Itaru Fujimura

Development of (Pb, Nb)(Zr, Sn, Ti)O3 Film Using a Sol-Gel Process and Resulting Antiferroelectric Properties

(Pb, Nb)(Zr, Sn, Ti)O3 films are developed on Pt-coated Si substrates using a sol-gel process and their electronic properties are studied. An excessive amount of Pb in precursor solution is necessary to obtain films with good crystallinity. A 2.4-µm-thick film annealed at 650°C shows a dielectric constant of about 400 at room temperature. Electric field intensity at the antiferroelectric-to-ferroelectric phase transition is 80 kV/cm. Spontaneous polarization is 28 µC/cm2. Spontaneous polarization in this film is close to that observed in bulk samples (sintered at 1270°C). The electric field intensity, however, is approximately twice that of bulk samples.

Purification of Head-to-Tail-Type Regioregular Poly(3-hexylthiophene), HT-P3HexTh, and Investigation of the Effects of Polymer Purity on the Performance of Organic Field-Effect Transistors

Analytically pure head-to-tail-type poly(3-hexylthiophene-2,5-diyl), HT-P3HexTh, has been obtained by the slow reprecipitation of the polymer. A FET made of purified HT-P3HexTh yielded a typical FET I–V curve with saturation and showed a five fold higher FET mobility than that of conventionally used HT-P3HexTh.

Optical Studies of Ba4+xNa2-xNb10-xTixO30 Crystals

Crystals of Ba4+xNa2-xNb10-xTixO30 (x<0.8) were pulled from the melts and their optical and dielectric properties were examined. They were all biaxial, though the orthorhombic-to-tetragonal transition point was lowered with Ti substitution. The birefringence nb-na was so small that any detwinning procedure seemed unnecessary. The figure of merit for electrooptical performance was larger than that of Ba2NaNb5O15. An analysis of the observed results in birefringences and half-wave voltages was performed in comparison with a phenomenological calculation based on the spontaneous Kerr effect.