Persistent luminescence properties of monoclinic luminescent zirconium oxide annealed under different oxygen partial pressures

Abstract

Luminescent zirconium oxide (ZrO₂) with high purity (>3N) was annealed under different oxygen partial pressures (Po₂ = 10⁻¹⁴–10⁴ Pa) to investigate the effect of lattice defects on persistent luminescence (PersL). Although the Photoluminescence spectra profiles of samples (broad band emission centered at 485 nm) matched with the PersL spectra, PersL durations differed depending on the value of Po₂ during annealing. Samples annealed under a medium value of Po₂ such as 1 Pa tended to show long PersL duration. The two main trap levels were evaluated from thermoluminescence glow curves, and the ratio of two traps changed depending on the value of Po₂ during annealing. The time profiles of intensities of EPR signals (which assigned to F⁺-center and hole-trapped oxygen) were linked to the time profiles of luminescence intensities under and after ultraviolet irradiation. This result indicates that the F⁺-center and hole-trapped oxygen are involved in PersL.