Structural and Optical Properties of Tunable Warm‐White Light‐Emitting ZrO 2 :Dy 3+ – Eu 3+ Nanocrystals

A series of Dy 3+ –Eu 3+ ‐codoped ZrO 2 nanocrystals with tetragonal and cubic symmetry was synthesized via a wet chemical reaction. When the Eu 3+ ‐doping content was fixed, the crystal structure could be stabilized from the mixed phase to single cubic phase by simply adjusting the content of Dy 3+ . The cubic ZrO 2 :Dy 3+ –Eu 3+ nanoparticles exhibited spherical and nonagglomerated morphology. The effective phonon energy of cubic ZrO 2 :5%Dy 3+ –5%Eu 3+ was calculated to be 445 cm −1 , which is lower than the previously reported results. Extensive luminescence studies of ZrO 2 :Dy 3+ –Eu 3+ as a function of Dy 3+ content demonstrated that the dopant concentration and its site symmetry play an important role in the emissive properties. Under 352 nm excitation, the increment of Dy 3+ concentration in ZrO 2 :Dy 3+ –Eu 3+ led to an increase in orange (590 nm) and red (610 nm) emissions of Eu 3+ ions, which are attributed to the 5 D 0 → 7 F J ( J  = 1, 2) transitions of Eu 3+ ions. This increment is possibly due to the efficient energy transfer ( ET ) 4 F 9/2 :Dy 3+ → 5 D 0 :Eu 3+ . The phosphors can generates light from yellow through near white and eventually to warm white by properly tuning the concentration of Dy 3+ ions through the ET and change in site symmetry. These phosphors may be promising as warm‐white‐/yellow‐emitting phosphors.