Synthesis and Study of Double NaYP2O7 Phosphates Doped with Rare-Earth Elements

Abstract

The synthesis of double phosphates of different composition NaY_1–xEu_xP₂O₇ and NaY_1–xTb_xP₂O₇ (х = 0, 0.025, 0.05, 0.075, 0.1) is technologically implemented by using a solution or extract of initial component in a rosin melt. The compounds are characterized by X-ray diffraction analysis and luminescence spectroscopy. The monoclinic NaYP₂O₇ polymorph structure is retained after doping with Eu³⁺ and Tb³⁺ ions. The NaY_1–xEu_xP₂O₇ luminescence excitation spectra (λ_em = 615 nm) contain the intense broad band from the charge transfer О^2– → Eu³⁺ at λ_max = 260 nm. In the NaY_1–xTb_xP₂O₇ luminescence excitation spectrum (λ_em = 545 nm), the most intense band at ~235 nm is produced by the transition 4f₈ → 4f  ⁷ 5d¹ in the Tb³⁺ ion. Double europium phosphates NaY_1–xEu_xP₂O₇ luminesce in the region of 550–750 nm under excitation at λ_ex = 260 nm, and the luminescence of phosphates NaY_1–xTb_xP₂O₇ occurs in the region of 530–565 nm at λ_ex = 235 nm. The highest integral luminescence intensity is demonstrated by NaY_0.95Eu_0.05P₂O₇ and NaY_0.95Tb_0.05P₂O₇.