WEN Qiangqiang, BAO Jinxiao, WANG Lihe, BIAN Zhenhu, SUN Han, ZHANG Fenglong
(School of Materials and Metallurgy, Inner Mongolia University of Science and
Technology, Baotou 014017, Inner Mongolia, China)

Abstract: xNb₂O₅:Er-(1−x)₃YSZ colored ceramics with photochromic effect were prepared by using high temperature solid phase reaction method. Crystal structure, microstructure and optical properties of the samples were studied. It is found that the ceramic sample has a single phase crystal structure of Nb₂Zr₆O₁₇ with uniform and compact morphology at x=30 wt.%. Under the alternating treatment of 365 nm UV light and 350 ℃ heating, the ceramic surface showed obvious reversible color change, with the highest photochromic contrast reaching 22.6% and the fast response time to be close to 2 s. According to cyclic life test results, the ceramic samples showed high reversibility and good cyclic stability. Diffuse reflection spectroscopy and XPS test results indicated the presence of oxygen vacancy. The mechanism of oxygen vacancy capturing excited electrons to form color centers and releasing electrons under thermal perturbation dominates the photochromic process. Finally, a possible photochromic model was proposed to explain the mechanism of the photochromic process.
Key words: photochromic; Nb₂Zr₆O₁₇; reversibility; color centers