Luminescence properties of Eu 3+ ions in K 2YF 5 crystals

Abstract

Luminescence properties of Eu 3+ ions (0.1, 1.0 and 6.0 mol%) in K 2YF 5 crystals are investigated by the site-selective laser-excitation spectroscopy. The excitation spectrum of the 5D 0 emission exhibits two strong 7F 0 → 5D 0 excitation lines together with four weaker lines. Six different emission spectra are obtained under the excitation at each excitation line indicating that there existed at least six different sites for Eu 3+. The relative intensity of the excitation lines is dependent on the Eu 3+ concentrations. The 5D 0 emissions of Eu 3+ show two types of decay behavior with lifetimes of 0.5 and 5.0 ms at 15 K. It is suggested that the fast and slow decays correspond to isolated and paired Eu 3+ ions in K 2YF 5. The results are discussed in relation with one dimensional chain structure of the K 2YF 5 lattice.