Luminescence properties of Ce-doped ZrO 2 phosphors synthesized by combustion method.

Zr 1-x Ce x O 2 with x = 0.005, 0.01, 0.02, and 0.03 samples were synthesized using a combustion technique. The X-ray diffraction results revealed that Ce-doped ZrO 2 nanoparticles were in a monoclinic structure up to 1 mol% Ce concentration. The increase in the Ce concentration caused more distortion in the monoclinic structure of zirconia. The samples showed a mixed phase (monoclinic + tetragonal) beyond 1 mol% Ce content. The crystallite size (D) and strain (ε) were calculated from the Williamson-Hall equation. The D decreased from 25 ± 1 to 20 ± 1 nm and ε increased from 0.03 to 0.28% with an increase in Ce concentration. Photoluminescence (PL) spectra of Zr 1-x Ce x O 2 showed emission in the blue region under an excitation wavelength of 290 nm. Zr 0.995 Ce 0.005 O 2 showed the highest PL intensity with an average lifetime of 0.93 μs, and the PL intensity decreased with the increase in the Ce concentration. Thermoluminescence (TL) glow curves of Zr 1-x Ce x O 2 were measured after gamma irradiation (500 Gy) with a heating rate of 5 K s -1 . The TL curve of Zr 0.995 Ce 0.005 O 2 showed two prominent peaks at 412 K (peak 1) and 600 K (peak 2). The first TL glow peak was shifted towards a higher temperature at 440 K above 1 mol% Ce concentration. Repetitive TL measurements on the same aliquot exhibited excellent repeatability. Kinetic parameters associated with the TL peaks were calculated using the curve fitting method. Peak 1 followed non-first-order kinetics. The value of the activation energy of the 440 K peak was found to be 0.95 ± 0.01 eV for Zr 0.99 Ce 0.01 O 2 . These findings showed that Zr 1-x Ce x O 2 might be used in lighting and radiation dosimeter applications.