Up-conversion phosphor Na2MoO4:Er3+/Yb3+for the optical temperature sensing and anti-counterfeiting

Lanthanide-based upconversion (UC) materials exhibit remarkable temperature-sensing properties as excited by near-infrared light. This article aims to investigate the UC emission and its temperature-sensing behavior of Na2MoO4:Er3+/Yb3+. The molybdate powder Na2MoO4:Er3+, Yb3+ shows bright green UC emission under a 980 nm laser. By monitoring the temperature-dependent green emission, the optical thermometric properties of Na2MoO4:xEr3+/0.01 Yb3+ are investigated. 1.38% K-1 is the maximum absolute sensitivity (SA) and the relative sensitivity (SR) is 1.21% K-1 with a 0.09-0.22 K temperature resolution (Delta T) at 0.001Er3+. The material was successfully combined with acrylic to prepare invisible anti-counterfeit patterns. These significant findings provide a theoretical foundation for temperature-sensing capabilities and potential applications in anti-counterfeiting measures.