Structure Of Amorphous Phase Research Articles

The influence of layer thickness and post annealing on magnetism of pulsed laser deposited ZnO/Co multilayers

ZnO/Co multilayers with different layers have been deposited on silicate (100) substrate by the pulsed laser deposition method. The as-deposited multilayers present the structure of amorphous phase and a narrow hysteresis loop with high saturation magnetization and low coercivity, showing the typical soft magnetic behavior. The post annealing at the elevated temperature causes the transformation from as-deposited amorphous phase to crystalline metallic cobalt and ZnO phase, as well as the interdiffusion of different layer forming CoO and ZnCo2O4 phases. The presence of crystalline metallic cobalt phase with ferromagnetic (FM) and cobalt oxide (CoO) phase with antiferromagnetic (AFM) is beneficial to the FM–AFM coupling, resulting in the shift of widening of the hysteresis loop. But an excessively high annealing temperatures leads to the formation of large amount of simple or complex oxides with paramagnetic, antiferromagnetic properties, inducing the decrease of magnetic properties significantly.

Structure and mechanical properties of multi-element (AlCrMnMoNiZr)Nx coatings by reactive magnetron sputtering

The paper investigates the structure and properties of AlCrMnMoNiZr nitride films prepared by reactive direct current sputtering at various N2-to-Ar flow ratios (RN). The films deposited at low RN show amorphous phase, micro-voids and clusters structure, and hence have low hardness and modulus. As RN increases, the films present face-centered cubic structure (FCC) with (111) preferred orientation, small crystalline sizes, dense structure, smooth surface, and consequently have higher hardness and modulus. When RN=1.0, the nitride film has peak hardness and modulus of 11.9GPa and 202GPa, and the highest value of H/E and H3/E2. Compared with the metallic film its tribological properties are relatively worse. This can be ascribed to the difference in film thickness. According to the observations of the typical surface morphologies, the dominant wear mechanism of the AlCrMnMoNiZr nitride films is adhesive wear.

Corrosion Resistance in Sodium Chloride Solution of Ni-Co-P Electro-Brush Amorphous Coatings to Replace Hard Chromium Coatings

Abstract To remanufacture damaged hard chromium plating devices, Ni-Co-P alloy brush coating is developed by electro brush plating technique. Surface morphology, element composition and phase structure are separately investigated by Scanning Electron Microscopy, Energy Spectrometer and X-ray Diffraction. The results show that Ni-Co-P alloy coating gets typical ‘packet shape’ morphology and amorphous phase structure, with 9.9wt% P element. The corrosion resistance of Ni-Co-P alloy coating is also studied by electrochemical experiments and immersion tests. The results show that its corrosion resistance is superior to that of hard chromium plating, can be applied to the remanufacture of damaged hard chromium plating equipment.

Structures of crystalline and amorphous phases of the poly(ethylene oxide)/lithium trifluoromethanesulfonate complexes as studied by solid-state high-resolution 13C nuclear magnetic resonance

Solid-state high-resolution 13C NMR studies are carried out on a series of PEO/LiCF3SO3 complexes with different EO/Li molar ratios at room temperature. The obtained spectra clearly show that there are four phases, namely the crystalline PEO, the amorphous PEO, the PEO3:LiCF3SO3 crystalline complex and the PEO3:LiCF3SO3 amorphous complex, coexisting in the samples with EO/Li molar ratios larger than 3. The solid-state 13C NMR spectrum of the PEO3:LiCF3SO3 crystalline complex exhibits six peaks with high resolution at room temperature, while the previously reported 13C NMR spectra showed only one peak. These six peaks are assigned with the combination of the 13C dipolar-INADEQUATE and the two-dimensional exchange spectra. Moreover, remarkable helical jumps of PEO segments are demonstrated to exist in the crystalline complex. Our study paves the way towards a better understanding of the phase structures and subsequently the conduction mechanism of PEO-based solid polymer electrolytes.

Impact of Melt Spinning on Electrochemical Hydrogen Storage Characteristics of Mg<sub>20</sub>Ni<sub>9</sub>M<sub>1</sub> (M=Cu, Co) Alloys

The melt-spinning technique is used to fabricate the Mg20Ni9M1 (M=Cu, Co) alloys with nanocrystalline and amorphous structure. The microstructures of the as-spun alloys were characterized by XRD and TEM. The electrochemical hydrogen storage properties of the alloys were measured. The results show that the as-spun (M=Cu) alloys hold an entire nanocrystalline structure and small amount of amorphous phase is visible on the grain boundaries of the as-spun (M=Co) alloy. The discharge capacity and high rate discharge ability (HRD) of the alloys visibly grow with the rising of the spinning rate. The action of the melt spinning on the cycle stability of the alloys is associated with substitution element. For M=Cu, the capacity retaining rate (SN) evidently falls with the growing of the spinning rate; whereas for M=Co, it first declines and then augments.

Characterization of Magnetic Transformation at Curie Temperature in Finemet-type Microwires by DSC

ABSTRACTFinemet-type amorphous alloys are good soft magnetic materials due to their amorphous-nanocrystalline structure with close to zero magnetostriction. A very sensitive method for controlling relaxation and crystallization processes in such alloys is proposed. It consists in precise DSC measurements of heat capacity peak in the vicinity of the Curie temperature TC. Time-temperature dependencies of TC for microwires in comparison with ribbon shaped amorphous alloys were studied. Relaxation of atomic structure of amorphous phase during annealing was accompanied by an increase of TC. σ-shaped time dependencies are characterized by at least two relaxation processes, corresponding apparent values of activation energy were estimated. Decomposition of amorphous phase and redistribution of components between amorphous phase and growing nanocrystals affect the shape and position of the DSC peak at TC as well.Study of microwires with glass coating revealed the influence of internal stress on the shape and position of the Curie peak on DSC curve: increase of internal strain tensions leads to suppression of the TC peak.

The Structural Model of Impact Toughness of Particulate-Filled Polymer Nanocomposites

A quantitative structural model of particulate- filled polymer composites impact toughness, based on the fractal analysis ideas, was offered. The model demonstrated good correspondence with the experimental data. It has been shown that the action of nanofiller as nucleator, resulting in crystallinity degree and amorphous phase structure change, exert the main influence on impact toughness value.

Structure of the dense amorphous carbon phase synthesized in a mixture with diamond as a result of shock compression of carbon black

Soft X-ray emission and absorption spectroscopy methods were used in the present work to study experimentally the electronic structure of the dense amorphous carbon phase synthesized in a mixture with diamond as a result of shock compression of carbon black. The X-ray emission C Kα bands, representing the energy distribution of the C 2p-like states, have been recorded for the amorphous carbon phase and, for comparison, for diamond, lonsdaleite, graphite, and carbon black. For the amorphous carbon phase, diamond and lonsdaleite the spectra of quantum yields of the X-ray photoeffect in the area of the C K absorption edge have been recorded as well. Total and partial densities of states of the carbon H-6 and bct-4 phases, diamond and lonsdaleite have been calculated using the first-principles self-consistent full potential linearized augmented plane wave (FP-LAPW) method. Comparison on a common energy scale of the X-ray emission C Kα bands and C K quantum yields of the dense amorphous carbon phase as well as the theoretical curves of partial C 2p-like states of the carbon H-6 and bct-4 phases reveals that, the electronic structure of the amorphous carbon phase under consideration is well described by that of the carbon bct-4 phase. The experimental X-ray emission and absorption spectroscopy data indicate that the amorphous carbon phase studied is metallic, being in agreement with the results of the theoretical FP-LAPW calculations.

Superconducting property of Zr–Co–Al–Nb metallic glasses

The superconducting property of Zr55Co(30−x)Al15Nbx (x=0–20at.%) metallic glasses fabricated by rapid solidification was investigated. The Zr55Co(30–x)Al15Nbx (x=5–20at.%) metallic glasses with a mixture structure of amorphous and nanocrystal phases exhibited superconductivity of Tc,on=1.8–2.6K. The maximum Tc,on=2.6K was obtained for the Zr55Co10Al15Nb20 metallic glass. This was attributable to the superconducting property of nanocrystalline particles contained in the Zr55Co10Al15Nb20 alloy. The increase of Nb element in the Zr55Co(30–x)Al15Nbx alloy led to the increase of Tc,on and the decrease of glass transition temperature. The glass transition temperature was between 704 and 749K for the Zr55Co(30–x)Al15Nbx (x=0–20at.%) alloys. The temperature interval of supercooled liquid state was between 51 and 68K for the Zr55Co(30–x)Al15Nbx (x=0–20at.%) alloys.

Preparations and Properties of Amorphous/Nanocrystalline Ni-Mo Alloy Coating Obtained by Electrodeposition

The amorphous/nanocrystalline Ni-Mo alloys were deposited in alkaline nickel carbonate solution in this paper. It is found that the molybdenum content in the deposit obtained in carbonate solution is to 21.76 at.% with amorphous and nanocrystalline phase structure. Under the same conditions, the amorphous/nanocrystalline alloys are more accessible to be obtained in carbonate solution as the sulfate solution. And the deposits with a tiny internal stress and tiny granules and well-proportioned grains at the substrate were relatively better and easy to be controlled with a better mechanical performance.

Local structure and site substitution in amorphous and quasicrystalline Zr–Ti–Ni–(Cu) alloys

Local structures of amorphous and quasicrystalline phases in Zr–Ti–Ni and Zr–Ti–Ni–Cu alloys have been studied by means of x-ray absorption spectroscopy. The amorphous phases show a high degree of icosahedral short-range order. In all investigated systems local order around Cu and Ni atoms was found to be nearly identical pointing to site substitution of Ni by Cu as the reason for an improved glass forming ability when Ni is partly substituted by Cu. The results strengthen an icosahedral cluster based approach for the structure of metallic glasses and indicate the importance of the medium-range order on glass formation.

Distinctive features arising in maximally random jammed packings of superballs

Dense random packings of hard particles are useful models of granular media and are closely related to the structure of nonequilibrium low-temperature amorphous phases of matter. Most work has been done for random jammed packings of spheres and it is only recently that corresponding packings of nonspherical particles (e.g., ellipsoids) have received attention. Here we report a study of the maximally random jammed (MRJ) packings of binary superdisks and monodispersed superballs whose shapes are defined by |x1|2p+...+|xd|2p<or=1 with d=2 and 3, respectively, where p is the deformation parameter with values in the interval (0,infinity). As p increases from zero, one can get a family of both concave (0<p<0.5) and convex (p>or=0.5) particles with square symmetry (d=2), or octahedral and cubic symmetry (d=3). In particular, for p=1 the particle is a perfect sphere (circular disk) and for p-->infinity the particle is a perfect cube (square). We find that the MRJ densities of such packings increase dramatically and nonanalytically as one moves away from the circular-disk and sphere point (p=1). Moreover, the disordered packings are hypostatic, i.e., the average number of contacting neighbors is less than twice the total number of degrees of freedom per particle, and yet the packings are mechanically stable. As a result, the local arrangements of particles are necessarily nontrivially correlated to achieve jamming. We term such correlated structures "nongeneric." The degree of "nongenericity" of the packings is quantitatively characterized by determining the fraction of local coordination structures in which the central particles have fewer contacting neighbors than average. We also show that such seemingly "special" packing configurations are counterintuitively not rare. As the anisotropy of the particles increases, the fraction of rattlers decreases while the minimal orientational order as measured by the tetratic and cubatic order parameters increases. These characteristics result from the unique manner in which superballs break their rotational symmetry, which also makes the superdisk and superball packings distinctly different from other known nonspherical hard-particle packings.

Parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation method

The properties of parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation technique were investigated. The configuration of the polymerization chamber was altered from horizontal to vertical and designed with a circular symmetry in the z-direction to improve the deposition rate. The growth rate of the thin films was improved 2-5 times in a vertical configuration compared to a horizontal configuration. Potential factors responsible for such an improvement include the effect of coincidence between the flow direction of the gases and the direction of the convection in the reaction tube due to buoyancy. The synthesized films have a high transparency (>90%) in the visible region, a smooth surface morphology (Rs<5.0 nm), and amorphous phase structures with the presence of some crystalline domains.

The effect of microalloying on mechanical properties in CuZrAl bulk metallic glass

The effect of the minor addition of elements Ta and Fe on the mechanical properties of the CuZrAl BMG was investigated by compression tests. It was found that the addition improves significantly the plasticity at room temperature. The compressive plastic strain enhanced from 0.59% for Cu 46Zr 47Al 7 BMG to 2.62% and 4.81% for Cu 46Zr 45Al 7Ta 2 and Cu 44Zr 47Al 7Fe 2 BMG, respectively. The microstructure of Cu 44Zr 47Al 7Fe 2 BMG was further investigated by TEM, which reveals the occurrence of phase separation with the formation of a Cu-rich phase and a Fe-rich phase due to the minor addition of Fe. The formation of inhomogeneous structure in amorphous phase, which results in the activation of multi shear bands, can account for the improvement of the plasticity of the base BMG. The present results provide a promising approach to enhance the plasticity of BMGs through compositional and structural design by microalloying.

Controllable growth and magnetic characterization of electrodeposited nanocrystalline Ni–P alloy nanotube and nanowire arrays inside AAO template

The highly ordered Ni–P alloy nanotube and nanowire arrays with high aspect-ratio have been successfully synthesized inside porous anodic aluminum oxide (AAO) membranes by self-assembly electrodeposition at different current densities. The as-synthesized Ni–P alloy arrays have the amorphous phase structure with nanograin of crystalline Ni. The length and outer diameter predominantly determined by the deposition time and pore diameter of the AAO membranes achieve 40 μm and 200 nm, respectively. The formation of nanotubes or nanowires during electrodeposition mainly depends on the current densities, deposition time and phosphorous acid concentration in the electroplating bath. The magnetic properties of these nanostructure arrays have also been studied. From the hysteresis loops, it is obtained that the nanotube and nanowire arrays have anisotropy with the easy magnetization along the direction of the arrays. Moreover, as the soft magnetic materials, the nanotube array is better than nanowire array in magnetic performance of saturation magnetization.

Activity and selectivity of CO oxidation in H 2 rich stream over the Ag/Co/Ce mixed oxide catalysts

Silver, cobalt and ceria mixed oxide catalysts were prepared at different metal/metal oxide molar ratios by the co-precipitation method, calcined at different temperatures (200 °C, 450 °C) and tested for the selective CO oxidation reaction in H 2 rich gas stream. XRD, XPS, N 2 physisorption, SEM and TPR-H 2 techniques were used to characterize the catalysts. Catalysts have an average pore diameter in the mesoporous range. Catalysts which were calcined at 200 °C had amorphous phase structure. After calcination at 450 °C, not only the crystal phase structure but also decrease in BET surface areas of the catalysts and the shift at light off temperatures of the catalysts to the higher temperatures were obtained. The highest activity and selectivity was obtained from the catalysts calcined 200 °C which were 50/50 Ag–Co and 50/50 Co–Ce mixed oxide catalysts, respectively, which did not loose their activity and selectivity in a reaction period of 5800 min.

Influence of Radio-Frequecy Power on Structural and Electrical Properties of Sputtered Hafnium Dioxide Thin Films

Hafnium dioxide (HfO2) thin films are prepared by rf magnetron sputtering. The influences of rf power on the structure, chemical states and electrical properties of the thin films were investigated through x-ray diffraction, x-ray photoelectron spectroscopy, capacitance-voltage and leakage current density-voltage measurement and UV-VIS spectrophotometry. The results show that the HfO2 thin films have a mixed structure of amorphous and poly crystalline phases. With increasing rf power, the crystallinity is enhanced and the crystallite size of the thin films is increased. The oxidation of Hf atoms is improved with increasing rf power for the HfO2 thin films. The flat band shift, oxide charge density and leakage current density of the thin films all decrease as the rf power increases from 50 to 110 W, and then increase as the rf power is increased to 140 W. The band gap energy is smaller for the thin film deposited at 110 W.

オゾン酸化処理カーボンブラックの特性分析

Some kinds of surface oxidized carbon black (CB) particles were prepared by ozone treatment system with different reaction time. The morphological damages on CB, for examples, porous or oxidized amorphous phase structure, were generally formed by other oxidation method, such as acid treatment. Such damages on CB surface after ozone oxidation were not generated by STEM observation. The amount of generated functional group by surface oxidation on CB was determined by the vacuum pyrolysis and TG/MS (thermo-gravimetric and mass spectrometry). The amount of CO from -OH groups and CO2 from -COOH groups during vacuum pyrolysis from surface treated CB increased in proportional to ozone oxidation time. Furthermore, NO and SO2 functional groups on ozone oxidized CB surface were discovered by using TG/MS method. The amount of each functional group increased with increase of ozone oxidizing time, it seems that such functional groups were produced by the reaction with during ozone treatment. TG/MS is useful method for detecting the various functional groups of CB.

Electrodeposited Ni–S intermetallic compound film electrodes for hydrogen evolution reaction in alkaline solutions

Tailoring of nickel–sulfur (Ni–S) intermetallic compound film electrodes for hydrogen evolution reaction in alkaline solutions was attempted by electrodeposition from a typical Watts bath containing sodium thiosulfate as sulfur source and sulfosalicylic acid as additive. The XRD analysis shows that the as-deposited Ni–S film electrode with fine morphological features comprised of intermetallic compound phase structure and amorphous phase structure. The intermetallic compound film electrodes generate a higher catalytic activity for the hydrogen evolution reaction in alkaline solution in comparison with Ni–S film electrodes comprised of amorphous phase structures, even with commercial Ni mesh or Ni/RuO 2 composite electrode.

Investigation of Trans Content in Amorphous Phase of stretched Polyethylene Terephthalate by Solid-state High resolution 13C NMR Spectroscopy

Crystalline, constrained noncrystalline, and amorphous phase structures for polyethylene terephthalate (PET) stretched at 75, 80, and 90°C were investigated by solid-state high resolution 13 C NMR. Saturation recovery pulse sequence is a very powerful tool for investigating not only the molecular structure but also the molecular mobility. Spin-lattice relaxation behavior of trans methylene carbon was decomposed by three components, which are assignable to crystalline, constrained noncrystalline, and amorphous phases. The weight content of each component can be estimated by the relaxation behavior. The stretching process induced the transformation from gauche to trans conformation. The trans content with the longest T 1c corresponds to the crystallinity, which was in good agreement with DSC measurement. The trans content in the amorphous phase was also estimated by the ratio between the gauche content assignable to the amorphous phase and the amorphous component of the trans conformer decomposed by relaxation measurement. The trans content of unstretched PET was as low as 21%, whereas that for five-times stretched PET was about 60%.