Synthesis and Luminescent Properties of Europium(III, II) Phosphates

Abstract

Nanosized europium phosphates Eu₃PO₇, Eu(PO₃)₃, and Eu(PO₃)₃: Eu²⁺ have been prepared by low-temperature extraction-pyrolytic method. Optimal temperature and time of precursor pyrolysis for preparing luminophor containing europium in different oxidation states have been determined. Phosphate luminophore based on Eu³⁺ exhibit intense red luminescence with λ_max ∼ 600–650 nm. Luminescence spectra of Eu(PO₃)₃: Eu²⁺ are characterized by emission bands in the region 400–700 nm typical for both Eu³⁺ (the bands of ⁵D₀–⁷F_j(j = 0, 1, 2) transitions), and Eu²⁺ (the band of 4f⁶5d → ⁸S_7/2 transition). Luminescence-exciting wavelengths provide different contribution to the radiation intensity of both Eu²⁺ and Eu³⁺.