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Anomalous X-ray scattering experiments were performed at Fe-K edge with hexagonal Z-type barium ferrite samples Ba3Co2-x Fe24+x O41 (x=0, 0.2 and 0.4) in order to study distributions of iron and cobalt atoms over ten crystallographically different sites in the structure. The results were consistent with those determined by the neutron diffraction technique combined with the Rietveld analysis and with those by extended X-ray absorption fine structure (EAXFS) analyses.

Magnetic nanocomposites in which iron nitride nanograins were dispersed in a silver matrix were synthesized by nitriding iron oxide nanograins buried in the matrix. The ammonia-flow method, in which the solid phase reacted with flowing ammonia, was adopted for this synthesis. Several reactions of metallic iron with NH3 were carried out under various conditions and the resultant nitride phases were observed by X-ray diffraction (XRD). Based on these results, optimum conditions for the synthesis of the nanocomposite were determined, and a nanocomposite containing only γ'-Fe4N or ε-Fe2–4N was successfully obtained. Phase identification of iron nitride in the composite was performed by X-ray absorption near-edge structure (XANES) measurement, which was found to be more suitable for the present nanocomposites than XRD.

A superparamagnetic nanocomposite of silver and iron oxide was synthesized by gas condensation. The procedure involved (1) coevaporation of silver and iron, (2) in situ oxidation of iron particles, (3) in situ compaction, and (4) post-annealing in an inert or an oxidizing atmosphere. The magnetization plots against H/T fell on a single curve from room temperature to 160 K, thereby providing evidence of superparamagnetism. Annealing treatment modifies the effective magnetic moment size and saturation value of magnetization. The present process is a potential synthesis route for magnetic nanocomposites useful for applications such as magnetic refrigeration, recording and permanent magnets.

The structure of nano-phase silver particles was investigated by fluorescence EXAFS over several sizes of particles. The particle concentrates (>1021part./m3) were prepared using the aerosol process associated with surfactant coating to maintain the isolation of each particle. The EXAFS of the particles showed a good signal-to-noise ratio even in the particles less than 3 nm in diameter. The nearest neighbor distances of silver atom in the particles and foil were 0.289 (±0.002) nm for all the cases, and no distinct shrinkage of the atomic distance was observed for the silver particles in the size range of this work.

A study of reflection Fourier Transform IR (FTIR) microscopic analysis with the probe area of 0.1×0.1 mm was conducted on a polycrystalline YBa2Cu3O y pellet irradiated with 1060 nm laser light. The presence of a large increase of the broad IR band accompanied by the simultaneous disappearance of the 590 cm-1 phonon band in the CuO2 plane, was found on an insulator sample irradiated in an atmosphere of 650 Torr oxygen gas, but not on a sample in 650 Torr Ar. This suggests that oxygen doping into YBa2Cu3O y occurs due to the laser irradiation to result in the increase of charge carriers in the CuO2 plane. A small increase in a narrower IR band showing a peak around 1000 cm-1, and considered to originate from the direct photoexcitation was also found in both of the samples.

Direct observation of 18O tracer diffusion by secondary ion mass spectrometry (SIMS) was made on a single crystal of YBa2Cu3O y with an array of steps on the stairlike surface. The unique distribution of the diffused 18O in the ab-plane and in the c-axis direction was shown visually as a mapped image, which revealed some fundamental processes on the oxygen penetration through the surface and diffusion in the inner crystal. It was found that at 530°C, the diffusion coefficient in an ab-plane is larger than that in a c-axis direction by more than five orders of magnitude.

A breakthrough experiment was used to investigate the recovery of hydrogen isotopes from contaminated inert gases by using a reactive uranium powder bed column under various conditions. Before the break point the partial pressure of hydrogen in the outlet gas is almost equal to the plateau pressure of UH3 at the column temperature. The breakthrough curve can be described by Meienschein's gas phase mass-transfer-limited model. The column is still effective at 273 K where the partial pressure of hydrogen at the outlet is 10−5 Pa.

A thin titanium layer with uniformly absorbed tritium (T/Ti ~1.0) was bombarded by 390 keV D 3 + ions (130 keV per deuteron). Bombardment was performed at low (111 K) and room temperatures up to fluences of 5.9 × 10 18 D / cm 2 and 3.0 × 10 18 D / cm 2 , respectively. Depth profiles of tritium up to a depth of 0.8 mg/cm 2 (~1.8 μm) were measured and the change of the profile with fluence was investigated by means of the T(d, α)n nuclear reaction. At both of the temperatures, a dip was formed on the depth profile of tritium at the depth around the projected range, indicating that the deuteron bombardment induced the migration of tritium against the concentration gradient. At the low temperature, the dip showed a gradual growth with fluence and saturation of the growth at the higher fluences, which could not be described by the existing model for isotope mixing. The spectrum of protons from the D(d, p)T reaction obtained in the same measurement suggested that the release of deuterium suddenly started at the final stage of the present bombardment. The dip formed at room temperature was larger than that at the low temperature. The migration of tritium induced by the bombardment is discussed on the basis of the experimental results obtained.

Preparation of stoichiometric TiS2 was attempted at 1000°C under high pressures. TiS2 was firstly formed accompanying nonstoichiometric TiS2 from the starting stoichiometric mixture of Ti and S. The further reaction to stoichiometric TiS2 takes much longer time than the reaction of equimolar mixtures of Ti and TiS3. The reaction of Ti and TiS3 gave an almost stoichiometric TiS2 at 1000°C after the duration of 2hrs.

In-situ measurements of the depth profiles of tritium in a titanium tritide target for generating 14-MeV neutrons have been made with the method of the ion beam analysis using the T(d, α)n nuclear reaction. The initial distribution of tritium in the unirradiated target has been observed to be nearly uniform over the depths. After the irradiation of 390-keV D3 + ions at a temperature of about 10°C a dip has been found in the depth profile around the depth of the projected range of the ions. By the successive isochronal anneal-ings at temperatures below 130°C the tritium has been uniformly redistributed. The behavior of tritium in the target and the effectiveness of the depth profiling for evaluating the energy spectrum and the yield of source neutrons are discussed.

In order to examine the reliability of optical fiber systems in nuclear power plants, we estimated the induced losses of pure silica core and GeO 2 added core single mode optical fibers (Si-SMF and Ge-SMF) exposed over a long period to low dose rate γ-rays (less than 100 R/h, 40 yr). Also γ-ray induced losses under a high dose rate and high temperature condition such as 10 6 R/h and 200 o C were estimated in view of an accident. In both cases, the induced losses were concluded to depend mainly on total dose from the results of low dose rate irradiation experiments and a study on temperature dependences of induced losses

Gamma-ray induced losses of pure silica core and GeO2 added core single mode optical fibers (Si-SMF and Ge-SMF) at 1.30 μm were investigated. Kinetic study on recovery curves of their γ-ray induced losses, showed that the induced loss could be divided approximately into two terms: one is dependent mainly on total dose and the other is dependent on dose rate, which has a tendency toward saturation when increasing total dose and was also represented by 3 components with different relaxation times The former term which is dependent mainly on the total dose was found to be due to IR tail absorption caused by irradiation and to be associated with the Si-E′ center for the Si-SMF and the Ge(l) and Ge(2) centers for the Ge-SMF, respectively.

Monoclinic NbS/sub 3/ prepared under high pressure was used as the cathode in a lithium secondary battery. In the first discharge, the cell showed an almost constant voltage of ca. 1.8V until the discharge capacity corresponding to the uptake of 1.7 Li per NbS/sub 3/ was achieved. In constant current cycling carried out between 2.7 and 1.5V, this cell had a larger discharge capacity than that using triclinic NbS/sub 3/ prepared by a conventional method. The capacity difference was 0.2-0.3 Li per NbS/sub 3/. X-ray diffractometry of monoclinic NbS/sub 3/ cathode after 120 cycles suggested an accumulation of intercalated lithium in the NbS/sub 3/. The cell was also rechargeable in the compositional range of x=2-3 Li/sub x/NbS/sub 3/.

Intercalation into TiS/sub 2/ has been extensively investigated and was applied as cathode reaction of lithium secondary battery. There have been many publications on this topic. However, it was not easy to obtain stoichiometric TiS/sub 2/ due to its variable compositional range and the presence of higher sulfide, TiS/sub 3/. Thompson et al. verified the existence of stoichiometric TiS/sub 2/. Its fine powder was then prepared from a titanium sponge between 450/sup 0/ and 600/sup 0/C in a temperature gradient which fixed the sulfur pressure. Nonstoichiometry affects the discharge property of lithium battery. Winn et al. prepared single crystals of Ti /SUB x/ S/sub 2/ (x = 1.002, 1.01, 1.02) and electro-intercalated lithium and sodium in propylene carbonate. They measured open-circuit voltages and chemical diffusion coefficients of alkali metals as a function of alkali content. Whittingham reported discharge curves of lithium battery in 70% tetrahydrofuran and 30% dimethoxyethane mixed solution using TiS/sub 2/ and Ti /SUB 1.1/ S/sub 2/ as cathodes. They also found that excess titanium reduced the diffusibility of intercalated lithium. Selection of solvent is important for the development of an ambient temperature secondary battery. 2-Methyltetrahydrofuran-LiAsF/sub 6/ was found to be superior to the electrolytes based on propylenemore » carbonate, methyl acetate and tetrahydrofuran for the lithium electrode cycling efficiencies (7). However, the effect of solvents has not yet been comparatively investigated on intercalation battery using TiS/sub 2/ having various Ti/S ratios. In the present study, samples having compositions of Ti /SUB x/ S/sub 2/ (1.00 less than or equal to x less than or equal to 1.13) were prepared and the discharge properties of lithium batteries were galvanostatically investigated using lithium perchlorate as the electrolyte in several kinds of organic solvent. The discharged products were characterized using powder x-ray diffractometry.« less

Fetal heart rate and beat-to-beat variability during fetal breathing movements were investigated by abdominal fetal electrocardiography. The mean (M-RR) and the standard deviation (SD-RR) of R-R intervals and the percentage of absolute beat-to-beat differences below 2 msec (2 msec %) were measured by computerized quantification. Fetal breathing movements were associated with a significant increase in SD-RR (from 8.73 ± 5.59 during apnea to 16.7 ± 5.67 during breathing) and a significant decrease in 2 msec % (from 44.1 ± 12.4 during apnea to 27.9 ± 8.65 during breathing). According to discriminant analysis, the 2 msec % was the best coefficient for classifying fetal breathing episodes. Thus the determination of 2 msec % is useful in assessing fetal heart rate variability by abdominal fetal electrocardiography.

It was found that sonochemically prepared metal particles such as Ag, Pd, Au, Pt and Rh are of nanometer size with a fairly narrow distribution (e.g., about 5 nm for Pd particles obtained from a 1.0 mM Pd(II) in polyethylene glycol monostearate solution). We have suggested three different reduction pathways under sonication: (i) reduction by H atoms, (ii) reduction by secondary reducing radicals formed by hydrogen abstraction from organic additives with OH radicals and H atoms, (iii) reduction by radicals formed from pyrolysis of the additives at the interfacial region between cavitation bubbles and the bulk solution. The reduction of Ag(I) and Pt(II) mainly proceeds through reaction pathway (ii). In the cases of Pd(II) and Au(III), the reductions mainly proceed through reaction pathway (iii). The reduction of Rh(III) was not achieved under the same conditions; however, by the addition of sodium formate, reduction occurred and the preparation of Rh particles succeeded.

A composite nanoparticle material was synthesized by gamma-ray irradiation of an aqueous solution containing gold ions and dispersing iron-oxide nanoparticles. Gamma-ray irradiation induces reduction of gold ions in the solution to form metallic gold, which are stabilized at the surface of iron-oxide particles. TEM observation indicated that many gold grains of 5 run surround each iron oxide particle. A reddish color due to the surface plasmon resonance of nano-sized gold was seen in an aqueous dispersion of the composite particles and attracted by a magnet, which indicates a connection of gold and iron-oxide in the nanoscale. The surface of gold in the composite particles was found reactive with the mercapto group and to adsorb glutathione and two amino acids possessing sulfur preferably out of seventeen amino acids. The iron oxide surface was substantially covered up with gold grains grown from the seed grains initially deposited by the gamma-rays. The synthesis procedure, characterization, and the tests of the molecule adsorption are described.

We successfully synthesized M-(BaFe12O19) and Co2Y-type (Ba2Co2Fe12O22) hexagonal ferrite nanoparticles by the technique of ultrasonic spray pyrolysis. Starting solution was a mixture of iron, barium and cobalt nitrates and deionized water with stoichiometric composition of hexaferrites. The products were collected by use of an electrostatic precipitator. Effects of temperature and gas-flow rate on occurring phase and grain morphology were investigated. The product was characterized with XRD and SEM experiments. Single phase materials of these hexaferrites with particle size of 100 nm-1μm were obtained at lower temperature. These experiments indicate that the gas-flow rate influences on the formation temperature and that the temperature in heating zone affects grain morphology of resultant particles.

The magnetocaloric effect of super-paramagnetic nanocomposites composed of iron-oxide nanograins dispersed in a silver matrix was studied by evaluating the magnetic entropy change ΔS induced by demagnetization. The nanocomposites were synthesized by inert gas condensation techniques, and their grain sizes are 10–35 nm. The values of ΔS obtained by calculation from magnetization data sets and from a theoretical formula based on the Langevin super-paramagnetism model were compared. The behavior of ΔS agrees fairly well with that predicted by the Langevin model at relatively higher temperatures T and lower magnetic fields H. At lower T or higher H, ΔS deviated from the model. The deviation was examined and ascribed to exchange coupling and crystalline anisotropy, which hinder the fully random spin orientation state at zero field. The evaluated ΔS values of the nanocomposites were larger than those of the paramagnet containing Fe3+ by about two orders of magnitude, indicating a clear enhancement of the magnetocaloric effect due to the nanostructure.

The metal particles of an interstitial solid solution of palladium carbide, PdCx (0 < x ≤ 0.15), were synthesized at room temperature in aqueous solution during the reduction of tetrachloropalladat...

Hydrogen gas evolution from water dispersing nanoparticles induced by 60Co gamma-ray irradiation was studied. Nanoparticle of TiO2 with average size of 30 nm was examined. It was indicated that the hydrogen yields were affected significantly by pH of the dispersion. Difference in agglomeration could explain the difference in hydrogen yields. Reactions that enhance the hydrogen yields were discussed, and it was concluded that the radiolysis process is dominant in the total enhancement mechanism.

We have tried to obtain evidence for electrolytically induced cold nuclear fusion by detecting charged particles associated with the nuclear reaction. Charged particles were detected by a conventional silicon surface barrier detector attached close to the thin foil cathode which formed the bottom of an electrolysis cell. The efficiency and signal-to-noise ratio of this system are higher than those of neutron detection systems, which made it easy to determine whether the fusion occurred or not. The energy spectrum measured with the electrolysis of D2O suggested that the nuclear reaction took place in palladium cathode.