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

Abstract

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 liquid-assisted 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.