Fabrication and upconversion luminescence of novel transparent Er2O3 ceramics

Transparent Er2O3 ceramics were successfully fabricated via vacuum sintering for the first time, using low-temperature synthetic layered rare-earth hydroxide (LRH) as the precursor. The LRH exhibits single crystal structure and characteristic two-dimensional nanosheet morphology with a thickness of only similar to 10 nm. Calcining the LRH precursor at optimum temperature of 1000 degrees C yields a rounded fine oxide powder with an average particle size of similar to 35 nm and relatively uniform size distribution. With the sinterable oxide particle, the vacuum sintered Er2O3 ceramic has a relatively high transparency of 80 % at around 5.4 mu m (similar to 99 % of the theoretical value) and an average grain size of similar to 55 mu m. Under 980 nm laser excitation, the Er2O3 ceramic displays strong red emission at similar to 654-685 nm and weak green emission at similar to 553-565 nm arising from F-4(9/2)-> I-4(15/2) and (S3/2H11/2)-S-4-H-2 -> I-4(15/2) transitions, respectively. The intensities of red and green emissions rise along with increasing laser output powers, the upconversion mechanisms of which are both attributable to two-phonon processes. The CIE chromaticity diagrams move towards cooler tone from yellow to greenish-yellow colours with enhanced output powers. The lifetimes of the Er2O3 ceramic were determined to be similar to 13.0 and 8.4 mu s for the 684 and 565 nm emissions, respectively.