Synthesis, optical spectroscopy and Judd-Ofelt analysis of Eu3+doped Li2BaP2O7 phosphors

A series of Li2BaP2O7: xEu3+ (x=0.1%, 1%, 3%, 5%) compound have been synthesized by the classic ceramic method. The obtained powders crystallize in the monoclinic system with C2/c space group. Excitation and emission spectra as well as luminescence decays were recorded. Five emission bands have been observed from the 5D0 excited state to the lower lying states 7F0, 7F1, 7F2, 7F3 and 7F4 at 578, 590, 615, 653 and 687 nm respectively upon exciting the sample with 375 nm wavelength. The Eu3+ Stark energy levels, the strength crystal field and the Calorimetric parameters of the Eu3+ ions in Li2BaP2O7 are calculated. A comparative study of the optical results obtained for the different Eu3+ concentrations was carried out by calculating the asymmetry ratio (1). The symmetry of the local environment of Eu3+ activators has been described in the frame of Judd-Ofelt (J-O) theory, using Ω2 and Ω4 intensity parameters derived from emission spectra. A comparison is made between these parameters in order to determine the type of connection between the Eu3+ activator ions and the Li2BaP2O7 host. The Judd-Ofelt parameters are used to calculate the relative transition probability, branching ratio and relative lifetime. The luminescence decay rates of 5D0 excited state is measured and the correspondent emission quantum efficiency is calculated. The effective bandwidth of the Eu3+ (∆λeff) and stimulated emission cross-section (σp) are also investigated.