Synthesis Design and Properties of Ca₅(BO₃)₃F: Bi³⁺/Eu³⁺: Insight into Luminescence, Temperature, and Pressure Sensing

Abstract

Nowadays, the utilization of noncontact temperature and pressure sensing is experiencing growing popularity. In this work, Bi 3+ , Eu 3+ -doped Ca 5 (BO 3 ) 3 F (CBOF) phosphors were synthesized via an ionic liquid-assisted electrospinning approach. The effect of molecular weight of polyvinylpyrrolidone on the morphology of CBOF was investigated, and a comprehensive analysis of its formation mechanism was presented. The luminescence properties of CBOF: Bi 3+ , Eu 3+ were studied systematically. The temperature-dependent emission of CBOF: Bi 3+ , Eu 3+ phosphor was discussed, and it displayed thermal sensitivity, which can be attributed to the distinct thermal response emission behaviors of Bi 3+ and Eu 3+ . The investigation of the pressure-dependent emission behavior of the CBOF: Bi 3+ phosphor revealed an anomalous phenomenon: with the increase of pressure, the emission peak showed a trend of first a blue shift and then a red shift. This anomaly was discussed in detail. The phosphor exhibits visual color change (blue to cyan), remarkable pressure sensitivity (4.76 nm/GPa), and a high upper pressure limit (24.2 GPa), indicating its potential use as an optical pressure sensor. Consequently, this study presents an innovative synthetic approach for fabricating CBOF, presenting a bifunctional material with promising prospects in the fields of temperature and pressure sensing.