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 (TL). Zr(1−x)Pr x O2 (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 and 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 λ ex = 300 nm and λ em = 612 nm. The TL 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. The TL emission measured at 695 K confirms that Pr3+ replaces Zr4+ in cubic lattice sites of ZrO2. This work shows the relationship between the luminescence properties and different structures of ZrO2 and that supports the design of new materials for possible applications.