The geometrical effects of Bi and Bi_0.88Sb_0.12 poly-crystals on the cooling temperature were investigated at room temperature for a magneto-Peltier (MP) device and a combined magneto-Peltier and Ettingshausen (MP-EH) device, which are not in contact with a heat sink. The magnetic field is applied parallel and perpendicular to the thickness t and width W of each sample, respectively, and the temperature gradient is generated along the length L by flowing an electrical current. The maximum cooling temperature at the cooled surface of both devices was measured without and with the magnetic field for various samples of different dimensions. As a result, it was found that in a combined MP-EH device the cooling temperature is very sensitive to the geometrical shape of the cross-section (W × t) of a thermoelement, while in an MP device it depends significantly on the size of the cross-sectional area rather than the geometrical shape. The largest cooling temperature was achieved in an MP device when the thermoelement had an optimum cross-sectional area in which the Joule heating and the thermal conduction energies became equal. The cooling temperature of an MP device consisting of Bi_0.88Sb_0.12 with optimum dimensions slightly exceeded the cooling temperature of 5.7 K which was obtained for an ordinary p-type Bi₂Te₃.

抄録全体を表示

Recently, PET bottles have been widely used because of their convenient lightness. Recycling of discarded PET bottles is therefore desirable. Raw materials such as fiber and resin can be regenerated from them. Electromagnetic wave absorbers were produced using a porous board made of polyester fibers recycled from PET bottles. Its loss factor was a composite of carbon and various ferrites such as Mn-Zn ferrite, Ni-Cu-Zn ferrite, and magnetite. The bulk specific gravity of these absorbers is very low (less than 1.2). These absorption characteristics are practical for Blue Tooth and ETC frequencies (2.45 GHz and 5.8 GHz, respectively).

抄録全体を表示

The unidirectional anisotropy of exchange-coupled Ni₈₁Fe₁₉/Co₉₀Fe₁₀/Cr_45.5Mn_45.5Pt₉ films was found to amount to ∼0.345 erg/cm² when they were subjected to the following process: (a) an NiO-capped layer was sputter-deposited onto the CrMnPt film, (b) subsequently the films were annealed at 230°C for 3 h, and (c) finally the NiO-capped layer was eliminated by Ar ion-milling. The above anisotropy value was comparable with that of ferromagnet/Pt₅₀Mn₅₀ films. Furthermore, the strong unidirectional anisotropy is thought to be caused by the facts that large stress relief of the NiO-capped layer through thermal annealing acts to enlarge the c/a ratio within CrMnPt (a and c are lattice parameters), inducing a so-called stress-induced anisotropy within CrMnPt.

抄録全体を表示