Photochromic ceramics Ca2SnO4: Ho3+ with excellent reversible photoluminescence intensity modulation properties

Abstract

Inorganic photochromic (PC) materials with high light intensity modulation capability have great potential for applications in optical memory devices, optical switches, and fluorescent anticounterfeiting because of their favorable physical and chemical stability and simple synthesis. In this study, PC ceramics Ca2.02−xSnO4:xHo3+ are synthesized by a high-temperature solid-state reaction method and the microstructure and optical properties of the ceramics are analyzed. By studying their PC behavior, it is found that the coloring effect is best under 290 nm light irradiation, the ceramics change from light yellow to dark gray, and the original color of discolored ceramics basically restores after 10 min of 440 nm light irradiation. The original color can be completely recovered after heating to 623 K for 10 min. To study the reversible photoluminescence (PL) light intensity modulation performance of the material based on the PC behavior of ceramics, the maximum attenuation modulation ratio of 93.48% is detected at 550 nm after 6 min of 290 nm light irradiation, which is higher than most comparable PC ceramics. The recovery modulation ratio is 1164% after 8 min of 440 nm light irradiation. Using 290 nm light for coloring, followed by bleaching with 440 nm light or holding at 623 K for 10 min for 10 cycles, the ceramic light intensity modulation performance is almost unchanged and shows good reversibility. Finally, the mechanism behind the ceramic photochromic and reversible photoluminescence modulation is explained.