LBGW:Nd3+phosphors for optical detection of temperature in dual biological windows with improved sensitivity

Identifier:  imarina:9464101

Handle: https://hdl.handle.net/20.500.11797/imarina9464101

Authors:  Douzi, Abir; Slimi, Sami; Madirov, Eduard; Serres, Josep Maria; Sole, Rosa Maria; Ben Salem, Ezzedine; Turshatov, Andrey; Richards, Bryce S; Mateos, Xavier

Abstract:
In this study, neodymium-doped Li3Ba2Gd3(WO4)8 (LBGW:x Nd3+) phosphors were synthesized via a conventional solid-state method and investigated for optical sensing of temperature. Upon near-infrared (NIR) excitation at 808 nm, three prominent infrared emission bands were observed, corresponding to the 4F3/2 -> 4I9/2, 4F5/2 -> 4I11/2, and 4F3/2 -> 4I11/2 transitions of Nd3+ ions, falling within the first and second biological windows (I-BW and II-BW), and thus enabling biologically compatible optical thermometry. Temperature-dependent fluorescence intensity ratio (FIR) analysis was carried out in the 303-473 K range using three emission band pairs derived from five emission lines: P1 and P2 from 4F3/2 -> 4I9/2, P3 from 4F5/2 -> 4I11/2 transition, and P4 and P5 from 4F3/2 -> 4I11/2. The three evaluated FIR schemes (P2/P1, P3/P1, and P5/P4) demonstrated distinct thermal responses, with FIR(P3/P1) exhibiting the highest relative sensitivity of 1.53 % K-1 and a thermal resolution of 8.86 x 10-5 K at 303 K. The phosphors also demonstrated excellent repeatability, photostability, and thermal reversibility over multiple heating-cooling cycles, confirming their robustness for non-contact, high-resolution temperature sensing. These results position LBGW:Nd3+ phosphors as a promising candidate for advanced optical thermometry, especially within I-BW and II-BW, where NIR emission enables compatibility with biomedical applications.