Colour centre production in yttria-stabilized zirconia by X-ray and electron irradiations: effect of yttria content

Abstract

International audienceYttria-stabilized zirconia (YSZ) single crystals (for 9.5 and 18 mol% yttria)were irradiated at room temperature (RT) by X-rays (W white spectrum) and2.5-MeV electrons. The growth curves of the so-called T-centre (for trigonalcentre, i.e. Zr3+ sitting in a trigonal symmetry site) were studied as a functionof absorbed dose, or irradiation time, by UV–visible optical absorption (OA)spectroscopy and X-band electron paramagnetic resonance spectroscopy. Thedefect concentration at saturation and the production rate are increased by afactor around two for 18 mol% yttria with respect to 9.5 mol%. Defect decaywas then followed after irradiation by OA spectroscopy as a function ofageing time at RT. Growth and decay curves of the T-centre are modelled onthe basis of rate equations of charge-exchange reactions with the zirconiumlattice ions. Increase in yttrium content is thought to decrease hole trappingon Zr3+ ions, thereby enhancing T-centre formation

Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria

“…It has to be noted that the latter determinations were based on a crude approximation of the electron-energy dependence of σ d . Besides, the F + /F center concentration ratio might also depend on electronic excitation processes and subsequent back trapping of free holes and electrons [22], as found for electron-irradiated YSZ [34]. Here, we find a branching ratio almost equal to 1 between the two channels.…”

On-line optical absorption of electron-irradiated yttria-stabilized zirconia

“…There is an overall qualitative agreement on the behavior of the absorption bands that can be assigned to the color-center formation by electron irradiation in YSZ. The fitted value of the rise time ( = 10 min) and lifetime (' = 18 min) of the 3.3-eV band for 2.5-MeV electrons [22] are larger than the present results, but they lie in the same range. This means that the recombination processes associated to the decay of the associated optical absorption are quite slow as opposed to the fast decay of transient species such as STEs or some hole centers [28][29].…”

“…However, on a much longer time scale, on-line measurements for 2.5-MeV electron irradiation of YSZ have reported the growth of the 3.3-eV absorption band (375 nm) versus irradiation time up to saturation and sequential time decay after beam shut-off [22]. Both growth and decay data were least-square fitted with exponential rise or decay curves to asymptotic values like in Eqs.…”

“…The kinetics of growth and decay of color centers was also followed as a function of irradiation time for X-ray irradiation and 2.5-MeV electron irradiation by using EPR spectroscopy and on-line UV-visible absorption spectroscopy [22]. The aim of the present study is to extend those results by following the growth and time decay of the on-line UV-visible absorbance of YSZ for various electron energies.…”

Colour centre recovery in yttria-stabilised zirconia: photo-induced versus thermal processes

“…2a). These data can be fit by decay curves versus time to a non-zero asymptotic value, just like for T-centres after electron-beam irradiation and beam switch off [Costantini, 2014b]. The following function can be used for least-squares fitting of the number of paramagnetic centres (N) versus time (t):…”