Polyvinyl Alcohol Substrate Research Articles

318 Ni_2MnGa スパッタ膜の形状記憶効果

The Ni-Mn-Ga films were deposited on a poly-vinyl alcohol substrate with a radio-frequency magnetron sputtering apparatus using Ni_<50>Mn_<25>Ga_<25> and Ni_<52>Ga_<24> targets. After separating from the substrates, the films were annealed at several temperatures for 3.6ks. The chemical composition of the films depended on the radio-frequency generating power, however, there was no dependence on the heat treatment temperature. Each deposited film has a columnar grain structure. After heat treatment, the width of columnar grains widened and then became indistinct with increasing heat treatment temperature. At more than 1073 K, the precipitation of MnO was observed clearly. The films showed he most crystallinity at 1073 K. The martensitic transformation temperature increased with increasing nickel content of films, while the Curie temperature decreased. The film obtained at 200 W using the Ni_<52>Mn_<24>Ga_<24> target after heat treatment at 1073 K showed one-way shape memory effect through the reverse martensitic structural transformation during heating.

Interfacial Molecular Interactions Between Ferroelectric Liquid Crystal and Polyvinylalcohol Films as Probed by Infrared Reflection Absorption Spectroscopy

Abstract Infrared reflection absorption spectroscopy (IRAS) was used to study the molecular alignment of the ferroelectric liquid crystal material, (S)-4-(α-methylheptyloxy)-4′-(4″-n-octylphenyl-oxycarbonyl)biphenyl (MHOPOB), on a highly-purity polyvinylalcohol (PVA) film. The molecular alignment was characterized as a function of the temperature and the thickness of the liquid crystal. For the film of 200nm in thickness, the molecules in the chiral smectic C phase (SmC*) were aligned with their long axes perpendicular rather than parallel with respect to the PVA substrate surface. This alignment was found to disappear at the isotropic phase temperature. A similar molecular alignment was observed for a 20nm-thick MHOPOB film in the SmC* phase, but the detailed alignment was different from that in the 200nm-thick film. This alignment in the SmC* phase was sustained even at the isotropic temperature in contrast to the 200nm-thick film, suggesting a short-range interaction between the PVA film surface and MH...