The effect of Eu 3+ and Gd 3+ co-doping on the morphology and luminescence of NaYF 4 :Eu 3+ , Gd 3+ phosphors

• Published in: New journal of chemistry 2021-06, Vol.45 (24), p.10599-10607
• Main Authors: Kolesnikov, Ilya E., Vidyakina, Aleksandra A., Vasileva, Marina S., Nosov, Viktor G., Bogachev, Nikita A., Sosnovsky, Vladimir B., Skripkin, Mikhail Y., Tumkin, Ilya I., Lähderanta, Erkki, Mereshchenko, Andrey S.
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D1NJ02193A

β-NaYF 4 :Eu 3+ microparticles co-doped with Gd 3+ ions were obtained by hydrothermal synthesis at 180 °C using citric acid as a stabilizing agent. All synthesized materials have a β-NaYF 4 crystalline phase, where the unit cell volume increases upon the addition of Eu 3+ and Gd 3+ ions. The particles have a hexagonal prism shape and a size of 40–714 nm, where Eu 3+ and Gd 3+ doping results in size reduction. Upon 393 nm excitation, phosphors exhibit distinct emission peaks centered at 591, 615, and 695 nm and a weak band at 650 nm attributed to 5 D 0 – 7 F J transitions ( J = 1–4). The optimum Eu 3+ doping concentration was found to be 30% in the NaYF 4 host. Concentration quenching was realized through dipole–dipole interactions. Kinetic measurements showed a gradual decline of the 5 D 0 lifetime from 6.7 ms to 2.2 ms along with an increase in Eu 3+ doping concentration. Co-doping of the small Gd 3+ number led to an increase of emission intensity and 5 D 0 lifetime. The effects of Eu 3+ doping and Gd 3+ co-doping on radiative and nonradiative decay rates were studied using 4f–4f intensity theory.