Enhanced Phase Stability and Photoluminescence of Eu3+ Modified t-ZrO2 Nanoparticles

Abstract

Tetragonal (t) ZrO2 nanoparticles have been obtained by a partial Eu3+→Zr4+ substitution, synthesized using a simple oxalate method at a moderate temperature of 650°C in air. The Eu3+ additive, 2 mol% used according to the optimal photoluminescence (PL), gives small crystallites of the sample. On raising the temperature further, the average crystallite size D grows slowly from 16 nm to a value as big as 49 nm at 1200°C. The Eu3+:t-ZrO2 nanoparticles have a wide PL spectrum at room temperature in the visible to near-IR regions (550–730 nm) in the 5D0→7FJ (Eu3+), J=1–4, electronic transitions. The intensity of the 5D0→7F4 group is as large as that of the characteristic 5D0→7F2 group of the spectrum in the forced electric-dipole allowed transitions. The enhanced t-ZrO2 phase stability and wide PL can be attributed to the combined effects of an amorphous Eu3+-rich surface and part of the Eu3+ doping of ZrO2 of small crystallites.