Luminescent properties of europium-activated yttrium gadolinium phosphates

Abstract

Nanocrystalline Y1 − x − y Gd x Eu y PO4 phosphors have been prepared via precipitation from aqueous solutions. From their luminescence and excitation spectra, the intensity ratio I 615/I 594 of the Eu3+ luminescence bands corresponding to electric dipole and magnetic dipole transitions has been determined as a function of Gd3+ content. The critical concentration and effective energy transfer radius in Y1 − x − y Gd x Eu y PO4 have been evaluated. Excitation of Gd3+8 S J −6 D J and 8 S J −6 J J transitions to Eu3+ luminescence excitation levels in Y0.99 − x Gd x Eu0.01PO4 involves efficient energy transfer. Under 250-nm excitation, the Eu3+ luminescence yield in Y0.99 − x Gd x Eu0.01PO4 is a factor of 2.5–3 higher than that in Y0.99Eu0.01PO4.