Evidence of luminescence modification with structure of zirconia phases

Three crystallographic phases of nanocrystalline zirconium oxide (ZrO2) are prepared by solution combustion technique. Tetragonal and cubic phases are stabilized at low temperature by adding yttrium content. Phase stabilization is confirmed by X-ray diffraction and Raman spectroscopy. The XRD results are analyzed using rietveld refinement and average crystallite size is found to be 50−60 nm. Characteristic PL emission of Dy3+ ions are observed at 490, 578, 672 and 764 nm corresponding to 44F9/2→6H15/, 4F9/2→6H13/2, 4F9/2→6H11/2 and 4F9/2→6H9/2 transitions respectively. The spectral peak shape changes and variation of blue to yellow intensity ratio in different symmetry of ZrO2 has been discussed. CIE chromaticity color coordinates (x, y) are calculated for Dy3+ doped zirconia phosphors and fall near white light region. A high intense TL glow peak at 441 K and a less intense peak at 550 K are observed in monoclinic ZrO2. The intensity of 441 K TL glow peak is drastically reduced and a new TL peak at 703 K is found in tetragonal ZrO2. Whereas, cubic ZrO2 exhibit a single TL glow with peak at 703 K. Dy3+ doped ZrO2 (monoclinic) exhibit two prominent TL peaks at 457 and 695 K whereas tetragonal and cubic samples shows only high temperature peak. It is concluded that TL curve is modified in three zirconia system and TL kinetic parameters are discussed.