Yoshitsugu Hasegawa

Preparation of Y–Ba–Cu–O Superconducting Thin Films by the Mist Microwave Plasma Decomposition Method

Superconducting thin films of the Y-Ba-Cu-O system were prepared on single crystal MgO(100) substrates by a new technique, the mist microwave plasma decomposition method. The onset and zero resistance temperatures occurred at 85 K and 78 K, respectively, for the as-grown film. The lattice constant c0 estimated from Bragg angles of (00n) planes was 11.69 A.

Intercalation of pyridine and quinoline intoα-zirconium phosphate

The uptake of pyridine and quinoline intoα-zirconium phosphate has been investigated by the batch method. The effect of solvent on the reactions was also studied. Pyridine was taken up from ethanol, chloroform, carbon tetrachloride, ethanol-water, and acetone-water solutions, but not from pure acetone at 25°C. Water accelerated the uptake of pyridine. These facts indicate that a water molecule was involved in the uptake reaction of pyridine.Quinoline was taken up easily in an ethanol-water solution at 25°C, and in an ethanol solution at the boiling point. Two reactions — ion exchange and intercalation — occur on taking up the quinoline. An IR spectrum of the quinoline form is reported.

Optical Characterization of Deep Levels in Single Crystals of CuGaS2 Grown by Chemical Vapor Transport

Optical absorption spectra were measured in undoped and Fe- or Ni-doped single crystals of CuGaS2 grown by the chemical vapor transport technique. Chemical analysis of Fe concentration by absorption spectrophotometry and optical characterization by absorption and photoluminescence(PL) spectroscopy in these materials revealed that the main trace impurities which darken undoped crystals are Ni and Fe. The excitation spectrum of the infrared PL due to Fe3+ was also measured. From this, the 1.8 eV peak of the strong absorption band introduced by trace Fe impurities was interpreted in terms of the transition from the valence band to the dangling bond state hybridized with 3d orbitals.

Synthesis of γ-zirconium phosphate by the fluoro-complex method and the intercalation behavior of some α-diimines

The ammonium form of γ-zirconium phosphate has been synthesized by the direct precipitation method from fluorozirconate solution in the presence of ammonium dihydrogen phosphate. The hydrogen form Zr(HPO4)2 · 2H2O, was obtained by acid treatment of the ammonium form α-Zirconium phosphate , Zr(HPO4)2 · H2O, with a relatively large particle size resulted from fluorozirconate solution in the presence of concentrated orthophosphoric acid. The intercalation behavior of such α-diimines as 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) toward γ-zirconium phosphate was investigated, and it was found that about 0.2 mol of bpy and 0.5 mol of phen have been incorporated respectively per one mol of the host, with the expansion of interlayer distances. Further incorporation of Cu(H) ions into the interlayer space of these intercalates was possible. The bpy intercalate took up more Cu(II) ions than γ-zirconium phosphate, indicating that effective pillars are constructed between layers and the ion exchange of Cu(II) ions is facilitated thereby.

Studies on the ammonium form of crystalline zirconium phosphate—I: Ammonium-sodium ion exchange isotherms

The isotherms for NH4+/Na+ exchange on crystalline zirconium phosphate have been investigated at 25°C. The isotherms obtained show a hysteresis loop. When sodium ion replaces the ammonium ion in the exchanger, the exchange proceeds in two steps. First the formation of the intermediate phase is observed, and subsequently this is converted to the sodium form. As the two steps take place for the very close mole fractions of sodium ion in the solution, the process is observed as a single one. When ammonium ion replaces the sodium ion in the exchanger the sodium form is converted into the ammonium form directly.

Intercalation of porphyrin (TMPyP) and copper-porphyrin into γ-zirconium phosphate

Water-soluble α,β,γ,δ-tetrakis(4-N-methylpyridyl)porphine(TMPyP) was directly intercalated into γ-zirconium phosphate (γ-ZrP) with expansion of the interlayer distance from 12.3 to a maximum of 17.2 Å, indicating parallel orientation of porphyrin to the layer of γ-ZrP. Diffuse reflectance spectra of the intercalate shows that the porphyrin is protonated in the interlayer space. Uptake of Cu2+ ions into the porphyrin intercalate takes place with further increase in the interlayer distance. It was observed that TMPyP metalated Cu2+ in γ-ZrP. Copper porphyrin can also be taken up quite easily and an interlayer spacing of 18.6 Å is attained.

Direct and stepwise intercalation of alkylalcohols intoα-zirconium phosphate

Intercalation of alkylalcohols into α-zirconium phosphate was investigated at 25°C and/or under reflux.n-Alcohols having two to five carbons and 2-propanol were taken up at 25°C. These alcohols, andn-hexanol and heptanol, also intercalated under reflux.n-Alcohols having eight to eighteen carbon atoms intercalated when a stepwise method was employed. 2-Butanol and tertiary amylalcohols intercalated under reflux using a butanol intercalate as a starting material. Ethanol-to-butanol intercalates were unstable at room temperature, losing alcohols and changing to α-zirconium phosphate. The particle size of the α-zirconium phosphate did not affect the intercalation of alcohols.

Intercalation of phenylethylamines intoα-zirconium phosphate and characterization of intercalates

The intercalation of phenylethylamines intoα-zirconium phosphate has been investigated by the pH titration method.dl-1-Phenylethylamine (dl-PEA) is taken up in two stages. New phases were obtained: Zr(HPO4)2(dl-PEA) · H2O in the first, and Zr(HPO4)2(dl-PEA)/43· H2O in the second stage. 2-Phenylethylamine (2-PEA) also is loaded in two stages, but the first end point is not observed clearly. A new phase, Zr(HPO4)2(2-PEA)2 · H2O has been formed at the second stage. The new phases have been characterized by elemental analysis, X-ray diffractometry, thermal analysis and IR spectroscopy.

Intercalation of N, N-dimethyl-1-phenylethylamine into α-Zirconium Phosphate

The intercalation and deintercalation of N, N-dimethyl-1-phenylethylamine (N,N-amine) into α-zirconium phosphate was investigated by pH titration. N,N-amine was taken up easily in one step to give a new phaseZr(HPO4)(HPO4·N,N-amine) · H2O, which was characterized by X-ray diffractometry, IR spectroscopy, and thermal analysis. Therelease of N,N-amine from the solid was found to be irreversible due to structural changes in both the intercalation and deintercalation reactions.

Intercalation of n-Alkylamines and n-Alkyldiamines into γ-Zirconium Phenylphosphonate Phosphate

Crystalline γ-zirconium phenylphosphonate phosphate was prepared according to Yamanakas method and the intercalation behavior of n-alkylamines and n-alkyldiamines were investigated. In the case of n-alkylamines, a linear increase in interlayer distance was observed up to a carbon atom number of 12, whereas in n-alkyldiamines, only two di-amines, ethylenediamine and propylenediamine, were intercalated with respective increases in the interlayer distance. The increment of interlayer distance in both monoamines and diamines indicates the formation of a monomolecular layer in the interlayer region of the host, in contrast to the case in γ-zirconium phosphate as a host.