Laser-stimulated luminescence of yttria-stabilized cubic zirconia crystals

Abstract

The kinetics of laser-stimulated luminescence (LSL) of yttria-stabilized cubic zirconia single crystals is investigated. Excitation of ZrO2⋅9.5%Y2O3(100) and (110) using ns pulses of 213 nm (5.82 eV), 266 nm (4.66 eV), and 355 nm (3.49 eV) photons produce LSL bands with Gaussian profiles and peak maxima at 460 nm (2.69 eV), 550 nm (2.25 eV), and 600 nm (2.07 eV), respectively. LSL involves a single-photon process for energy densities below ∼1.0 MW/cm2. Decay times vary from 0.1 to 100 μs depending on the excitation energy and temperature. Decay kinetics are hyperbolic indicating that all LSL bands result from recombination. The LSL quenches with increasing temperature and activation energies obtained using the Mott approximation are 0.10±0.01, 0.20±0.02, and 0.45±0.04 eV for the 2.69, 2.25, and 2.07 eV LSL bands, respectively. The various activation energies, decay kinetics, and excitation/emission energies correspond to the presence of several emission centers which can be associated with anion vacancies. We tentatively assign these to intrinsic F centers and extrinsic F-type centers. The latter are associated with one and two Y3+ ions in the nearest neighborhood positions. Since the normalized temperature dependencies of the decay coefficients are similar for all the LSL bands, we suggest that recombination primarily involves electrons, trapped at intrinsic and extrinsic defect sites, and mobilized holes.

Structural and optical properties of europium doped zirconia single crystals fibers grown by laser floating zone

“…Broad unstructured deep level recombination in the yellow/orange spectral region has been observed in the different ZrO 2 polymorphs and assigned to F-type defects, involving the oxygen vacancy and their complexes. [35][36][37][38] Overlapped with the F-type emission band, the as-grown cubic stabilized ZrO 2 fibers show an additional emission in the red region with pronounced maxima at 614 nm ͑2.02 eV͒ and 641 nm ͑1.93 eV͒. These maxima were previously observed in polycrystalline YSZ and were attributed to the intraionic recombination of a lanthanide ion present as a contaminant in the samples.…”

Photoluminescence of sol–gel-prepared hafnia

“…The broadband emission centered at 4.4 eV observed in high-quality crystalline material has been ascribed to self-trapped excitons [6], whereas the origin of lowerenergy bands is still unclear although the various intrinsic or extrinsic defects (especially oxygen vacancies) are the most probable cause [12]. This is also supported by the observation that the UV-excited emission of nanocrystalline zirconia is sensitive to the oxygen content in the ambient [13,14].…”

Photoluminescence properties of scandia-stabilized zirconia

“…Nevertheless, the rise of intensity of the peak at 2.22 eV in the present study has another possibility against the previous assignment [2]; the peak at 2.53 eV for the unperturbed vacancy (F-type) and the peak at 2.22 eV for the perturbed vacancy (F A -type). The previous assignment was based on a report for the undoped zirconia which claimed 2.69 eV as PL peak energy for vacancy state [5], and suggested that the same type of vacancy also has a PL peak at around 2.5 eV [6]. However, we still prefer our choice above when we take the results for Sc-and In-8YSZ [3] into consideration.…”

“…3. Judging from the fact that undoped zirconia yields the peak of 2.69 eV and the addition of scandium or indium oxide both results in emergence of the peak at 2.70 eV, the doping of Sc 3+ , and probably In 3+ also, may induce photo-excitation to the conduction band, because the peak at 2.69 eV is for the recombination of photo-excited carrier at conduction band with hole in unperturbed oxygen vacancy state [5]. The temperature dependence observed in Fig.…”

“…Once the carrier is excited, the radiative recombination probability is affected by non-radiative recombination loss, which is determined by thermal property of the excited state [5]: …”