Multi-color tunable luminescence of SrMoO4: Tb3+, Eu3+ nanophosphors for dual-mode temperature monitoring and multi-dimensional high secure anti-counterfeiting

New lanthanide-doped nanoparticles with unique optical characterisics are highly desirable for non-contact thermal sensing and advanced optical anticounterfeiting. The fluorescence intensity ratio (FIR) nanothermometers with higher relative temperature sensitivity (Sr) offer several advantages over traditional contact-based temperature sensors, including high sensitivity, fast response times, and non-invasive measurement. Herein, we describe the synthesis of nanocrystalline SrMoO4:RE3+ (RE3+= Tb3+ and Eu3+) using co-precipitation method for various optical applications, such as temperature sensing and anti-counterfeiting. These phosphors nanoparticle emit multi-colors by varying the percentage of Eu3+ and Tb3+ ions incorporated into SrMoO4. The maximum absolute sensitivity for multi-mode non-contact temperature measurement based on FIR and the distinct thermal behaviour of Eu3+ and Tb3+ ions was reached at 0.055 K-1. The maximum relative sensitivity is reached at 1.8 % K–1, with a minimum temperature resolution δT of 0.043 K at 300 K and maximum δT of 0.272 K. The developed nanophosphors emit green light when it doped Tb3+ and emit red light when it doped with Eu3+, and both demonstrate distinct changes in their response to temperature variations. The color change with temperature elucidates a real base for potential application in advanced anti-counterfeiting. The co-precipitation method we used to synthesize the nanophosphors is easy to scale up for industrial applications. So, the developed nanophosphors with multicolor emissions is of scientific and technological relevence.