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The switching behavior of ferroelectric polarization of magnet ferroelectric YMnO₃ epitaxial films at around the Néel temperature was investigated to discuss the effect of antimagnetic ordring on the ferroelectric polarization behavior. The polarization-electric field (P-E) hysteresis loops of the films were measured in the frequency range from 1 Hz to 10 kHz and the temperature was varied from 10 to 150 K. Frequency dependence of coercive electric filed (Ec) accorded with Ishibashi-Orihara's theory at the measured temperature range. On the other hand, temperature dependence of Ec disagreed with Devonshire's theory below 120 K, which was close to the Néel temperature of the YMnO₃ epitaxial film.

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BaTiO₃ (BT) ceramics are prepared by spark plasma sintering (SPS) and conventional sintering. In conventional sintering, the density and grain size of the ceramics increase with sintering temperature. In SPS, ceramics with more than 97% relative densities can be obtained by sintering at 900 ˚C for 5 min in air atmosphere. Grain growth is suppressed in the ceramics prepared by SPS, compared with the conventional sintering. The average grain size of the BT ceramics obtained by SPS and subsequent annealing at 1000 ˚C for 12 h was less than 1 m. The ceramics exhibit a high relative dielectric constant of 6020. The field-induced displacement of the BT ceramics is larger than that of the ceramics sintered conventionally. The dynamic strain/field at 15 kV/cm was 540 pm/V.

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The improvement of the valence electron energy loss spectrum has been investigated by the deconvolution technique using the Richardson-Lucy algorithm. The full width of half maximum has been improved from 1.2eV to 0.4eV. It makes possible the precise analysis of the joint density of state which indicates the interband transition as well as the plasmon excitation between the valence and the conduction bands.

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The volumetric efficiency of BaTiO3-based multilayer ceramic chip capacitors (MLCCs) has been steadily improved and significant progress has been made in the solid-state synthesis of fine BaTiO3 powders by optimizing the reaction conditions especially using submicron-sized raw materials and high-dispersion technology. However, further precise diffusion-control based on the kinetics and mechanism of the solid reaction is crucial to achieve higher tetragonality applicable to future MLCC technology. For targeting boundary-technology areas between existing powder-based tape casting and advanced thin-film process, we have developed a novel powder-sintering thin film process using BaTiO3 nanocrystals to obtain a highly densified microstructure containing columnar-like grains at lower temperatures. Furthermore, the controllability of crystallographic orientations of thin films by solid phase epitaxy has been demonstrated.

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Barium titanate (BTO) particles in the size range from 10 nm to 150 nm have been developed using hydrothermal synthesis with the control range of 10nm. The particles have an optimized morphology and narrow particle size distribution, both of which seems to be contributed to the dispersion of the green sheets in the multi-layer ceramic chip capacitors (MLCCs) that contain these particles. Although these nano-sized BTO are not still spread into the market, it is considered that these are used for the dielectric thin films, the PDF devices, and the piezoelectric devices. The powder properties intend to be improved to optimized with maintaining the advantages of the nano-size and dispersion.

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Nanocrystals are positioned in the intermediate phase between single molecules and bulk crystals. They are expected to be novel nanomaterials, which would show interesting optical and magnetic properties based on confinement size effects and as well as other factors. Recently, we have demonstrated that the reprecipitation method can easily fabricate organic nanocrystals from the solutions in their nonsolvents. We have, thus, discovered interesting size-dependant optical properties of organic nanocrystals compared with those of semiconductors or metals. In this presentation, we will introduce our fabrication technique of organic nanocrystals and their application development.

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ZnO-based elements have attracted many attentions as gas sensor because of their chemical sensitivity to volatile and other radical gases. Considering the application of ZnO film in optoelectronic nanodevices, fabrication ZnO nanoarrays on a large substrate surface by low-temperature and low cost process are of prime importance in future applications. In the present study, a catalyst-free, novel technique was addressed to fabricate ZnO nanoarrays film without any high temperature treatment by the electrodeless chemical deposition at below 100 ^oC. The in situ forced hydrolysis of low-solubility zinc salts to ZnO crystal at the initial stage promoted growth of ZnO nanoarrays by heterogeneous nucleation. The formation mechanism of 1D ZnO nanoarrays and forced hydrolysis of a zinc salts template layer were investigated in a wide range of temperatures and concentrations.

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The surface of BaTiO₃ particles were modified by 3-glycidoxypropyltrimethoxysilane (GPTMS) in various solvents and under various temperature for tuning the surface properties towards their application to epoxy-polymer composites. The solvents and the temperature during the modification process affected to the reacted amount and the reacted structure of GPTMS on BaTiO₃ particles. The relationships among the surface modification conditions, surface structure of BaTiO₃ particles and the dielectric properties of epoxy composite materials were discussed based on the surface characterization by FT-IR, FT-nIR and organic element analysis and dielectric measurements of composite materials.

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Nano particles are synthesized by gas phase and liquid phase, but nano particle are likely to be agglomerated. So it is necessary to disperse it for giving property of nano particles. In case of applying conventional beads mill, it is difficult to disperse agglomerated nano particles to nano particles because of using more than 0.3mm beads. Now we are realized nano particles dispersing by developing the beads mill which can use the small beads (Beads diameter 0.015~0.1mm) for the first time in the world. I will show you the good results gotten by using our machine.

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