Eu3+-Doped Wide Band Gap Zn2SnO4 Semiconductor Nanoparticles: Structure and Luminescence
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文摘
Nanocrystalline Zn2SnO4 powders doped with Eup>3+p> ions were synthesized via a mechanochemical solid-state reaction method followed by postannealing in air at 1200 °C. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Raman and photoluminescence (PL) spectroscopies provide convincing evidence for the incorporation of Eup>3+p> ions into the host matrix on noncentrosymmetric sites of the cubic inverse spinel lattice. Microstructural analysis shows that the crystalline grain size decreases with the addition of Eup>3+p>. Formation of a nanocrystalline Eu2Sn2O7 secondary phase is also observed. Luminescence spectra of Eup>3+p>-doped samples show several emissions, including narrow-band magnetic dipole emission at 595 nm and electric dipole emission at 615 nm of the Eup>3+p> ions. Excitation spectra and lifetime measurements suggest that Eup>3+p> ions are incorporated at only one symmetry site. According to the crystal field theory, it is assumed that Eup>3+p> ions participate at octahedral sites of Znp>2+p> or Snp>4+p> under a weak crystal field, rather than at the tetrahedral sites of Znp>2+p>, because of the high octahedral stabilization energy for Eup>3+p>. Activation of symmetry forbidden (IR-active and silent) modes is observed in the Raman scattering spectra of both pure and doped samples, indicating a disorder of the cation sublattice of Zn2SnO4 nanocrystallites. These results were further supported by the first principle lattice dynamics calculations. The spinel-type Zn2SnO4 shows effectiveness in hosting Eup>3+p> ions, which could be used as a prospective green/red emitter. This work also illustrates how sustainable and simple preparation methods could be used for effective engineering of material properties.

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