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Ru underlayer effects on the thermal stability of the magnetic properties in Co-Sm amorphous films have been investigated in terms of its robustness for the thermal-process in the fabrication of GHz band micro-magnetic devices. The anisotropy magnetic field [H.sub.k] of the Co-Sm film was tending to decrease with an increase in the annealing temperature, but the reduction in [H.sub.k] due to thermal-process became small by introducing the Ru underlayer. The high-resolution transmission electron microscopy (HR-TEM) observations revealed the presence of nanosized crystalline Sm segregation at the interface between the Co-Sm film and Si[O.sub.2]/Si substrate in the films without Ru underlayer, while there is no Sm segregation in the film with Ru underlayer. Sm segregation and the subsequent thermally induced phase-separation are one of the factors for the reduction in [H.sub.k]. Ru underlayer effectively prevents the segregation of crystalline Sm and the resulting reduction in [H.sub.k]. High-frequency magnetic property of Co-Sm film with Ru underlayer was superior to that without Ru underlayer for same annealing condition. Index Terms--Anisotropy magnetic field, Co-Sm, permeability, thermal stability, underlayer.

Fe-based amorphous powders with high magnetic flux density were fabricated in an extremely high cooling rate of over [10.sup.6] K/s by spinning water atomization process (SWAP). The composition of the alloys studied were [Fe.sub.79] [([Si.sub.o.5] [B.sub.0.5]).sub.19] [C.sub.2] and [Fe.sub.x] [([Si.sub.0.3] [B.sub.0.7]).sub.98 - x] [C.sub.2] (x = 79, 80, 81, 83, 84). The saturation flux density Bs increased with increasing iron content. For [Fe.sub.83] [([Si.sub.0.3] [B.sub.0.7).sub.15] [C.sub.2], the Bs value was 1.64 T, which is 31% higher than that of our previously developed [([Fe.sub.97] [Cr.sub.0.03]).sub.76] [([Si.sub.0.5] [B.sub.0.5]).sub.22] [C.sub.2] alloy. Furthermore, consolidated cores of amorphous powders were also fabricated by compact-pressing techniques. Index Terms--Amorphous powder, high-saturation flux density, soft-magnetic, water atomization.

Results show that irradiation change in the structure and phase transition properties of the copolymer film is controlled by polarization defect and amorphization phase. Data also indicate that reducing rate of amorphization process improves the electrochemical responses of the copolymer.

The formation of crystalline and amorphous solids is described using a simple glass bead demonstration and a discussion of annealing and rapid quenching on a computer.

A study prepared copper colloids from 99.999% CuO powder in 2-propanol using the laser ablation technique that employed wavelengths of 1064 nm and 532 nm. Detailed investigations of these conspicuously stable copper colloids with large mean sizes found that their production and properties displayed wavelength dependence. The colloids prepared in this experiment provide an opportunity to conveniently and directly probe the surface-enhanced Raman scattering without the influence of ions or stabilizer reagents.

The consequences of gamma-irradiation at 77 K on two crystalline forms of water, namely, cubic and hexagonal ice, and on two amorphous forms of water, made by hyperquenching of liquid water or deposition of water vapors, were investigated by electron spin resonance spectroscopy. Primarily, OH radicals were produced from cubic ice directly made from liquid water. On the other hand, comparable quantities of OH and HO2 radicals were produced on irradiation of cubic ice made by heating glassy water.

An experiment was conducted to determine the efficiency of a nipiin two terminal device based on an amorphous silicon alloy which exhibits features such as good color separation and high dynamic range. The application of a nipiin structure for color detection was affected by a strong intensity dependence of the transient photocurrent response after bias voltage and light switching. A reverse biased diode of a photocurrent diode also showed a compensatory photocurrent activity as observed after the light was on and bias voltage switching was set at a range of +0.6V to 1V.

The spontaneous reaction of C3O2 with HCl on the acid hydrate surface was investigated by Fourier transform infrared spectroscopy at low temperature. The first appearing reaction product at 83 K was assigned to chloroformylketene while the second, observed at 145 K, to malonyl dichloride by comparison with previously reported data in matrix isolation spectroscopy. Findings showed that monohydrate H3O+Cl- is more reactive than higher hydrates because of easier C3O2 protonation.

The friction and wear micromechanisms of amorphous hydrogenated carbon films were investigated experimentally using commercially available thin-film rigid disks with sputtered carbon overcoats and [Al.sub.2][O.sub.3]-TiC magnetic recording heads. Continuous sliding tests demonstrated the existence of two distinct friction and wear regimes characterized by different dominant micromechanisms. Scanning electron microscopy and Raman spectroscopy revealed that the evolution of friction in the first regime is due to changes of the surface microtopography and the film structure from amorphous carbon to polycrystalline graphite. Atomic force microscopy showed that the topography changes result from asperity nanofracture leading to the gradual removal of carbon material and the generation of ultrafine wear debris. The friction behavior in the second regime is due to various wear processes arising on the carbon film surface. High friction promotes surface micropitting and the formation of significantly deeper and wider texture marks. The erratic fluctuations of the friction force and microplowing of the carbon film at steady state are attributed to the relatively large wear particles generated by micropitting.

Transesterification reactions between polyarylate (PAr) and a copolyester (PETG) have been investigated by proton nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry. Blends of PAr and PETG were prepared by melt mixing and solution-casting with weight fractions of PAr in the blends varying from 0.90 to 0.10. The PETG is a copolyester containing ethylene-1,4-cyclohexylene dimethylene terephthalate. From the thermal analysis of the PAr/PETG melt blends, a single glass transition temperature is observed, which indicates a miscibility between the PAr and PETG. The benzene insoluble fraction of the PAr/PETG (50/50) melt blends and solution-cast blends were characterized using NMR and FTIR. The results of NMR and FTIR support the conclusion that transesterification reactions between the PAr and PETG occurred under the melt blending conditions applied., INTRODUCTION Polyarylate (PAr), an amorphous aromatic polyester, which is made from bisphenol-A and isophthalic/terephthalic acids, has excellent mechanical and flammability properties (1). The copolyester (PETG), which is ethylene- 1,4-cyclohexylene dimethylene [...]

Freeze-dried amorphous systems containing trehalose and lysine show significantly more stability to nonenzymatic browning than systems containing sucrose or glucose. The sucrose system has 200 to 2000 times greater rate constants for browning than the trehalose system. Similar rate constants for sucrose and glucose browning at a specific temperature level indicate an occurrence of hydrolysis. The presence of crystalline material in the trehalose system contributes to its stabilization value through its influence on the hydrolysis rate.

Pressure-induced amorphous-phase transitions (amorphization) have been observed in framework silicates like quartz and feldspars. A similar crystalline to highly disordered solid phase transition is reported in this study for two zeolites, scolecite and mesolite. Pressure-induced amorphization is demonstrated using in situ X-ray diffraction and Raman spectroscopy. Before complete amorphization, progressive structural changes are observed below 10 GPa. The transition from the crystal to the amorphous phase is irreversible, and the pressure-quenched samples exhibit Raman spectra that bear strong resemblance to aluminosilicate glasses obtained by quenching a liquid. In some cases, however, decompression from 15 GPa of fully amorphized samples is accompanied by a rim recrystallization of the sample and preservation of an amorphous phase with a structure different from that quenched in other experiments. Shear stresses seem to have important control of the transformation occurring during the decompression of the samples.

A study examined the bathochromic shift of the lowest-energy electronic transition for the polymers' chromophore and on the width of the inhomogeneously broadened absorption band. Comparison of the measurements of the absorption spectrum in atactic polypropylene with the modeling results indicate that ab initio calculations, semiempirical methods and classical simulations techniques can give significant insights into the complex microscopic interactions in amorphous materials,

Development and application of a direct method enables the determination of activation energy, free-energy barrier and activation entropy to nucleation of crystallites in amorphous solid. The method does not depend on the energy barrier to growth. Measurement of the free energy barrier to nucleation of crystallites of amorphous silicon (a-Si) thin films using the direct method yields a value of 2.0 to 2.1 eV, indicating the conversion of a-Si films to intermediate amorphous state and that the activation entropy is not a prominent part of free-energy barrier. The general kinetic basis of the method enables its application to crystallites of any amorphous structure.

Large cystals of the OH end-member of topaz in the F-OH solid-solution series are synthesized between 55 and 100 GPa and temperatures of up to 1000 degrees C using gels of various compositions. The crystals are then subjected to high-pressure experiments, microprobe analyses, single-crystal x-ray diffraction, optical crystallography and infrared spectrometry. The results showed that topaz-OH, the synthetic phase, forms from both amorphous and crystalline starting materials at ambient conditions but breaks down into kyanite at higher temperature and pressure conditions.

Results on the investigation of the propagating 180[degrees] domain walls in bistable amorphous glass-coated microwires with nearly zero magnetostriction are reported for the first time. As-cast glass-coated microwires are bistable only if their metallic nucleus diameter is larger than 20 [micro]m. Glass removal induces bistability in microwires with metallic nucleus diameters below 20 [micro]m. Nearly zero magnetostrictive glass-coated microwires display larger domain wall velocities and mobilities as compared to positive magnetostrictive microwires. Samples that become bistable after glass removal display smaller values of the wall mobility as compared to as-cast bistable microwires. Mobility can be increased by annealing. The experimental results have been explained based on the damping mechanisms of the domain wall motion, specifically on the spin relaxation damping, whose coefficient is proportional to the anisotropy constant from the microwire's inner core. Stress relief determined by glass removal and annealing have been considered. The results are important for future applications of nearly zero magnetostrictive microwires in spintronic devices. Index Terms--Amorphous glass-coated microwires, domain wall propagation, large Barkhausen effect, magnetic anisotropy.

The second harmonic component of nonlinear GMI in soft magnetic wires with helical anisotropy and near-zero negative magnetostriction subjected to different tensile stresses is studied for various current amplitudes (3-13 m[A.sub.rms]) and frequencies (1-3 MHz). In the absence of tensile stress, the dc field dependence of the second harmonic of the voltage across the wire, [V.sub.2f], exhibits a symmetric four-peak structure. The application of increasing tensile stress at relatively low current (3-5 m[A.sub.rms]) causes the [V.sub.2] f signal to convert to a three-peak structure after a complicated series of changes. The three-peak structure consists of two outer peaks (OP) and one small central peak (CP) situated at very low field. When the current amplitude is increased, the [V.sub.2f] signal reverts to the four-peak structure, reversing the same steps. At relatively high frequencies, the [V.sub.2f] signal increases with current amplitude to more than 160 mV at high stress. Using a simple quasi-static model, we were able to qualitatively reproduce the three and four-peak structures and their dependence on current amplitude and tensile stress. Frequency dependence requires a dynamical model, as does precise determination of sizes and positions of peaks. This is being developed. Index Terms--Amorphous wires, helical anisotropy, magnetoimpedance, second harmonic, tensile stress.

Dynamic hysteresis in bistable amorphous wires is studied at frequencies up to 200 kHz. As frequency is increased, the magnetization loop exhibits progressive widening, maintaining its bistable property. The switching process is analyzed within the Neel-Brown theory of the magnetization reversal due to activation over an energy barrier. The frequency dependence of the switching field is evaluated by considering a 'waiting time' for closure domain wall to escape the pinned state, which gives a very good agreement with the experiment. The time of the magnetization reversal decreases with frequency down to few microseconds at 200 kHz, owing to the switching field increase. Index Terms--Amorphons wires, dynamical hysteresis, Neel-Brown model.

The tensile stress dependence of magneto-impedance (MI) in CoSiB and CoFeSiB amorphous wires is reported. A phenomenological model for the transverse susceptibility based on a simple domain structure, and which includes the magneto-elastic energy contribution, is used. The square-root of the transverse susceptibility is assumed to be proportional to the magneto-impedance. The model predicts correctly the form of the stress dependence of the MI-effect, and shows that a significant distribution in the magnitude of the anisotropy constant is needed to explain the MI-response of these wires. Modelling also suggests that at higher excitation frequencies ([greater than or equal to] 1 MHz) magnetic moment rotation is the dominant process controlling the MI-effect.

Alternating current hysteresis loop measurements enable the investigation of the four constituents of the susceptibility tensor of high magnetostrictive amorphous FeSiB wire. The internal stresses produced during quenching are eliminated in the sample by annealing. The samples exhibit extensive Barkhausen jump in bistable magnetic behavior when subjected to tensile torsion and stress.

Two models were used to interpret low temperature calorimetry data and magnetocalorimetry data with respect to amorphous Fe(x)Zr(100-x). The first model dealt with spin fluctuation effects, while the second emphasized superparamagnetic cluster effects. Long wavelength nonmonodispersive magnetics excitations of characteristic energy caused spin fluctuations.

Byline: J.M. Pelletier, C. Gauthier, L. Chazeau Mechanical spectroscopy is a powerful tool for the study of materials. In particular, it is shown that such a technique can help the characterisation of amorphous materials, whatever their nature (polymer, ceramic or metal). It also provides precious information for the understanding of the mechanical relaxations involved in the deformation of these materials. This technique is also useful for the study of semi-crystalline material, their crystallisation process, and when they are filled, the influence of the fillers on this phenomenon. However, through the discussion, it is evidenced that, to provide insightful results, this technique must always be used in parallel with other techniques such as DSC, techniques of microstructural characterisation or mechanical modelling.

The crystallization of amorphous SB3.6Te films (40 nm thick) and five at dot percentage Ge continuing SB3.6Te films (10, 20 and 40nm thick) as studied with transmission electron microscopy using in situ annealing. The nucleation rate of these materials showing growth-dominated crystallization increases with decreasing film thickness and a mechanism is presented which explains this phenomenon.

The solid-phase epitaxial regrowth of 175 ke V Rb(super plus one)-implanted alpha-quartz during thermal annealing in air or O(sub 2)(super 18) was studied as a function of the temperature and the implanted Pb fluence. After the irradiation a continuous amorphous layer grew, which during epitaxy, decreased in thickness by a planar movement of the a/c interface to the surface.

Energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) are explored. Comparison of the three methods indicates that the XPS and EELS methods are the most reliable, yielding a volume expansion of (11.5 plusmn 2)% for the amorphous state in 6H-SiC at 295K.

Recent adavances on cold, noncrystalline water with respect to supercooled and glassy water are discussed. Research indicates that cold, noncrystalline states of water help understand the physics of liquid water in relation to temperature effects. Furthermore, static and dynamic heterogeneities also influence the properties of supercooled water.

This review discusses the experimental and computer simulations on diffusion in metallic glasses and supercooled melts. Research findings show that diffusion in metallic glasses and crystalline metals is significantly different and is mediated by thermally activated, collective atomic processes.