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Yb2Si2O7 is a popular environmental barrier coating; however, it decomposes into Yb2SiO5 in high-temperature steam environments. The thermal mismatch between Yb2Si2O7 and Yb2SiO5 leads to the cracking and failure of the disilicate coating via oxidation. Dispersing SiC nanofillers into the Yb2Si2O7 matrix is suggested to maintain the Yb2Si2O7 matrix and promote crack self-healing. This study is aimed at clarifying the effect of water vapor on the self-healing ability of such composites. X-ray diffraction analysis and scanning electron microscopy were used to monitor the surface composition and the crack formation, respectively, in 10 vol% SiC-dispersed Yb2Si2O7 composites. Annealing at temperatures higher than 750 °C in air or in a water vapor rich atmosphere led to strength recovery and the self-healing of indentation-induced surface cracks owing to volume expansion during the oxidation of SiC. The self-healing effect was influenced by the oxidation time and temperature. Rapid diffusion of H2O as an oxidizer into the SiO2 layer promoted self-healing in a water vapor rich atmosphere. However, accelerated oxidation at temperatures higher than 1150 °C formed bubbles on the surface. Fabricating composites with a small amount of Yb2SiO5 will be a solution to these problems.

The internal structure of heat insulator materials, which were built by mixing micrometer-size α-alumina with nanometer-size fumed alumina though changing their mixture ratios, was inspected using transmission electron microscopy (TEM) tomography and synchrotron radiation nano-tomography. The heat insulator samples formed by two kinds of alumina phase have high porosity that consist of hierarchical structures of nanometer and micrometer size. From TEM observation, it is found that the porosity was 90.7% in the aggregate of fumed alumina with an average particle diameter of 35 nm whilst the average pore size was 70–80 nm. From observation of synchrotron radiation nano-tomography, it is found that α-alumina particles distribute homogeneously in samples that have fumed alumina phase of more than 50 mass%. The effect of internal microstructure on heat insulator properties were considered by performing a simple heat transfer simulation using image based models prepared from synchrotron radiation nano-tomography images. Similar changes in heat transfer with the experiment were obtained by the simulation. Therefore, it is suggested that the change of heat transfer depending on a mixture ratio of α-alumina and fumed alumina is mainly caused by the internal microstructure, that is, the distribution and connectivity of α-alumina phase within fumed alumina phase.

In magnetic-confinement-type fusion reactors, the strong electromagnetic force generated by the superconducting coil is of the order of several tens of MN/m. To support this huge force, a strong and heavy coil support structure is required. The total weight of each magnet designed for conventional fusion reactors or experimental devices is several times greater than the ideal value. In recent years, structural optimization has advanced, owing to improvements in computer-aided design and finite-element analysis. For instance, the topology optimization method contributes novel designs that overturn common sense. In the present study, topology optimization is applied to the design of the magnet system used in a helical fusion reactor to reduce the weight of the magnet while maintaining the mechanical soundness of the component. A weight reduction of more than 25% from the conventional design could be achieved.

Magneto-optical (MO) effects enable non-reciprocal optical components like optical circulators and isolators as well as a magneto-optical spatial light modulator with switching speeds superior to a digital micromirror and a liquid crystal device. To develop a magneto-optical device with high performance, it is desirable to use materials with large rotation angles and small extinction coefficients. In other approaches introduction of nanostructures, magnetophotonic crystals [1] and localized surface plasmon resonance (LSPR) [2] has been shown to provide enhancement of the Faraday effect for distinct wavelengths. This work shows how rectangular arrays of gold (Au) particles embedded into thin films of bismuth-substituted yttrium iron garnet (Bi:YIG) offer different phenomena in comparison with the square arrays previously studied [3] [4] [5]. This enhancement of Faraday rotation was first observed in samples fabricated and characterized experimentally [6].

Substituting effect of CF3 to the Ru-based binuclear complex [{RuIII(acac)2}2(μ-OEt)2], in which S = 1/2 spin dimer takes the singlet ground state have been investigated by means of the magnetic susceptibility χ and the longitudinal nuclear spin relaxation rate T1-1 of 1H/19F-NMR. In CF3-substituted complex [{RuIII(fhma)2}2(μ-OMe)2], we have observed the prominent magnetic response both in χ and T1−1. This behavior is attributed to the slight change in the Ru valence state due to the substitution.

Thermal contraction affects the final geometry of a cold forged product. Control of the thermal geometry changes of aluminum alloys is essential because aluminum alloys have higher thermal conductivity than other metals. Finite element analysis revealed that inhomogeneous temperature distributions cause local heat shrinkage, which lowers the accuracy of the final geometry. An optimal slide motion was proposed to ensure uniform temperature distribution. Simulation results indicated that oscillatory slide motion is superior at ensuring a uniform temperature distribution, and this was confirmed by experiments. Our study showed that process design with consideration for temperature distribution is advantageous.

To inhibit electromagnetic interference problems in next generation wireless communications using millimeter waves, the development of millimeter wave absorbers is crucial. Herein we theoretically designed a millimeter wave absorbing sheet composed of e-GaxFe2-xO3 nanomagnets based on impedance matching calculations. From the previously reported magnetic permeability (μ) of e-GaxFe2-xO3, the artificial frequency dependences of the real (μ') and imaginary parts (μ") were constructed using the Landau-Lifshitz equation. The impedance matching calculation showed that a 217.2 μm thick metal-backed e-Ga0.537Fe1.463O3 sheet perfectly absorbs 60 GHz millimeter wave, while a 201-233 μm thick sheet can absorb 99% of the millimeter wave, i.e., a reflectance loss (RL) of -20 dB. The frequency dependence of RL indicated that the frequency range where RL exceeds -20 dB is as broad as 1 GHz (59.5-60.5 GHz). Such theoretical calculations will be useful for fabricating a 60 GHz-band millimeter wave absorber sheet from the viewpoint of industrial applications.

The helical coil (HC) of a large helical device- (LHD-) type reactor has a non-axisymmetric three-dimensional (3-D) geometry and is wound continuously through the toroidal circumference. A simple calculation method can be useful in the early design phase for estimating the effect of many geometrical and structural parameters on the coil's behavior. An axisymmetric coil model having the mean radius of curvature of the HC has been proposed for estimating the stress distribution inside the coil. To ensure precision, several non-axisymmetric 3-D models were prepared, and the differences among them were investigated. The resulting axisymmetric model can estimate the stress distribution by difference of approximately 20% between the typical 3-D models. However, the deformation can be estimated accurately only by using the 3-D models.

Single layered amorphous carbon nitride (a-CNx) films and a multilayered a-CNx film were prepared by reactive radio frequency magnetron sputtering of a graphite target and nitrogen gas. This paper describes the optical, electrical and opto-electrical properties of the a-CNx films. The optical band-gap of the single layered films increased with increasing nitrogen concentration, which was controlled through the deposition temperature. The photo-sensitivity values, a ratio of photo- and dark-conductivities, ranged from 2.2 to 6.0. In the multilayered film consisting of four a-CNx layers deposited at different temperatures, the photo-sensitivity of the multilayered film was over 1.2 times as compared with that of the single layered films.

Copper sputter-deposition by a newly developed technique called rotation magnetron sputtering is introduced for copper seed layer formation on printed wiring boards (PWBs) as an alternative to the electroless copper plating, which requires many complicated process steps as well as an intentional roughness-induced process to obtain practical adhesion capability between the copper and the resin. A rough copper surface degrades high-speed signal propagation due to an increase in conductive loss, and makes difficult the realization of further miniaturization of copper wirings. Thus, a very smooth surface layer of cycloolefin resin with a low dielectric constant and a low dielectric loss is introduced for realizing high-speed signal propagation, low electrical power consumption, and very high density packaging by introducing PWBs with a new structure, which are characterized by: 1) high characteristic impedance of 100 Ω instead of the current characteristic impedance of 50 Ω, which decreases the electrical power consumption down by one-half and increases the packaging density up to about four times by decreasing the copper wiring width down to one-fourth of the current characteristic impedance of 50 Ω, and 2) multi-resin step copper wiring to simultaneously establish very high density packaging by introducing 10-μm width copper wiring with 40 μm resin thickness and very high speed signal propagation with 80- and/or 120-μm resin thickness copper wiring. By introducing the plasma process steps, such as radio frequency bias Ar/H2 plasma cleaning of the resin surface as well as the exposed inner copper surface, plasma nitridation of the resin surface, deposition of copper nitride, and deposition of the copper seed layer, a copper seed layer with a very smooth surface having very strong adhesion with the resin can be obtained. This technology greatly contributes to next-generation PWBs with very high performance and very high productivity.

The design of a core plasma with the LHD-type heliotron configuration has been advanced. Recent design study of a LHD-type heliotron reactor has shown that the increase in the reactor size is a possible solution to secure a sufficient blanket space. The increase in the reactor size enables a flexible selection of plasma configurations. In this respect, a commercial plant design with the plasma configuration which has a similar shape to that of LHD high-beta plasma discharge was carried out. A parametric scan with a system design code showed that there exists the design window with engineering constraints and the physics constraints which can be extrapolated from the present experimental achievements. Finite-beta equilibrium calculations by VMEC code showed that the last closed flux surface which has almost the same shape as that in vacuum equilibrium can be obtained by applying an appropriate additional vertical field (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The 57 Fe Mossbauer effect measurements were made for the L1 0 ordered Fe–Pt alloys with 39–62 at% Pt and the effect of local atomic environment on the hyperfine structure was investigated. Furthermore, the thermal stability of magnetic order was investigated for the alloys with high Pt concentration. From the analyses of the observed Mossbauer spectra, we found that dipole-field-like anisotropic transferred hyperfine fields are mainly responsible for the large difference in hyperfine field between Fe-site and Pt-site in the Fe-rich alloys. In the Pt-rich region far from stoichiometry, the existence of many Fe-sites occupied by excess Pt atoms causes a distribution of exchange fields. Therefore, the iron atoms in different local environments may have their several hyperfine fields with different temperature dependence. The anomalous temperature dependence of the averaged hyperfine field and line broadening observed for the 61, 62 at% Pt alloys can be understood from the co-existence of various sub-spectra with different temperature dependence. As a result, the thermal stability of magnetic order is largely reduced as the Pt concentration exceeds 60 at%.

The uncertainty in measured diffraction intensities caused by particle statistics, which originates from the limited number of crystallites satisfying the diffraction condition, has been evaluated by a step-scan measurement about the rotation angle of a specimen-spinning attachment of a laboratory powder X-ray diffractometer. The residual statistical variance of the spinner-scan intensity data, after subtraction of periodic drift and variance caused by counting statistics, was assigned to the variance caused by particle statistics. Particle statistics for a standard Si powder (NIST SRM640c) and three size fractions (nominally 3–7, 8–12 and 18–22 µm in Stokes diameter) of quartz powder separated by a sedimentation method have been analysed by scanning electron microscopy (SEM) and the spinner-scan method using a powder X-ray diffractometer. It has been confirmed that the observed ratio of the squared diffraction-peak intensity to the variance caused by particle statistics is proportional to the multiplicity of reflections predicted by the crystal structure. The spinner-scan intensity data for the standard Si powder (NIST SRM640c), the effective particle diameter of which was estimated at 5.6 µm by SEM image analysis, was used as the standard for crystallite-size evaluation of quartz powder based on analysis of spinner-scan data. The effective crystallite diameters of the three quartz powder samples have been estimated at 6.5 (2), 11.7 (2) and 22.8 (2) µm by the analysis of the spinner-scan data, while the effective particle diameters evaluated by SEM image analysis are 7.1, 12 and 25 µm, respectively. Other possible applications of the analysis of particle statistics based on the spinner-scan method are also discussed.

The final optics system of a fast ignition laser reactor concept with a Dry first-wall and a high repetition laser (FALCON-D) is discussed. A cartridge module is proposed for the final optics system. Preliminary neutronics analysis for the final optics systems concept is carried out with the three-dimensional Monte Carlo N-particle transport code MCNP-4C. The total neutron and gamma-ray fluxes attenuate by 4–5 orders of magnitude between inlet and outlet of the duct in the final optics system for FALCON-D. Both of the total neutron and gamma-ray fluxes at the outlet in the final optics system are less then 1.0 × 108 cm−2 s−1, which are about 10 times less than that of the total neutron gamma-ray fluxes at the position just after the shield blanket of the tokamak reactor concepts. Hence, we can qualitatively get the prospect that the cask and hot-cell maintenance, which are proposed for blanket replacement in the tokamak reactor concepts, are also applicable to FALCON-D. The maintenance approach of the final optics system is also proposed. The cartridge module built in the wall of the reactor room can be replaced from the outside of the reactor room. This built-in style cartridge module probably leads an efficient replacement method for the high plant availability.

Large-scale aluminum stabilized superconductors are applied to accelerator magnets, SMES, fusion magnets and so on. Authors have investigated transient stability of large helical device (LHD) conductor, which consists of a NbTi/Cu Rutherford cable, a pure aluminum stabilizer, and a copper sheath, cooled by saturated He I, sub-cooled He I and pressurized He II. The peculiar phenomena, such as "traveling normal zone" and "asymmetrical propagation of normal zone" were observed in the original LHD helical coil and also in small test coils wound with the LHD conductor. These phenomena appeared with He I cooling and were emphasized with He II cooling. In order to investigate the transient stability of LHD composite superconductors against a thermal disturbance and the electromagnetic behavior inside the conductor, the tests with numerical simulations were carried out. In this paper, the effects of the polarity of the external field and the transport current on the direction of the traveling normal zone and the propagation velocity were discussed based on the experimental and simulation results. The hall current distributions in the longitudinal area around the normal zone and their effects on the transient stability were discussed. Important factors in the design of a large-scale aluminum stabilized superconductor were discussed.

The design of a laser fusion reactor with a dry wall chamber has been carried out. According to a simple point model calculation, sufficient pellet gain (G>100) can be achieved with the injection energy of 400kJ under relatively conservative parameters (a=2, η c =0.05, η h =0.2). Assuming the pulse heat load limit of a dry wall to be 2J/cm2, chamber radius ofR=5.64m is achievable..-1-D thermal analysis also supports the feasibility of this design. Then a medium scale plant (400MWe electric output) can be designed with moderate construction cost, which suits for the first-step reactor, if the laser repetition rate can be increased to 30 Hz. Since laser fusion reactors have flexibility in changing its output, this design enables them to be in flexible use according to the time-varying electric demand as the present fossil fuel power plants. This design is remarkable because it gives a new property to the fusion reactors.

This paper reports a highly controllable three-dimensional (3D) sheath flow device for fabrication of artificial capillary vessels. Three step sheath injection type 3D flow device which realizes wide core and sheath structure variations by simply flow rate control was applied to fabricate double-layer coaxial Core-Sheath microfibers applicable for long micro capillary vessels by aligning and cultivating vascular endothelial cells. As a result, about a 3-centimeter-long microfiber which has the vascular endothelial cells fused mutually in the center was successfully formed after three days culture.

A system code for designing laser fusion reactors has been developed, and the design possibility of the laser fusion commercial plant with a single dry wall chamber and a high repetition laser has been examined. In a fast ignition concept, it is confirmed that the target gain G ≥ 100 is achievable with the fusion pulse energy of 40 MJ. If we assume the laser repetition rate of 30 Hz and the pulse heat load limit of 2 J/cm2, the plant which has moderate electric power ( ∼ 400 MWe) can be designed with a dry wall chamber of which radius R = 5.6 m. Although there are several technological issues needed to be solved, this design point can be characterized as a first-step reactor of the laser fusion study because of its relatively low construction cost.

Our neutron diffraction experiments on CePdAl single crystal down to 0.36 K do not reveal any additional magnetic reflections except those which apper below TN=2.78 (4) K and can be indexed with the propagation vector q=(0.5 0 τ). The component τ decreases with lowering temperature and stays constant below 1.9 K. Application of field up to 5.5 T directed along the easy magnetization c-axis shows that geometrical magnetic frustration present in zero field can be lifted. The magnetization process is hysteretic and in agreement with bulk measurements. The observed three field-induced transitions are complicated with signs of domain re-population. The zero-field magnetic structure established after application of field has slightly different magnetic periodicity with respect to the zero-field cooled state.

The α-Mn structure (A12) has been found above 1373 K as a new structure of Fe2VSi, which has the Heusler structure (L21) at room temperature. The Fe2VSi alloy with a single phase of the α-Mn structure was produced using the melt-quenching technique. When the sample was annealed at 1073 K, it transformed into the Heusler structure. In the next step, the Heusler Fe2VSi was annealed again at 1373 K and quenched into ice water, then the sample almost returned to the α-Mn structure. Detail of the crystal structure was investigated on the α-Mn phase by the neutron diffraction measurement. The high temperature α-Mn phase has more complex structure than the low temperature Heusler phase, and it is very unusual transformation because usually a high temperature phase has a simpler structure than its low temperature phase.

Effect of dilution of the U sublattice by non-magnetic Lu on the magnetic anisotropy and magnetostriction of UFe 2 has been studied on single crystals of U 0.8 Lu 0.2 Fe 2 . The observed change of the anisotropy-type from the 〈1 1 1〉 easy-magnetization axis in UFe 2 to the 〈1 0 0〉 axis in U 0.8 Lu 0.2 Fe 2 is accompanied by disappearance of the spontaneous magnetostrictive distortion in U 0.8 Lu 0.2 Fe 2 due to small magnetostriction constant λ 1 0 0 = 0.26 × 10 −3 (at 4.2 K). Nevertheless, the magnetostriction measurements revealed that U 0.80 Lu 0.20 Fe 2 has large λ 1 1 1 = 1.2 × 10 −3 which belongs to a “giant magnetostriction” range.

In Y(Co 1-x Ga x ) 2 quasi-binary compounds, the metamagnetic transition magnetic field becomes lower with increasing x, and the weak itinerant-electron ferromagnetic state is established in analogy with Y(Co 1-x Al x ) 2 . The magnetic moment and the Curie temperature are smaller than those of Y(Co 1-x Al x ) 2 . On the other hand, no evidence of onset of the ferromagnetic state was confirmed in Y(Co 1-x Si x ) 2 compounds with below x = 0.15. The difference in the lattice expansion depending on the substitutional elements brings about the difference in the 3 d-band narrowing and the onset of ferromagnetic state.

Mn2Sb is a ferrimagnet, and substitution of Co or Cr for Mn above the critical concentration results in the appearance of a spontaneous first-order magnetic phase transition from ferrimagnetic (FRI) to antiferromagnetic (AF) with decreasing temperature below Tt . At T

The spontaneous molecular magnetic moment M s =5.15 μ B and the Curie temperature T C =208 K of the uniaxial ferromagnet U 2 Co 13.6 Si 3.4 are considerably lower than that of the isostructural compound Lu 2 Co 13.6 Si 3.4 . The magnetic and magnetoelastic properties of both compounds show no evidence of a U-sublattice contribution to the magnetism.

High-field magnetization up to 47 T and magnetic susceptibility measurements have been performed on a NdCu2Ge2 single-crystal compound. The susceptibility along the c-axis shows an antiferromagnetic behavior and an anomaly at T N =4.7 K . The magnetic easy direction is in the basal plane although moments are directed along the c-axis. The magnetization in the basal plane shows a knee around 6.6 T . The c-axis magnetization shows a metamagnetic transition at 2.3 T . The saturation magnetic moment estimated is 2.7 μ B . An analysis of the crystalline electric field has been made to discuss this magnetic behavior.

The hexagonal compound UCuGe, an antiferromagnet with T N =48 K , exhibits in fields 38– 45 T (at 4.2 K ), applied along the c-axis, a spin-flop transition to a state with a moment of 1.35μB/U. The magnetic susceptibility in fields applied along the basal plane is considerably higher than along the c-axis but no transition occurs in fields up to 42 T applied along either the 〈1 0 0〉 or 〈1 2 0〉 axis. The irreversible (magnetic history dependent) magnetization anomaly observed around 15 T (at 4.2 K ) is attributed to repopulation of antiferromagnetic domains.

DyNiAl orders ferromagnetically below TC=30 K with the Dy magnetic moments oriented along the hexagonal c-axis, and undergoes an order–order magnetic phase transition at T1=15 K where an antiferromagnetic component appears in the basal plane leading to a non-collinear magnetic structure. Magnetization measurements on a DyNiAl single crystal in fields up to 40 T revealed a large uniaxial magnetic anisotropy with anisotropy field of 25 T and field-induced transitions in fields applied along the basal plane. A low-field transition is observed in both magnetic phases and is associated with a rotation of the total magnetic moment toward the field direction to form a canted magnetic structure, which is stable in a wide field interval. A high-field transition is observed only in the low-temperature phase and corresponds to a spin flop of the antiferromagnetic component.

The high-field magnetization curves of single-crystalline YbInCu 4 have been measured along the main crystallographic axes at ambient pressure. Appreciable anisotropy has been found in the magnetization value and in the critical field of the valence transition. We have calculated the magnetization curve and the magnetic phase diagram in the B–T plane using a model of the phase transition between the free Yb 3+ paramagnetic state in a cubic crystal electric field and the low-temperature state with a constant free energy. The calculated results agree well with the experimental data of the high-field magnetization curve. Moreover, we have measured the low-field magnetization process of Yb 0.8 Y 0.2 InCu 4 at low temperature under high pressure and observed an anisotropic ferromagnetic-ordering.

The magnetic characteristics of the single crystal compound TbCu 2 Ge 2 have been studied by magnetic susceptibility and magnetization measurements. The susceptibility shows two anomalies at T N =12.3 K and T t =9.3 K. The magnetic easy direction is the [1 1 0] direction in the basal plane. The magnetization along the easy direction in the basal plane shows a multi-step (at least four steps) metamagnetic process. No significant change of the process is observed at T t . A one-step metamagnetic transition appears around 17 T in the hard c -axis magnetization process. This transition persists above T N up to 25 K where the susceptibility shows a broad peak. The origin is unsolved yet.

Based on the theory of the itinerant-electron metamagnetism, an isothermal magnetic entropy change is discussed for 3d transition metal compounds. The magnetic entropy change depends not only on the magnetization jump at the Curie temperature, but also on the temperature dependence of the critical field of the metamagnetic transition. The isothermal magnetic entropy changes for Co(S,Se) 2 , Lu(Co,Al) 2 and Lu(Co,Ga) 2 are estimated and compared with those observed for MnFe(P,As) and La(Fe,Si) 13 .

Electronic structures of Fe 4 Si 4− n Ge n ( n =0–4) with a cubic B20-type structure are calculated by a self-consistent LMTO method. It is found that these compounds are narrow-gap semiconductors in the non-magnetic state. The band gap is found to decrease with increasing n . For n ⩾2, however, the metallic state with the magnetic moment of about 1 μ B per Fe is shown to be more stable. It is also shown that the characteristic properties of itinerant-electron metamagnetism, i.e., the first-order transition at the Curie temperature and the field-induced metamagnetic transition, may take place at the boundary between the non-magnetic and magnetic states near n =2.

The yield strength of GaN bulk crystals determined directly by means of compressive deformation is around 100–200 MPa in the temperature range 900–1000°C. On the basis of the observed temperature and strain rate dependencies of yield stress, the dislocation mobility at elevated temperatures is evaluated. Deformed GaN shows a drastic reduction of PL intensity, suggesting that newly formed dislocations give rise to non-radiative recombination centers.

A review is presented on the recent advances of itinerant-electron metamagnetism (IEM). By taking into account the magneto-volume effects, spin fluctuation model for IEM based on the Ginzburg–Landau theory is given. A magnetic phase diagram in this system is obtained for the pressure and temperature. It is shown that the Curie temperature depends strongly on pressure near the boundary between the first-order and second-order transitions, while the spontaneous magnetization at 0 K does not depend so much on the pressure, which is a common property in this system. Other field-induced metamagnetic transitions, e.g., between weakly and strongly magnetic states, between antiferromagnetic and ferromagnetic states and between the narrow-gap semiconductor and the metallic ferromagnet observed in FeSi, are discussed based on the basis of electronic structures obtained by band calculations.

Directional luminescence from coupled quantum states of individual ZnSe quantum dots (QDs) in ultrathin single quantum well structure, ZnS/(ZnSe)1/ZnS has been observed. The cause of the formation of the states is the Coulomb interaction between holes in the ZnSe QDs. Despite the random distribution of the sizes and positions of the QDs, the coherent length of the coupled quantum states reaches about 360 nm, which can be estimated directly through the emission angle dependence of the directional luminescence.

In relation to the development of the interfacial area transport equation, this study was aiming at collecting accurate data sets on axial developments of local flow parameters such as void fraction, interfacial area concentration, and gas velocity. The local flow measurements of air–water bubbly flow in a vertical 9-mm-diameter tube were performed by means of a stereo image-processing method. A total of three data sets were acquired consisting of two gas flow rates, 0.013–0.052 m/s, and two liquid flow rates, 0.58–1.0 m/s at six axial locations. The data would be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow.

Metamagnetic behavior has been observed in LiV2O4 powder sample around 38 T at 4.2 K. On the other hand, magnetization for oxygen deficient LiV2O3.92 shows no indication of metamagnetism up to 40 T, and shows substantially reduced magnetic moment compared to that of LiV2O4. These results suggest that ferromagnetic interaction is strongly enhanced by magnetic fields in LiV2O4, whereas antiferromagnetic interaction is dominant in LiV2O3.92., 9 pages, 3 figures, to be published in J. Phys.: Condens. Matter

The influence of an applied magnetic field on the antiferromagnetic transition temperature of the localised metallic antiferromagnet Tb2AgIn has been studied. Magnetisation measurements show that as the applied field strength increases the transition temperature is shifted to lower temperatures with a B2 dependence as expected on the grounds of symmetry. On the basis of measurements made in static fields of up to 5.5 T, it was estimated that a field of 7.7 T would be sufficient to suppress antiferromagnetic order at T=0 K. This prediction has been confirmed using pulsed high field magnetisation and neutron diffraction measurements in an applied field. The magnetic isotherms have a complex field dependence producing an entropy change ΔS which becomes negative above the Neel temperature ∼58 K. The temperature at which the entropy change passes through zero provides a more precise value for the Neel temperature than can be obtained from Arrott plots. Significant magnetic entropy persists above 58 K and specific heat measurements show that the Rln(13) expected for Tb3+ is only recovered at ∼2.5 TN.

The magnetization of Mn2−xCoxSb system with 0⩽x⩽0.35 has been measured under high magnetic fields up to 100 T and high pressure up to 12 kbar . Mn 2 Sb is a ferrimagnet and substitution of Co for Mn at 0.18⩽x⩽0.35 results in the appearance of the spontaneous first-order magnetic phase transition from ferrimagnetic (FRI) to antiferromagnetic (AF) state at T=Tt with decreasing temperature at a critical Co concentration. Below Tt a first-order field-induced AF–FRI transition is observed at a critical field Bc. The critical field Bc is found to decrease with increasing pressure applied at T=4.2 K . The AF state which appeared for the compound with the critical concentration x=0.18 can be transformed to the FRI one by the application of the high pressure of about 16 kbar by increasing the amount of FRI phase. Using the experimental data, the magnetic phase diagrams Bc–T–x and Bc–p–x are determined. The observed magnetic properties and magnetic phase diagrams of Mn2−xCoxSb are explained by the itinerant magnetism of d-electrons and by peculiarities of electronic structure. The itinerant nature of AF–FRI transition is confirmed by specific heat measurements in AF- and field-induced FRI states.

The oscillation and gain characteristics of a longitudinally excited low-pressure F 2 laser in the Vacuum Ultra-Violet (VUV) region are presented for the first time. The low pressure, only 40 Torr (5.3 kPa) with 1.5% F 2 concentration, F 2 laser emits a VUV pulse of 18 ns duration from a ceramic tube 15 cm long and 5 mm inner diameter. Output energy of 140 μJ/pulse was obtained at a charging voltage of 20 kV and an excitation density of 2.3 MW / cm 3 . A time resolved gain measurement was achieved, and a peak gain coefficient of 13.5%/cm obtained. The delay time between the start of the discharge and the start of oscillation was the same as a N 2 laser. No red laser oscillation of atomic fluorine was observed.

We have measured polarized absorption and photoluminescence (PL) spectra of an organic-inorganic semiconductor single crystal, C 10 H 7 CH 2 NH 3 PbI 3 , at low temperatures down to 5 v; K. The temperature and time dependences of the PL intensities have been measured. From these results, it is concluded that quasi-1D excitons are photogenerated in the PbI 3 chain, and some of them are transferred to a triplet exciton in the organic and the others are relaxed to a self-trapped exciton in the PbI 3 chain. The triplet exciton, however, is not transferred to the self-trapped exciton. The lifetimes of the triplet exciton and the self-trapped exciton are estimated to be 1.2 v; ms and 52 v; ns, respectively, at low temperature range, and the former and the latter thermal activation energies are obtained as 9.7 v; meV and 18 v; meV, respectively.

We present a comparative study of magnetism in UCoAl and UNi2/3Rh1/3Al single crystals. UCoAl is commonly believed to be an itinerant 5 f-electron metamagnet with Bc < 1 T with uniaxial anisotropy. Pressure and alloying effects on the ground state point to competing ferromagnetic and antiferromagnetic interactions to be responsible for the non-magnetic ground state. UNi2/3Rh1/3Al is a solid solution between an antiferromagnet (UNiAl) and a ferromagnet (URhAl) and may have a similar underlying microscopic mechanism of the non-magnetic ground state. Possible analogies between the two compounds are discussed.

The temporal behaviour of the photoluminescence (PL) due to excitons and biexcitons have been observed in CuBr nanocrystals (NCs) embedded in poly methyl methacrylate (PMMA). In the excitation intensity less than 0.5 v; µJ/pulse, the decay time of the exciton PL is evaluated to be 30 v; ps. In the excitation intensity more than 0.5 v; µJ/pulse, a new fast component appears in addition to the above component, and the decay time is evaluated to be 0.8 v; ps. In'contrast, the temporal behaviour of the biexciton PL does not depend on the excitation intensity, and the biexciton formation time is evaluated to be about 0.8 v; ps. The facts suggest that two excitons are photo-generated in one NC under a strong pulse radiation, and then a biexciton is formed or one of them is annihilated radiatively without inelastic collision with each other.

Single-phase barium-filled skutterudite compounds, BayFexCo4−xSb12(x= 0 to 3.0, y = 0 to 0.7), were synthesized by a two-step solid-state reaction method. The maximum filling fraction of Ba (ymax) in BayFexCo4–xSb12increased with increasing Fe content and was found to be rather greater than that of CeyFexCo4–xSb12. Theymaxvaried from 0.35 to near 1.0 when Fe content changed from 0 to 4.0. BayFexCo4–xSb12showedp-type conduction at a composition range ofx= 0 to 3.0,y= 0 to 0.7. Carrier concentration and electrical conductivity increased with increasing Fe content and decreased with increasing Ba filling fraction. The Seebeck coefficient increased with increasing Ba filling fraction and with decreasing Fe content. Lattice thermal conductivity decreased with increasing Ba filling fraction and reached a minimum at a certain Ba filling fraction (y= 0.3 to 0.4). The greatestZTvalue of 0.9 was obtained at 750 K forp-type Ba0.27Fe0.98Co3.02Sb12. It is expected that further investigation on the optimization of filling fraction would result in a higherZTvalue at the moderately low Fe content region.