Luminescence Properties of Redispersible Tb³⁺‐Doped GdPO₄ Nanoparticles Prepared by an Ethylene Glycol Route

Abstract

Abstract Nanoparticles of Tb 3+ ‐doped GdPO 4 (Tb 3+ = 0, 2, 5, 7, 10, and 20 atom‐%) have been prepared at a relatively low temperature of 160 °C in ethylene glycol medium. The particles crystallize in a monoclinic structure with an average crystallite size of 30–50 nm. From the luminescence study of Tb 3+ ‐doped GdPO 4 , the magnetic dipole transition ( 5 D 4 → 7 F 5 ) at 545 nm (green) was found to be more prominent than the electric dipole transition ( 5 D 4 → 7 F 6 ) at 484 nm (blue). Maximum luminescence intensity and lifetime was observed for 7 atom‐% Tb 3+ . Above 7 atom‐% Tb 3+ , a decrease in luminescence was observed. This has been attributed to a concentration‐quenching effect due to the cross‐relaxation among Tb 3+ ions. The highest luminescence intensity of Tb 3+ was observed after excitation at 274 nm ( 8 S 7/2 → 6 I 11/2 of Gd 3+ ) among various excitation wavelengths (including f–f absorptions of Tb 3+ ). This is due to an efficient transfer of energy from Gd 3+ to Tb 3+ that shows GdPO 4 to be a potential host for Tb 3+ . These nanoparticles are found to be redispersible in water and ethanol and are incorporated into polyvinyl alcohol film homogeneously. This film showed bright green emission.