Photoluminescence and thermoluminescence properties of Pr~(3+) doped ZnTa2O6 phosphor

摘要

A new red long afterglow ZnTa2O6 : Pr~(3+) phosphor was prepared by solid state reaction at 1200 °C. An ortho-rhombic single phase was obtained, as identified by X-ray diffraction (XRD). The scanning electron microscopy (SEM) images showed that particles were spherical and the crystallite sizes were calculated to be 270 nm using Scherrer's equation. Both blue and red emissions were obtained from the ZnTa2O6 : Pr~(3+) powder. The blue spectral line from the ~3P0 → ~3H4 transition was observed at 448 nm and the more prominent red spectral lines were observed at 608,619 and 639 nm from the ~1D2→ ~3H4,~3P0 → ~3H6 and ~3P0 → ~3F2 transitions, respectively. The main absorption occurred at 259 nm (4.6 eV). This was confirmed to be due to band to band excitation. The energy band gap (E_g) was calculated to be 4.43 ± 0.02 eV. The phosphorescence decay characteristics were measured and the decay times and the depth of the electron trapping centers were calculated.