2 B 13 P 1 metallic glasses with B s of 1.65 T and H c of 3.4 A/m have been successfully obtained. Macroscopically, the cheerful propensity to form well-distributed shear bands during bending of Ni-substituted annealed alloys contributes to their good ductility. Furthermore, the alteration of ductile-brittle transition temperature can be conducted by the structural change at the medium-range scale as revealed by the pair distribution function measurements. After annealing the compression at atomic scale ranging from 6 Å to 16 Å of Co-substituted metallic glasses may hinder the creation of well-distributed shear bands and give rise to the deterioration of bending ductility. This work provides a perspective to understand the ductile-brittle transition of metallic glasses from the atomic scale. • With proper substitution of Ni for Fe, H c of Fe 84 Si 2 B 13 P 1 alloys decreases and B s keeps at a high level. • The bending ductility of annealed ribbons improves by Ni substitution. • The Ni-substituted alloys show good propensity to form well-distributed shear bands during bending. • Medium-range structure compression of Fe 78 Co 6 Si 2 B 13 P 1 alloy results in its ductility deterioration. [ABSTRACT FROM AUTHOR]

Examines the fabrication of quasiperiodic tantalum/aluminum multilayer films by magnetron sputtering. Structure characterization of the multilayered films; Use of x-ray diffraction technique; Application of Fibonacci films as optical elements.

Diffusion behavior of carbon and its hardening effect on plasma carburized M50NiL steel were investigated systematically. The plasma carburizing was carried out in a mixture of gaseous acetone (30%) and hydrogen (70%) at temperatures of 400, 450, 500 and 550 °C for durations of 4, 8 and 12 h, respectively. Influences of treatment temperature and duration on properties of the carburized layer were investigated with optical microscope, atomic force microscope, X-ray diffractometer, micro- and nano-indenters, and pin-on-disc tribometer. Results of the tests indicate that cementite is the main phase in the surface layer of specimens carburized at 400 and 450 °C, while that in those carburized at 500 and 550 °C is mainly the carbon expanded martensite. The specimens with cementite in the surface layer show lower surface roughness, higher surface hardness and thus lower wear rate. The diffusion behavior of carbon and resultant microstructure evolution mechanism were studied, indicating that plasma carburizing is a diffusion-controlled process. Activation energies of carbon diffusion into martensite and cementite were calculated, which are 64.5 kJ·mol − 1 and 120.7 kJ·mol − 1 , respectively. The information on the activation energies provides basic data for tuning and predicting the surface properties of plasma carburized M50NiL steel. [ABSTRACT FROM AUTHOR]

Annealing temperature dependent microstructure, optical and electrical properties of sol-gel-deposited HfGdO high-k gate dielectric thin films on Si substrates are systematically investigated. X-ray spectroscopy (XPS) analyses have confirmed that the interfacial layer at HfGdO/Si interface is mainly silicate and the component increases with increasing the annealing temperature. Moreover, the band offsets for HfGdO/Si gate stack as a function of annealing temperature also have been determined. As a result, it can be noted that increase in valence band offset (Δ E v ) and reduction in conduction band offset (Δ E c ) have been detected. Electrical characterizations have indicated that higher annealing temperature effectively improves the electrical characteristics, such as the increased effective permittivity ( k ) and the decreased flat band voltage shift (Δ V fb ). However, due to the reduced Δ E c and the appearance of crystallization, increased leakage current density has been observed with the increase in annealing temperature. [ABSTRACT FROM AUTHOR]

Metallic glasses are structurally heterogeneous on the atomic and nano scales. However, few investigations have been conducted on how the structural heterogeneities in these two scales co-evolve during annealing. In this work, the atomic and nanoscale structural heterogeneity evolution accompanying the magnetic softness is systematically discussed based on the literature and our previous synchrotron X-ray diffraction and atomic force microscopy results. We revealed the co-evolution mechanism of structural heterogeneities on the atomic and nano scales during annealing via the insight of percolation theory from the point of view of the local five-fold symmetry of the clusters. The results indicate that the reduction of atomic-scale structural heterogeneity during annealing is accompanied by an increase in the degree of local five-fold symmetry of the clusters and an alteration in their connection patterns. As the local five-fold symmetry of clusters in Fe-based metallic glasses reaches the percolation threshold, the nanoscale liquid-like regions tend to transform into solid-like regions. The great degree of percolation causes the pronounced weakening of the nanoscale structural heterogeneity accompanying changes in the shape and number of the liquid-like regions. The reduction of the number of liquid-like regions causes a reduction in vertical anisotropy and magnetic softening due to a more uniform and less free volume within the sub-circular shaped liquid-like region. • The evolution of the atomic/nano scale structural heterogeneity and its relation to the magnetic softness was discussed • The co-evolution mechanism of structural heterogeneities on the atomic and nano scales during relaxation is revealed. • The shape of liquid-like regions tend to become nearly circular during relaxation contributing to magnetic softening. [ABSTRACT FROM AUTHOR]

Effects of nitrogen incorporation on the interface chemical bonding states, band alignment and electrical properties of sputtering-derived HfTiO high-k gate stacks on Ge substrates pretreated by trimethylaluminum (TMA) precursor have been investigated by X-ray photoemission spectroscopy (XPS), UV–vis transmission spectroscopy, and electrical measurements. XPS results indicate that incorporation of a moderate amount of nitrogen (3 sccm) incorporation can effectively suppress the formation of unstable GeO 2 and low-k germinate at the interfacial region. Meanwhile, reduction in band gap and valence band offset and increase in conduction band offset have been observed after nitrogen incorporation. Electrical properties were evaluated by capacitance-voltage ( C–V ) and leakage current density-voltage ( J–V ) measurements based on MOS capacitors. Small gate leakage current (4.13 × 10 −7 A/cm 2 at V g = 1 V), almost disappeared hysteresis, and large dielectric constant (19.6) that have been observed for MOS capacitor with HfTiON/Ge stacked gate dielectric with N 2 flow of 3 sccm. [ABSTRACT FROM AUTHOR]

In this work, the band gap, interfacial properties and electrical properties of Gd doped ZrO 2 high-k gate dielectric films deposited by solution method have been systematically investigated. Results have shown that Gd doping can increase band gap energy from 5.65 to 5.92 eV and effectively restrain the formation of low-k SiO x interfacial layer between dielectric and Si substrate. Moreover, the conduction band offset is increased from 2.57 to 3.06 eV by Gd doping, which effectively reduces the leakage current density to 1.8 × 10 −6 A/cm 2 . [ABSTRACT FROM AUTHOR]

HfAlO/Ge gate stack with Al 2 O 3 passivation layer and different Al 2 O 3 concentration in HfAlO layer has been deposited on Ge substrate by atomic layer deposition. Based on measurements from capacitance-voltage and current density-voltage curves, the evolution of the electrical properties of Ge-based MOS capacitors based on HfAlO/Al 2 O 3 /Ge gate stack has been determined as functions of precursor ratio and annealing temperature. It has been found that high annealing temperature and high Al 2 O 3 incorporation in HfAlO films can obtain improved electrical properties such as low hysteresis, low flat-band, low flat-band shift and low interface-state density. However, the oxide-charge density obviously increases with rising the annealing temperature and decreasing Al 2 O 3 incorporation in HfAlO film. By analysis and calculation, it can be noted that the samples annealed at 500 °C holds the lowest leakage current density and the change of the precursor ratio has no apparent effect in 500 °C-annealed Ge MOS capacitor. To investigate current conduction mechanism of Ge MOS capacitors employing HfAlO/Al 2 O 3 gate stacks, current density-voltage measurements have been carried out as functions of annealing temperature and precursor ratio. The involved leakage current conduction mechanisms of the as-deposited and 500 °C-annealed HfAlO/Al 2 O 3 /Ge MOS capacitors for substrate injection also have been discussed in detail. [ABSTRACT FROM AUTHOR]

Deposition of HfAlO x gate dielectric films on n-type Si and quartz substrates by sol-gel technique has been performed and the optical, electrical characteristics of the as-deposited HfAlO x thin films as a function of annealing temperature have been investigated. The optical properties of HfAlO x thin films related to annealing temperature are investigated by ultraviolet-visible spectroscopy (UV–vis) and spectroscopy ellipsometry (SE). By measurement of UV–vis, average transmission of all the HfAlO x samples are about 85% owing to their uniform composition. And the increase in band gap has been observed with the increase of annealing temperature. Moreover, the increase of refractive index (n) and density with the increase of annealing temperature are obtained by SE measurements. Additionally, the electrical properties based on Al/Si/HfAlO x /Al capacitor are analyzed by means of the high frequency capacitance-voltage ( C-V ) and the leakage current density-voltage ( J-V ) characteristics. Results have shown that 400 °C-annealed sample demonstrates good electrical performance, including larger dielectric constant of 12.93 and lower leakage current density of 3.75×10 −7 A/cm 2 at the gate voltage of 1 V. Additionally, the leakage current conduction mechanisms as functions of annealing temperatures are also discussed systematically. [ABSTRACT FROM AUTHOR]

In this letter, annealing temperature dependence on the structure, band gap energy and electrical properties of TiO 2 doped ZrO 2 gate dielectrics deposited by sol-gel method at low temperature were systemically investigated. The crystalline temperature of TiO 2 doped ZrO 2 is up to 600 °C. The transmittance and band gap value of the ZrTiO x film were about 75% and 4.0 eV, respectively. 300 °C-annealed ZrTiO x MOS capacitor with high dielectric constant of 34.9, a small hysteresis value of 0.004 and low leakage current density of 2.7 × 10 −4 A/cm 2 were obtained. The dominant conduction mechanisms of Al/ZrTiO 4 / n -Si MOS structures were schottky emission and ohmic conduction in the low electric field and direct tunneling in the high electric field. As a result, it can be concluded that sol-gel derived ZrTiO x gate dielectric displays potential application as is a promising candidate in future MOS electronic devices. [ABSTRACT FROM AUTHOR]

High- k HfO x N y and HfO 2 have been applied to amorphous InGaZnO ( a -IGZO) metal–oxide–semiconductor (MOS) capacitors as high-k gate dielectrics by using radio-frequency sputtering at room temperature. Effects of nitrogen incorporation on the optical band gap, band alignment and electrical properties of HfO x N y /IGZO/Si gate stacks have been systematically investigated by spectroscopic ellipsometry (SE), UV–vis spectroscopy, x-ray photoemission spectroscopy (XPS) and electrical measurements. Experimental results have confirmed the successful incorporation of nitrogen into HfO 2 films and reduction in band gap with the incorporation of nitrogen for HfO x N y thin films. Reduction in valence band offset and increase in conduction band offset have been observed for HfO x N y /IGZO gate stack. Electrical properties measurements for a -IGZO MOS capacitors based on HfO x N y gate dielectrics have indicated that nitrogen incorporation leads to the improved interface quality, increased dielectric constant, reduced hysteresis voltage, and decreased leakage current density. Meanwhile, the leakage current mechanism under gate injection for MOS capacitors based on HfO 2 and HfO x N y high-k gate dielectrics has been investigated systematically. [ABSTRACT FROM AUTHOR]

A large tensile plastic deformation was achieved in ZrCu-based metallic glass composites with a metastable B2 phase. It was found that the B2 phase can effectively promote the density of the stress concentration sites and enhance the formation and interaction of multiple shear bands, which significantly stabilize the tensile plastic deformation of metallic glass composites. Based on the concept of the normalized strain-hardening rate, the critical volume fraction for the stable tensile plastic deformation of metallic glass composites was determined. [ABSTRACT FROM AUTHOR]

• The relaxation-induced evolution of nanoscale structural heterogeneity is analyzed by atomic force microscopy in Fe 80 Si 9 B 11 metallic glass. • The degeneration of nanoscale structural heterogeneity induces the improvement of soft magnetic properties. • The soft magnetic properties can be optimized by selectively tailoring the intrinsic structural heterogeneity of Fe-based metallic glass. Despite the mesoscopic isotropic nature of metallic glasses, there is a certain degree of structural heterogeneity down to the nanoscale. However, how structural heterogeneity affects the magnetic properties is still unclear. In this work, the relaxation-induced structural heterogeneity and magnetic properties evolution of Fe 80 Si 9 B 11 metallic glass were investigated by atomic force microscopy (AFM) and Mössbauer spectroscopy. We revealed that the correlation-length of nanoscale heterogeneity relates closely with the ferromagnetic exchange interaction together with the magnetic anisotropy, providing experimental evidence of the intrinsic link between the nanoscale structural heterogeneity and magnetic properties for Fe-based metallic glasses. The degeneration of nanoscale structural heterogeneity induces the enhancement of the ferromagnetic exchange interaction and weakening of the magnetic anisotropy. Our results have a vital significance in understanding the structure-property relationship of metallic glass. [ABSTRACT FROM AUTHOR]

Abstract: IIIV x N1−x ternary alloys are promising materials for their applications in light-emitting devices in the range of wavelength from ultra violet to the infrared ray due to the large bowing of band gap energy. In this paper, molecular dynamical method was used to calculate the solubility of phosphorus in GaN by using the Gibbs free energy and the dielectric theory. The calculation results show that the content of P in GaN varies with the growth temperature, which may be larger than 25% in the N-rich GaP x N1−x or less than 90% in the P-rich GaP x N1−x , at the growth temperature of about 1500K. We compared our theoretical results with those reported in references. By using light-radiation heating together with low-pressure metal-organic chemical vapor deposition, and ion implantation techniques, we have successfully synthesized N-rich (x &#60;0.17) and P-rich GaP x N1−x (x >0.90) compounds. [Copyright &y& Elsevier]

Abstract: Cations of Y and Sr co-substituting for La and Ca at A site in La2/3Ca1/3MnO3 compound, La2/3−x Y x Ca1/3−y Sr y MnO3, were synthesized successfully by solid-state reaction. X-ray diffraction shows there is only one phase with the dopants of Y and Sr within x ≤0.20 or y ≤0.19. The lattice parameters along a-, b-, and c-direction remain almost unchanged with x ≤0.20. The bond angle of Mnh name="sbnd" />Mn increases from 151.9° for x =0 to 172.7° for x =0.20 monotonically, which indicates that the Jahn–Teller effect in MnO6 octahedron decreases with increasing x. The temperature dependence of resistance with/without magnetic applied were measured and fitted theoretically. The metal-to-insulator transition temperature, T MI, decreases with increasing the Y content with x ≤0.10 while T MI increases slightly with further increasing x. The Y-content dependence of magnetoresistance shows a parabolic behavior. The maximum MR value corresponds to x =0.08–0.10. We attributed these variations in the structure and transportation to the cation disorder due to the cation doping. [Copyright &y& Elsevier]

Abstract: Modulation-doped Al0.22Ga0.78N/GaN heterostructure with 1000Å Si-doped n-Al0.22Ga0.78N barrier (n-AlGaN) were deposited on (0001)-oriented sapphire (α-Al2O3) by means of atmosphere-pressure metal-organic chemical vapor deposition. The reciprocal space mappings of symmetric reflection (0002) and asymmetric reflection (10 4) were measured with high resolution X-ray diffraction. The results indicate that the microstructure and strain status of barrier correlate to that of the underlying i-GaN layer. The barrier holds an “abnormal” strain-relaxation status, which probably results from the internal defects of n-AlGaN and the strain relaxation status at the i-GaN/α-Al2O3 interfaces. The results from grazing incidence X-ray diffraction show that the strain in barrier is nonuniform, which is consistent with the results from the reciprocal space mappings. [Copyright &y& Elsevier]

Abstract: La0.67Ca0.33MnO3 (LCMO)/YBa2Cu3O y (YBCO)/Ni trilayers were fabricated with varying thickness of the mid-superconducting YBCO layer. Two different deposition systems were used to avoid oxidation of the magnetic metal Ni and contamination of the deposition systems. Transport properties show that the temperature dependence of resistance goes from a metallic-to-metal–insulator transition (manganite-like behavior) to a superconducting behavior (M–M–S) with increase of the thickness of the YBCO layer. The magnetoresistance (MR) ratio is very small in comparison with LCMO/YBCO bilayers at low temperature. Such phenomenon may depend on the charge transfer and the magnetic spin interaction between the bottom and cap magnetic layers. [Copyright &y& Elsevier]

Abstract: Gd-doped poly-crystallized YBa2Cu3−xGdxO7−δ compounds with x=0–0.15 were synthesized using the solid-state reaction technique. We found that Gd3+ ions prefer to replace Cu at Cu(2) sites (CuO2 planar) within x<0.05, which may due to the ion size effect, and Gd3+ ions then begin to partially occupy Cu(1) sites (CuO chain) with increasing the doping content, which gives vital influence on superconductivity and spin-gap properties. There is no clear role on spin gap opening temperature played by magnetic element doping. [Copyright &y& Elsevier]

We have synthesized the La doped YBa2−xLaxCu3Oy ceramic cuprates with x&les;0.30 by the solid state reaction technique under the quenching temperature from 350 to 650 °C. X-ray diffraction and scanning electron microscopy studies indicate that all the synthesized samples contain one single phase. La is replacing for Ba at Ba-site in YBa2Cu3Oy. The unit cell volume varies with La content and with the quenching temperature. The thermal expansion for the unit cell volume at different quenching temperature is discussed. For the full oxidation samples the zero resistance temperature, Tc0, is almost unchanged with x&les;0.20 whilst Tc0 decreases with the increase of La content for the quenched samples. The spin gap opening temperature, Ts, for all the quenched and annealing samples are determined from the temperature dependence of resistance. [Copyright &y& Elsevier]

Polycrystallized Y1−xCaxBa1.9Nd0.1Cu3Oy (YCBNCO) compounds with x&les;0.40 were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X-ray diffraction with Rietveld refinements. The transport properties for YCBNCO were measured by the standard four-probe method in the temperature range from 20 to 300 K. With the increase of Ca content, the variation of the superconducting transition temperature Tc can be divided into three regions: in the doping region I with x&les;0.10, Tc decreases sharply and linearly with x, which may relate to the competition between Ca2+ and Nd3+; in the region II with 0.10, Tc deviates the fitting line; and in region III with x&ges;0.25, Tc decreases slowly with increasing Ca content,which may relate to the formation of the Ca-rich phase. The dependence of resistivity on temperature, and the relation of the structural parameters versus the content of Ca were discussed. The Ca content dependence of the spin-gap opening temperatures in the normal state for YCBNCO was investigated. [Copyright &y& Elsevier]

High purity KTiOPO4 (KTP) crystals have been grown using a flux method. The quality, SHG efficiency and damage threshold of KTP crystals grown from high purity reagents were compared with those grown from commercial reagents. Experimental results indicate that KTP crystals using a high purity charge contain less impurities and possess higher SHG efficiency and damage threshold than do crystals grown from commercial reagents. It is proposed that decreasing the concentrations of impurities is an effective way of raising the damage threshold for KTP crystals. [Copyright &y& Elsevier]

The La2/3Ca1/3MnO3 (LCMO, tm=300 A˚)/YBa2Cu3O7−δ (YBCO, ts=20–500 A˚) heterostructural bilayers are prepared by the rf magnetic sputtering technique on SrTiO3 (STO) substrate at high temperature. Using the four-probe method, the electronic and magnetic transport properties have been investigated with and without magnetic field applied up to 4 T, The superconducting zero resistance temperature increases with the increase of the thickness of YBCO, ts, with ts>85 A˚. The nature of resistance for LCMO is screened by YBCO with the thickness more than about 250 A˚, but the magnetoresistance (MR) effect is observed in the bilayers. MR increases with the decrease of the thickness of YBCO. Structural characterizations of the bilayers show that there is interdiffusion appeared in the interface between LCMO and YBCO, and, LCMO and STO. [Copyright &y& Elsevier]