Photoluminescence and defect centers in near violet emitting Pb2+doped CaYAl3O7 phosphors obtained by urea-nitrate auto combustion synthesis

A series of CaYAl3O7 phosphors doped with different concentrations of Pb2+ were prepared by an auto solution combustion route. The structure, luminescence, and electron paramagnetic resonance (EPR) spectra were ana-lysed. The X-ray diffraction (XRD) patterns identify the tetragonal phase formation of CaYAl3O7 with a crystallite size in a range of 37-42 nm. The scanning electron microscope (SEM) images were captured to study the surface morphology of the prepared samples. The emission spectra for the prepared phosphors exhibit a wide emission band centered at 362 nm under 270 nm excitation. Un-doped and Pb2+ doped CaYAl3O7 phosphor exhibit an EPR spectrum which arises from two noticeable defect centers. Center I with a g-value equal to 1.96 and a relatively broad line width is temporarily defined to an F+ -center (an electron trapped at an anion vacancy). Center II with g = 2.0 is also ascribed to an F+ -center.

Automated summary

In this study, a series of CaYAl3O7 phosphors doped with different concentrations of Pb2+ were synthesized using an auto solution combustion route. The structure, luminescence, and electron paramagnetic resonance (EPR) spectra of the phosphors were analyzed. XRD patterns confirmed the formation of tetragonal phase CaYAl3O7 with a crystallite size ranging from 37 to 42 nm. SEM images revealed the surface morphology of the prepared samples. The emission spectra showed a wide emission band centered at 362 nm under 270 nm excitation for the phosphors. The EPR spectra of both undoped and Pb2+-doped CaYAl3O7 phosphors exhibited distinct defect centers, namely F+ -centers, with different g-values.