江戸後期の渡来唐桟布(とうざんふ)に用いられた橙色染色剤・Pb₂CrO₅ の微細構造

抄録

  The nanostructure of the orange dye compound Pb₂CrO₅ in cotton fiber used for touzan fabric imported in the late Edo period has been investigated. Dyed fibers are taken from old touzan fabric. To observe the distribution of nanometer-sized compound grains in the fiber, the cross section of the fiber is flattened by ion milling after mechanical polishing. The nanostructure is observed by SEM and TEM. The composition and crystal structure are analyzed by EDS, XRD and ED. The dye compound Pb₂CrO₅, is mainly detected by EDS and XRD. Fine acicular precipitates of Pb₂CrO₅ are aligned along the fiber, forming concentric circles. The Pb₂CrO₅ crystals have lengths and widths of 50-100 nm and 20-50 nm, respectively. Fine rectangular monoclinic PbCrO₄ crystals of 3-5 nm are distributed randomly throughout the fiber. Preferential precipitation is observed at a crack in the fiber, and a precipitation-free zone near the fiber surface is also observed.