The superconducting transition temperature (TC), and the Hall coefficient (RH) at room temperature (RT) and 77K were measured under hydrostatic pressure up to 1.2GPa for La2CuO4+δ system, where δ=0.015-0.108. Anomalous δ-dependence was observed in the RH, which suggests a change in the electronic system. At 77K, there was little pressure effect in the RH irrespective of δ-value. At RT, however, there was positive pressure dependence for the intermediate δ values between 0.060 and 0.080. The TC of the 15K phase showed a negative pressure effect of -2 to -6K/GPa. The TC of the 32K phase, however, showed a large positive pressure effect of 7 to 16K/GPa. The TC of the 44K phase had a positive pressure effect.
High-temperature oxidation behavior of Fe-20Cr-4Al alloys with 3, 7, 35, 53, 104, 171, 185, 491, 1300 and 6300ppm of sulfur was studied for 18.0ks in oxygen at 1273, 1373, 1473, 1573 and 1673K by mass change measurements, observation of surface appearance of the alloys, X-ray diffraction, scanning electron microscopy and electron probe microanalysis. Mass change of the alloys increased roughly with increasing oxidation temperature. However, the mass changes of the alloys with 7, 35 and 53ppm of sulfur at 1473K, with 7, 35, 53 and 104ppm of sulfur at 1573K and with 7ppm of sulfur at 1673K showed negative values. This fact was in good agreement with spalling of the oxide on the alloys. On the other hand, mass changes of the alloys with more than 171ppm of sulfur decreased with increasing content of sulfur at 1673K. The oxide adherence of these alloys with more than 7ppm of sulfur may be attributed to the size and shape of chromium sulfide particles at the oxide/alloy interface.
It is very important to evaluate the brittleness of Al6Li3Cu quasicrystal. Thus, we evaluate the brittleness of Al-Li-Cu quasicrystal alloy. The evaluated value of critical energy (Ef) is 5.6erg which value is smaller than cover glass and larger than Si wafer.
The gels has lately attracted attention as functional materials of actuator, sensor and artifical muscle, etc. But their mechanical response and strength are still insufficient to apply these as functional materials. Hence, we synthesized gels with good response, and investigated their bending rates in electrolytic solutions by impressing electric field. We prepared Polyallylamine-metacryl acid, sodium salt gels (PAlAm-MAANa gels) from Allylamine phosphate, Methacrylic acid and N, N′-methylene-bis-acrylamide, and measured its bending rate in electrolytes solution under electric field. The result, the PAlAm-MAANa gels (PAlAm ratio; 50% and MBAA ratio; 7%) indicated bending rates of; 21.00°/s. Thus, the PAlAm-MAANa gels were found to be applicable to actuator and artifical musle as new functional materials.
The granular-ice making method for cool-heat storage has been experimentally investiguted. Granular-ices were formed through injecting water droplets into a low temperature immiscible coolant whose specific gravity is smaller than water. As a low temperature immiscible coolant, kerosine or mixture of kerosine and engine oil has been utilized, where oil concentration was ranged from 0 to 40% in volume. It was found that the granular-ice can be successively produced even at -5°C. Above at -5°C, the ice-bridging phenomenon occurred for any concentration measured. Optimum conditions for succesive production of granular-ice were obtained as follows. 1) circulation of the mixture of kerosine and engine oil, and 2) no circulation of kerosine only. The effect of coolant temperature and viscosity on the successive production of granular-ices were discussed.
High-temperature oxidation of sintered Cr2S3 was studied for 18.0ks in oxygen at different temperatures from 773 to 1673K. Mass change of the Cr2S3 decreased with increasing temperature of oxidation and decreased gradually after oxidation at more than 973K. Identified oxide in the Cr2S3 was only Cr2O3. Amount of Cr2O3 increased with increasing temperature of oxidation.
A CoSb3 compound with a skutterudite structure (MX3) is one of promising thermoelectric materials. In this study, the preparation of CoSb3 thin films on glass substrates by the RF-magnetoron sputtering method has been researched. By using a Co-target and a Sb-target, simultaneous and alternate sputtering methods were carried out. Single phase CoSb3 thin films have been successfully obtained under the following conditions; (1) annealing at 200°C in a vacuum after simultaneous sputtering, (2) annealing at 400°C in a vacuum after making multilayered Co/Sb/Co/Sb films by alternate sputtering.
New (Nb, Ta)3Sn conductors with excellent high-field performance have been fabricated using Ta-Sn powder as a core material. The Ta-Sn powder was easily synthesized by the melt diffusion reaction between Ta and Sn powders. The powder was encased in a Nb or Nb-Ta alloy sheath to form a composite, and then fabricated into wire and tape specimens. The resulting specimens were reacted at 800-925°C in vacuum. After the reaction a thick (Nb, Ta)3Sn layer, several tens micrometers in thickness, is formed between the sheath and the core. No void is formed in the core after the reaction. Ta is incorporated into the (Nb, Ta)3Sn layer from both the Ta-Sn core and the Nb-Ta sheath. The Jc of the (Nb, Ta)3Sn layer reaches 5×104A/cm2 at 23T and 4.2K. The tape specimens show large critical current at 23T due to the large thickness of the (Nb, Ta)3Sn layer.
We evaluate a permanent magnet by using a High-Tc (Y-Ba-Cu-O) superconductor. As results, it is an anti-magnetism permanent superconducting magnet, and we calculated saturation of magnetic density of 1.8kG by using Jhonson-Mehl equation.
An actuator function using shape memory effect was studied for bi-ceramics glass. The reversible shape memory effect (SME) was found in the temperature range from 200 to 300°C. We conclude that the bi-ceramics glass is useful for creating a new type of actuators which can be operated within the medical micromachine in human body and corrosive environment.
Glass (plastic polymer) normally transforms to supercooled liquid (rubber) above the glass transition temperature (Tg). The transition causes the shape recovery effect. We have studied the shape recovery effect of SiO2 glass. The shape recovery effect was found in the temperature range from 770K to 1170K. The SiO2 glass can be a new actuator which can be operated at high temperature.
White radish sprout was used for the sample to study the effect of tourmaline on growth of plants. The samples with tourmaline-treated distilled water grew even more than that with ordinary distilled water. Furthermore, we discussed that the various tourmaline effects are induced if the tourmaline breaks up water cluster apart.
CuInSe2 single crystals have been grown by synthesis solute diffusion method with controlling the growth rate. Effects of the Cu/In in solvents and the temperature of Se source on the purity of grown crystals have been studied. The single crystal with lower carrier density of -1017cm-3 was found to be grown from a stoichiometric solvent (Cu/In -1.0) when the temperature of Se source was 743K.
Among Cu-based compound semiconductors of Cu3-Sb-VI4 (VI=S, Se), Cu2-IV-S3 (IV=Ge, Sn) and Cu2-Zn-IV-Se4 (IV=Ge, Sn), single phases of Cu3SbSe4, Cu2SnS3, Cu2ZnGeSe4 and Cu2ZnSnSe4 were synthesized from respective melts, and single crystals of those four compounds were grown. Optical band gaps of Cu2ZnGeSe4 and Cu2ZnSnSe4 were determined by optical absorption measurements to be 1.64 and 1.40eV, respectively. From the temperature dependence of electrical resistivities, thermal band gap of Cu3SbSe4 was estimated to be 0.22eV.
Parameters for the laser theraphy of hyperpigmented skin have not been established due to the difficulty to determine the optimum laser intensity. We tried to find out optimum irradiation conditions by using an acoustic shockwave generated at the laser treatment of a hyperpigmented skin. A skin model was fabricated to simulate the laser treatment of human skin.
Photo-electric plethysmograph has been widely used to measure caradiac pulse rate. However, the sensing device is remained without any improvement, even though the opto-electronic technology has been highly refined recently. In order to get rid of low-temperature burn, which is often experienced in long-term, continuous applications, and to guarantee motion-free measurements, we develop a new type of photo-electric sensing device. The dcesign criteria and the merit of the prototype device are discussed in some detail.
The pond snail Lymnaea stagnalis is capable of learning the sequential event of light and rotation. Neural circuit, however, involved in this behavior has not been identified, we examined the relationship between photoreceptors and statocyst hair cells with the physiological and morphological techniques.
In order to analyze the autonomic functioning during sleep, all night polygraphic measurement including the pulse transit time (PTT) was carried out with healthy subjects under sleep deprived and natural sleep condition. Sleep stages were classified based on the EEG recordings. Average and standard deviation of the PTT were calculated in each segment. Effect of sleep deprivation on the autonomic function was investigated.
Relationships between MTS and sleep stage distribution were investigated. Polygraphic measurements were carried out with healthy subjects under sleep deprived and control condition. Results showed that relative frequency of sleep stage 2 and stage REM before the MTS period changed under sleep deprived condition compare with control condition.
The purpose of this study is to investigate the change of autonomic functioning induced by an emotionally stimulating game. In the game, subjects were asked to give words which can be classified designated category in limited time. The pulse transit time were measured and analyzed before, during and after the game. Characteristics of autonomic functioning in mentally cornered condition were discussed.
Artificially evoked somatosensory illusion was investigated. Using synchronized stimulation to the Phantom arm, duration of the illusion and positioning error were measured. Emotional effects of the cutter knife on illusionary sensation were discussed.
The purpose of this study is to investigate the visual process receiving the 3D stereographic pattern with conflicting figures. The visual stimulation induces two possible perceptions of 3D vision and binocular rivalry. Time feature of the dominance of two kind of vision was analyzed. The visual process in ambiguous situation was discussed.
Crystal growth processes of hen-egg-Lysozyme under high static magnetic field were studied by microscopic interferometry and dynamic light scattering measurements in order to control the crystallographic orientation. As a result, orientation of the crystals was obviously controlled by the direction of a magnetic induction under 6T, and few differences of the growth rates were observed from several nm to 400nm in the Lysozyme diameters under 0.6T.
High-temperature oxidation of Fe-20Cr-4Al alloy purified by floating zone melting was studied for 18.0ks in oxygen at 1273, 1373, 1473, 1573 and 1673K. Mass changes of 0.99ppmS and 1.84ppmS alloys increased with increasing temperature of oxidation. On the other hand, mass change of 3.88ppmS alloy showed negative values after oxidation at 1473, 1573 and 1673K, because of spalling of oxide on the alloy.
Oxidation of Fe-20Cr-4Al alloys with small amounts of sulfur and reactive elements was studied for 360ks in air at 1573K. Mass changes of the alloys with up to 185ppm of sulfur were 2.7-3.4×10-2kg/m2. Mass changes of the alloys with 1300 and 6300ppm of sulfur showed small values compared with the other alloys with sulfur. This result was in good agreement with spalling of oxide films on 1300 and 6300ppmS alloys. Mass changes of the alloys with sulfur and yttrium were 2.3-3.0×10-2kg/m2. On the other hand, mass changes of the alloys with sulfur and hafnium showed almost negative values because of marked spalling of oxide films on these alloys.
Lead-zirconate-titanate (PZT) was prepared by a sol-gel process. As one process, lead acetate, zirconium tetra-n-butoxide, and titanium tetra-iso-propoxide were used as raw materials. 2-methoxyethanol and diethanolamine were used as solvents. As another process, lead acetate, zirconyl nitrate, and titanium tetra-n-butoxide were used as raw materials. Distilled water, acetic acid, and tri-ethylene glycol were used as solvents. PZT were synthesized twelve ways on the basics to the two processes. Synthesized PZT by each had been dried for 24h at 338K. Dried samples had been sintered for 1h at 773K, 873K, and 1023K in air. The sintered samples were evaluated by X-ray analysis.
In this study, CrSi2 ceramics were prepared by hot-pressing. The influence of temperature on the electrical conductivity of CrSi2 sintered body was investigated. The samples were sintered at 1273K to 1373K for 3.6ks in vacuum under a pressure of 40MPa. The relative density of sintered body at 1373K was approximately 99%. The high temperature electrical conductivity measured using a D. C. four-terminal method.
The reactivity of fused silica glass (SiO2) with plasma irradiation was investigated using argon gas sheet plasma in order to examine the suitability of this material for semiconductor and nuclear fusion application. The surface of the samples was evaluated using scanning electron microscope (SEM) and noncontactive three-dimensional roughness meter (ZYGO). Surface deterioration was observed by the plasma irradiation with decreased Ar gas flow rate. It was able to suppose this reason, the electron density in sheet plasma increased with decreasing Ar gas flow rate.
Titanium-aluminum alloys are favorable as superb light-weight and heat-resistant structure materials, and is also expected as structure material of a part of body of round-trip spaceships. We measured states of structures by investigating electric resistance and X-ray diffraction pattern. The hardness was measured in contrast with these results.
Quasicrystal has some interesting properties due to its quasiperiodisity, which include higher hardness, higher electrical resistivity, and so on. We know that Al5-Li3-Cu has stable quasicrystalline phase. So, we investigated the formation of Al-Li-Cu quasicrystalline phase at various temperatures by making TTT curve. In this way, we could obtain the fundamental knowledge about the self-organization of the phase. The reason for the stability of the phase is discussed in terms of the quasicrystal growth kinetics.
Hardness of Zr-Al-Ni-Cu glass, which alloy is characterized by a smaller critical cooling rate, was measured in the heating process from RT to 773K. Along the increasing temperature up to 673K, the Vickers hardness decreased to one half of that at RT. At higher temperature, crystallization resulted in a drastically increased hardness.
The collision energy generates the electrical potential of PZT. As the value of the energy increases, the electrical potential becomes higher. We often find the opposite electrical potential. Thus, we investigate the electrical potential. When the residual strain is relaxed enough, we can explain that the integrated electrical potential approaches to zero. This may induce the opposite potential.
Image charge interaction reported by Ishii et. al.1 at Cu/Y2O3-fully stabilized cubic ZrO2 interfaces produced in the thermal evaporation method, was reproduced on a personal computer simply with classical electrodynamics. The difference in the interfacial adhesion force was observed between continuum/ZrO2 (110) (a neutral plane) and continuum/ZrO2 (001) (polarized plane) even if no quantum mechanical computation was done. Continuum/ZrO2 (001) showed stronger adhesion force than that of continuum/ZrO2 (001) at large interfacial interval. This result indicates that the image charge interaction works in a long range.
In recent years, high temperature ceramics as materials with high strength and high melting point are drawing the attention for ceramists. These ceramic materials are expected to be used as a fireplace for nuclear fusion, aircraft engine, rocket nozzle and fireplace material for high temperature incinerator. High-temperature oxidation behavior of sintered Cr3C2 body was studied in air at 300-1400°C for 5min to 25h by measuring mass gain and X-ray diffraction. In spite of increasing temperature and time, weight gain by the oxidation of sintered Cr3C2 body was not approved at 1400°C. However, the oxidation was admitted by X-ray diffraction analysis at higher then 600°C.
PLZT powder for ferroelectrics ceramics was prepared by a sol-gel method with lead acetate (Pb(C2H3O2)2). The crystallization of the sample could be controlled through the low heating process. Based on the results of the X-ray diffraction analysis, good crystallized PLZT peaks was observed of the sample heated at 850°C.
Carbide ceramics has various desirable properties, including such as a high melting point, a high hardness, the electrical conductivity, and chemical stability. In this study, Cr3C2 ceramics prepared by hot-pressing. The influence of temperature on the electrical conductivity of Cr3C2 sintered body was investigated.
Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is common superplasticity ceramics and its deformation behavior at high temperatures is influenced strongly by trace impurities such as silica and alumina. Low purity materials more than 0.1% show only one region of stress exponent 2, while high purity materials show two deformation behavior region with stress exponent 2 at high stresses and 3 at low stresses. In the present study, another deformation region with stress exponent 1 at lower stresses is observed in high purity 3Y-TZP, by means of constant cross-head speed compression tests and constant load compression creep tests.
Tensile strength of platinum alloys containing 5-20 mass% Rh were measured in temperature range of 300-873K. Both tensile strength and elongation decreased gradually with increasing temperature. The hardness was also measured using a micro hardness test, which decreased from HV103 at 373K to HV43 at 1273K. At the hardness of HV=50 and at the higher temperature, strongly increased brittleness was observed from the shape of indentation.
Various steels are prepared for a carburization in ferrite phase. Effect of alloying elements (Cr, Mo, V) for surface hardness was investigated in this study. The steel containing V and Mo increased the surface hardness to HV 550 approximately. No effect was obtained for the steels with only Cr and also with Cr and Mo.