Luminescent dynamics of Pr3+ in MTaO4 hosts (M=Y, La or Gd)

Luminescence characteristics including fluorescence, phosphorescence, and thermoluminescence of Pr3+ in orthotantalate host matrices are presented. X-ray diffraction (XRD) spectra indicate that MTaO4:Pr3+ (M=Gd, Ta and Y) phosphor materials were successfully prepared at 1200 °C using the solid state reaction method. Red and blue–green emissions were observed from the three phosphors when they were characterised using the DESY synchrotron radiation. A simplified energy transfer scheme explaining energy transfer from the TaO4 group to either Gd3+ states in the GdTaO4:Pr3+ system or directly to Pr3+ states in LaTaO4:Pr3+ and YTaO4:Pr3+ systems is presented. Afterglow measurements were carried out after UV exposure at room temperature and the phosphorescence decay curves suggest multi-exponential decay behaviour consisting of the slow and fast components following the order; GdTaO4:Pr3+