Synthetic design of Ca5(PO4)3F: Eu2+/3+for multi-functional applications in anti-counterfeiting, temperature and pressure sensing

Co-doping Eu2+/3+ in a single-phase phosphor is an efficient way to achieve emission color regulation, which possesses great prospective application prospects in anti-counterfeiting, optical temperature and optical pressure sensing. In this work, Eu2+/3+ co-doped Ca5(PO4)3F microspheres were successfully prepared by ionic liquidassisted electrospinning, and the morphologies changed from microspheres to microfibers by altering the viscosity of the solution. Furthermore, the formation mechanism of Ca5(PO4)3F: Eu2+/3+ was proposed. The luminescence properties of Ca5(PO4)3F: Eu2+/3+ samples were reported in detail, and emission behavior driven by excitation wavelength, temperature and pressure were revealed. Utilizing the excitation wavelength color development behavior of Ca5(PO4)3F: Eu2+/3+ phosphors, the films prepared with Ca5(PO4)3F: Eu2+/3+ and PVA displayed red or blue light at 254/365 nm. More importantly, the Ca5(PO4)3F: Eu2+/3+ phosphor exhibited temperature and pressure sensitivity, due to the distinct emission behaviors of Eu2+ and Eu3+ ions in response to changes of temperature and pressure. Notably, Ca5(PO4)3F: Eu2+/3+ phosphor exhibited remarkable pressure stability and sensitivity, with values of 84.6% and 24.98% GPa-1. Therefore, this multifunctional material possesses great potential applications in anti-counterfeiting and temperature as well as pressure sensing. In conclusion, this research furnishes a novel synthetic way for the preparation of fluorapatite, which holds significant importance in providing a relatively straightforward approach to combine these multi-functions in single-phase materials.