Effect of Pr doping on structure and luminescence properties of ZrO₂ nanoparticles

Abstract

Pr3+ impurity transitions in monoclinic and cubic phases of ZrO2 have been investigated by photoluminescence and thermoluminescence. Zr(1− x)PrxO2(0 ≤ x ≥ 0.015) samples were prepared by the combustion method. Rietveld refined x-ray diffraction results confirm that undoped ZrO2 has a monoclinic structure whereas Pr doped ZrO2 samples are in mixed phase consisting of monoclinic and cubic structures. ZrO2 shows a broad defect-related emission peak centered at 500 nm under an excitation wavelength of 300 nm. A series of Pr3+ -related emissions are observed at 512, 584, 612-640 nm due to 3P0→3H4, 3P1+1I6→3H5, 1D2→3H4 transitions and between 719-740 nm due to 1D2→3H5 transitions when excited with 454 nm. The PL decay lifetime of Zr0.996Pr0.004O2 is 1.55 μs for fixed λex = 300 nm and λem = 612 nm. The thermoluminescence glow curve of Zr0.99Pr0.01O2 shows a prominent peak at 695 K and secondary peaks at 508 K and 570 K which are not observed in undoped ZrO2. TL emission measured at 695 K confirm that Pr3+ replaces Zr4+ in cubic lattice sites of ZrO2. This work shows the relationship between luminescence properties and different structures of ZrO2 and that supports to design of new materials for possible applications.