Recent innovative research and development of high performance thermoelectric materials for power generation in the temperature range from room temperature up to 1300K has been investigated. The concept of guiding principle for the enhancement of thermoelectric performance was briefly summarized including PGEC materials and independent control of the structure and function. In this paper as some of the promising materials, modified Bi-Te system, (filled) Skutterudites, clathrates and layered oxides were discussed.

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Thermoelectric Properties of Ge/Au and Si/Au thin films have been measured as functions of Au concentration and annealing cycles. Ge/Au and Si/Au thin films were prepared by the alternating deposition of Ge or Si and Au in the ultra-high vacuum chamber. In the Ge/Au thin films, the annealing cycles dependence of electrical resistivity decreases as Au concentration increases. The Ge/Au thin films both of 0 and 5 mass % Au have large thermoelectric power. High Au concentration samples are recrystallized even in the heating phase of 1st annealing cycle. From the difference of the atomic radius, Au should be the origin of amorphous phase. The best condition for high thermoelectric properties must be in low Au concentration. For the electrical resistivity of Si/Au thin films, there are almost no dependence of the annealing cycles. Au mainly plays the role of carrier source for the change of the electrical resistivity with Au concentration. We can conclude that the mechanism of the anomalously large thermoelectric power of Si-Ge-Au thin films comes out from the amorphous phase of Si and Ge.

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The p-type Ag_0.208Sb_0.275Te_0.517 boule was unidirectionally grown using a Bridgman furnace and, it was subsequently cooled rapidly by an Ar flush to form a high temperature phase AgSbTe2, which could be desirable for power generation. Though the boule looked a homogeneous Widmannstätten structure of the AgSbTe₂ phase, XRD patterns revealed that some precipitates of Ag₂Te and Sb₂Te₃ were contained in the boule and increased in volume in the growth direction. The relationship between the transformation and the thermoelectric properties was investigated. Figure-of-merit Z of the p-type Ag_0.208Sb_0.275Te_0.517 boule has been evaluated in the temperature range from 300 to 700 K. The maximum figure-of-merit Z_max was different in the portions of the boule. The value of 2.0×10_-3 /K was for the former half portion of the boule at 620 K and that of 1.7×10_-3 /K was for the latter half portion at 585 K . The Ag_0.208Sb_0.275Te_0.517 boule with less precipitates showed a higher Z at higher temperatures. Possibility of improving thermoelectric properties in Ag-Sb-Te system was pointed out.

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This paper presents the characteristics of the electrode bonding by the solid diffusion-sintering method for Chromium Disilicide thermoelectric elements system. Six candidate metal electrodes were selected and the interface between the electrode and thermoelectric element was observed by EPMA to detect the diffusion layer thickness. Electrical contact resistance for each electrode system was detected with one -probe scanning apparatus, so that Ti, Mo, Ta, and Zr were clarified to be superior in order. It is concluded that the contact resistances for these electrodes are satisfactory to the formation of the high temperature thermoelectric module.

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The thermoelectric properties of Mn and Ni substituted sintered magnetite (Mn_2/3Ni_1/3)_xFe_3-xO₄ were investigated for x=0, 0.4, 0.8 and 1.2 in the temperature range 100-700°C. It was found that the grain boundary didn’t affect the electrical conduction notably in this material. The thermoelectric power factor increased with increasing the temperature for each x, and marked a maximum value of 1.31 μW/K²cm for x=0.4 at 700°C.

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Nitrogen oxide (NO_x) removal is being studied for exhaust-gas treatment by pulsed discharge. A recently developed pulsed-power source using inductive energy-storage was used as the high-voltage generator, which drives corona discharge in a small reactor cell. The whole system is very compact, lightweight, and low-cost. It is possible to be operated with relatively low DC voltage supply at low power level. The ultimate target of this development is on-vehicle application for diesel exhaust-gas treatment. In the results that were obtained, NO and NO₂ removal rate can be increased in N₂ atmosphere with increasing repetition rate and NO removal rate in N₂ atmosphere increases as the input voltage is increased.

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The viewing-angle characteristics of electrooptic switching device based on the helix deformation of a homeotropically aligned ferroelectric liquid crystal have been studied. The viewing angle characteristic has been improved using a new pattern of the electrode in which the direction of the molecular orientation of liquid crystal is distributed under the field.

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Having higher melting temperature than polyethylene, polypropylene has been expected as insulation material for power cable. But isotactic polypropylene used generally is unsuitable as cable insulation because it shows poor flexibility, low breakdown strength due to growing spherulites, and so on. But stereoregular syndiotactic polypropylene (s-PP) newly developed with metallocene catalyst shows quite different properties from i-PP.
  The authors had investigated the basic properties of s-PP and the initial properties as a cable which was manufactured using s-PP insulation, in the previous paper. As the results of this, it was revealed that s-PP had superior thermal and electrical properties to cross-linked polyethylene and the s-PP insulation cable showed satisfactory initial properties. However, in order to apply to an actual cable, the properties must be maintainable over 30 years after construction.
  In this paper, we estimated the long term and remaining properties for s-PP insulation cable.
  A series of experiments on long term properties gave following results.
    (1) S-PP cable shows longer life over 30 years.
    (2) The breakdown strength of s-PP cable after long term experiment equal to 30 years is slightly lower than initial breakdown strength, but it’s sufficient as remaining property.
  Furthermore, water-tree resistivity of s-PP was investigated and it was revealed that s-PP significantly suppressed the water tree propagation compared with XLPE.
  These results suggested that s-PP cable would be available as next generation cable.

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Titanium carbide (TiC) / polyethylene (PE) composites have been prepared with various volume fractions of TiC by a melt blending method. Two types of TiC powder with their different particle diameters, 1.48 μm (TiC-A) and ca.100 μm (TiC-B), were utilized in the present study. The electric resistivities (ρ) of the samples decreased gradually with increasing TiC volume fraction (φ_A); in the case of smaller particle size, the value of ρ at room temperature jumped down in the relatively narrow range of φ_A = 0.39 - 0.42, reaching itself as low as 0.1 Ωcm. Temperature dependencies of ρ were also measured to examine the possible application of the composite to polymer PTC thermistors. The resistivity showed positive temperature dependence and changed abruptly in the tenth order of its magnitude during the melting transition of PE. The electric current-cutoff characteristics of the samples indicated excellent features in the over current response despite their low resistivity values, as compared with those of other PTC materials. In parallel, the mechanism of conductivity of the composite was discussed in terms of the percolation theory.

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A movement simulation of the plasma particles is done by using the super parallel computer GRAPE-6. The plasma diffusion phenomena and the plasma oscillation simulated by GRAPE-6 are corresponded to the theoretical value. GRAPE-6 can calculate Coulomb interaction using 100000 particles 4000 times faster than the Pentium4-1.6GHz CPU.

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