Photo-quenched luminescence in Co(II)-doped sol–gel zirconia

Abstract

The quenching process of the laser-induced luminescence of Co(II)-doped zirconia samples prepared by the sol–gel method is reported. Zirconia monoliths doped with Co(II) at different concentrations, were laser irradiated producing fluorescence; its intensity, measured by the slope at the low energy side of the Raman spectra, is reduced with the irradiation time. The rate the fluorescence decays can be modeled as a double exponential function of the irradiation time; the characteristic times involved in this quenching process are in the range of seconds. The suppression of the luminescence has been associated to the local heating produced when the laser beam is focused in a small area (≈2 microns in diameter) on the sample. This heating process reduces physical (such as grain boundaries and surface states) and chemical (oxygen vacancies) defects; however, some residual fluorescence still remains after long periods of illumination.