Luminescence of oxygen related defects in zirconia nanocrystals

Abstract

The luminescence of undoped tetragonal structure ZrO 2 nanocrystals was studied. The luminescence intensity depends on oxygen content in gases mixture in which the nanocrystals were annealed. The distorted Zr-O bond is suggested to be the recombination center for band carriers. The oxygen deficient defect is proposed to be responsible for photoluminescence.

Bioinertness and fracture toughness evaluation of the monoclinic zirconia surface film of Oxinium™ femoral head by Raman and cathodoluminescence spectroscopy

“…1(b) also shows a deconvolution into sub-band components of Gaussian nature from the overall cathodoluminescence spectrum. General observations of luminescence emission from zirconia materials, as found in the literature (Li et al, 1993;Petrik et al, 1999;Smits et al, 2007;Yueh and Cox, 2003), consistently report a broad emission band (peaking at around 500 nm) conspicuously independent of lattice polymorphism, which well agrees with what is found in the present investigation. Embedded in such a broad emission spectrum, obtained from the top surface of the as-received hip component, six partly overlapping sub-band could be deconvoluted.…”

“…2(a) and (b), respectively. Since the cathodoluminescence intensity is inversely proportional to oxygen vacancy concentration (Smits et al, 2007;Yueh and Cox, 2003) and, thus, directly proportional to local oxygen content, the overall intensity profile along the oxide scale suggests that the surface of Oxinium™ is closer to oxygen stoichiometry than its immediate (zo3 mm) subsurface. A vacancy-rich zone was found in the immediate sample subsurface down to about 3 mm in depth, followed by a gradual stoichiometry recovery down to a depth of about 6 mm.…”

“…1(b) shows a typical cathodoluminescence spectrum obtained from the surface of the Oxinium™ femoral head. One peculiarity of the cathodoluminescence emission of zirconia resides in the fact that its intensity increases with decreasing concentration of oxygen vacancies (Smits et al, 2007;Yueh and Cox, 2003). Vacancy annihilation leads to an increase in CL intensity since producing an increase in Zr-O bond stretching (i.e., as a consequence of oxygen overcrowding), which in turn enables a more efficient emission as compared to oxygen vacancy sites themselves.…”

Oxygen defects-modulated green photoluminescence of Tb-doped ZrO2 nanofibers

“…For the sample annealed at 500°C, there were two broad peaks at around 410 and 520 nm attributed to the PL of ZrO 2 intrinsic defects ͑related to oxygen vacancies͒. 9,10 In addition, there were four emission peaks at about 488, 543, 584, and 620 nm corresponding to the intra-5 D 4 → 7 F j ͑j =6,5,4,3͒ transitions of Tb 3+ ions. The strongest emission peak at 543 nm is responsible for the characteristic green light emission of 5 D 4 → 7 F 5 transition.…”

“…This is because that annealing the samples in air at higher temperature ͑600-800°C͒ reduces the oxygen vacancies concentration, leading to the quenching of the intrinsic defects luminescence. 10 Moreover, the PL intensities related to Tb 3+ decreased monotonously with the quenching of the intrinsic defects luminescence, implying that the defects states could be sensitizers in ZrO 2 : Tb nanofibers.…”