Luminescence and temperature sensing abilities of zincate phosphors co-doped bismuth Bi3+ and lanthanide Eu3+/Sm3+

Abstract We proposed the FIR-based method involving dual luminescent centers of Bi3+ and lanthanide (Ln): Eu3+/Sm3+. The tunable color region changing from cyan to jacinth with the augment of Eu3+/Bi3+ ratio resulted from the f-f characteristics transition of Eu3+. Owing to Bi3+ being susceptive to crystal surroundings, and asymmetric crystal sites of Sm3+ in the host, phenomena respectively involving redshift and energy level splitting occur. In addition, benefiting from the unshielded 3d orbitals, the thermal quenching of Bi3+ ion occurs through energy-level crossing relaxation (ELCR), while the heating quenching of Ln3+ ions takes place due to the shielded 4f orbitals via multi-phonon deexcitation (MPD). Considering the symmetric crystal environment, stronger sensitivity compared with Sm3+ ion to the outer environment due to its smaller value of thermal activation energy and the weaker crystal field than CAZO:Bi3+,Sm3+, an excellent temperature sensing sensitivity is excepted by applying Eu3+ as the temperature-detecting signal.