Controlled synthesis of star-shaped zinc oxide particles at low temperatures and their quantum size effect

Shintaro Ueno, Shinobu Fujihara

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Star-shaped ZnO particles were synthesized in aqueous solutions containing zinc salts and ammonia. The relationship between nanostructures and photoluminescence properties of the resultant particles is then discussed considering the quantum size effect in the solid state. Regardless of the kinds of zinc salts (formate, acetate, nitrate, or chloride), the star-shaped ZnO particles were formed by aging of the aqueous solutions at 60 °C under controlling pH in the range of 9-10. According to microscopic observations, the star-shaped ZnO particles consist of many branches, each of which is composed of nano-sized ZnO crystallites of a single-crystalline nature. This unique nanostructure is constructed by the adsorption of Zn(OH) 2 sols on initially nucleated ZnO crystals, followed by oriented transformation into ZnO nanocrystallites. The star-shaped ZnO particles show a strong yellow emission with the ultraviolet irradiation. Both excitation and emission bands of the star-shaped particles are blue-shifted due mainly to the quantum size effect. The smaller ZnO nanocrystallites containing a large amount of defects are spacially separated with each other in the star-shaped particles, which is responsible for the strong broad-band yellow emission due to the confinement effect.

Original languageEnglish
Pages (from-to)338-345
Number of pages8
JournalJournal of Alloys and Compounds
Publication statusPublished - 2012 Nov 15


  • Chemical synthesis
  • Crystal growth
  • Photoluminescence
  • Size effect
  • Zinc oxide

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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