Fabrication and Characterization of Transparent (Y0.98−xTb0.02Eux)2O3 Ceramics with Color‐Tailorable Emission

Abstract

Transparent (Y0.98−xTb0.02Eux)2O3 (x = 0–0.04) ceramics with color‐tailorable emission have been successfully fabricated by vacuum sintering at the relatively low temperature of 1700°C for 4 h. These ceramics have the in‐line transmittances of ~73%–76% at 613 nm, the wavelength of Eu3+ emission (the 5D0→7F2 transition). Thermodynamic calculation indicates that the Tb4+ ions in the starting oxide powder can essentially be reduced to Tb3+ under ~10−3 Pa (the pressure for vacuum sintering) when the temperature is above ~394°C. The photoluminescence excitation (PLE) spectra of the transparent (Y0.98−xTb0.02Eux)2O3 ceramics exhibit one spin‐forbidden (high‐spin, HS) band at ~323 nm and two spin‐allowed (low‐spin, LS) bands at ~303 and 281 nm. Improved emissions were observed for both Eu3+ and Tb3+ by varying the excitation wavelength from 270 to 323 nm, without notably changing the color coordinates of the whole emission. The transparent (Y0.98Tb0.02)2O3 ceramic exhibits the typical green emission of Tb3+ at 544 nm (the 5D4→7F5 transition). With increasing Eu3+ incorporation, the emission color of the (Y0.98−xTb0.02Eux)2O3 ceramics can be precisely tailored from yellowish‐green to reddish‐orange via the effective energy transfer from Tb3+ to Eu3+ under the excitation with the peak wavelength of the HS band. At the maximum Eu3+ emission intensity (x = 0.02), the ceramic shows a high energy‐transfer efficiency of ~85.3%. The fluorescence lifetimes of both the 544 nm Tb3+ and 613 nm Eu3+ emissions were found to decrease with increasing Eu3+ concentration.