Tailoring the morphology and structure of nanosized Zn2SiO 4: Mn2+ phosphors using the hydrothermal method and their luminescence properties

Jae Sul An, Jun Hong Noh, In Sun Cho, Hee Suk Roh, Jin Young Kim, Hyun Soo Han, Kug Sun Hong

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Mn2+-doped Zn2SiO4 phosphors with nanoellipsoid or nanowire morphologies were synthesized at low temperature <200 °C by a hydrothermal method without any surfactants. The morphologies of the phosphors were easily tailored by varying the amount of hydroxide ions in the precursor solution before the hydrothermal reaction. Absolute ethanol was used as a solvent instead of distilled water to explore the effects of hydroxide ions on the morphology and crystal structure. We adjusted the amount of hydroxide ions by changing the pH of the precursor solution. Sheaves of powders with an ellipsoid shape were synthesized at low pH values of 7 and 9, at which only a few hydroxide ions were present, whereas powders with a nanowire shape were produced at a high pH of 11, at which many hydroxide ions were present. In addition to its morphology, the hydroxide ions also affect the crystal structure of the synthesized powder. Whereas a Zn2SiO 4 phase with a willemite structure was formed at pH 7 and 9, a Zn4Si2O7(OH)2•H2O phase with a hemimorphite structure was formed at pH 11. The as-prepared powders with a willemite structure showed an intense green emission (λ ≈ 525 nm) under 254 nm excitation, whereas the as-prepared powders with a hemimorphite structure did not show any emission. However, all of the powders showed a willemite structure while retaining their original shape after annealing at 900 °C under a reducing atmosphere. The annealed sheaves of willemite with an ellipsoid shape showed a more intense green emission with a longer decay time than the phase-transformed willemite nanowires. These results were discussed in terms of the surface defects and dopant concentration.

Original languageEnglish
Pages (from-to)10330-10335
Number of pages6
JournalJournal of Physical Chemistry C
Volume114
Issue number23
DOIs
Publication statusPublished - 2010 Jun 17
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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