Sol–gel preparation and photoluminescence properties of tetragonal ZrO2:Y3+, Eu3+ nanophosphors

By controlling Eu3+ doping concentration, ZrO2:Y3+, Eu3+ (YSZ:Eu) nanophosphors with tetragonal structure have been prepared by sol–gel method. The properties of the resulting phosphors are characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), photoluminescence (PL) spectra and decay curve. The excitation spectra of YSZ:Eu phosphors are mainly attributed to O2- → Eu3+ charge-transfer (CT) band at about 254 nm and some sharp lines of Eu3+ f–f transitions in near-UV region with one strong peak at 395 nm. The emission spectra were used to probe the local environments of Eu3+ ion in ZrO2 crystal. Based on the high-resolution emission and excitation spectra at 10 K, it is identified that the lattice site of Eu3+ in tetragonal ZrO2 nanocrystals descending from D4h to approximate C2V as a result of the lattice distortion. Under the 395 nm excitation, intense red emission peaked at 607 nm corresponding to 5D0 → 7F2 transition of Eu3+ is observed for 6 at.% YSZ:Eu phosphors as the optimal doping concentration. The luminescence properties suggest that YSZ:Eu phosphor may be regarded as a potential red phosphor candidate for near-UV light emitting diodes (LEDs).

► YSZ:Eu nanophosphors with pure tetragonal have been prepared by sol–gel method.
► The Eu3+ ions should occupy C2V Site in YSZ:Eu phosphors.
► There exist excitation peaks from non-ground state of 7F1 and 7F2 at 298 K.