Synthesis and optical properties of Ce_1-x-yEu_xPr_yO_2-δ solid solution

Abstract

Eu- and Pr-doped ceria, Ce_1-x-yEu_xPr_yO_2-δ (where x=0, 0.05, and 0.01, y=0, 0.0005, and 0.05) powder samples were synthesized by a coprecipitation method followed by heat treatment at 600°C for 3 h in air. The samples were characterized by XRD, color measurement, and UV-Vis diffuse reflectance spectroscopy. X-ray diffraction data indicated the formation of Ce_1-x-yEu_xPr_yO_2-δ solid solution with fluorite-type structure. The powders of Ce_1-yPr_yO_2-δ (y=0, 0.0005, and 0.05) turn to dark brown color with increasing Pr content, where samples in a smaller amount of Pr content can get high brightness near yellow-brown. It was found that Eu- and Pr-codoped ceria samples，Ce_0.9945Eu_0.005　Pr_0.0005O_2-δ and Ce_0.9895Eu_0.01Pr_0.0005O_2-δ，exhibited change of time-dependent color behavior. The UV-vis versus time measurement showed clear photochromic properties depending on absorption due to Eu³⁺-Pr³⁺ center in CeO₂.