Study on the properties of boromullite-type luminescent material Al18B4O33: Cr3+

Abstract

In this paper, the high-temperature solid-phase method was used to synthesise Al₁₈B₄O₃₃: Cr³⁺ luminescent materials with a rod-like structure of about 2 μm. In addition, Cr³⁺ ions occupy the Al³⁺ site in the main body of the Al₁₈B₄O₃₃ host. Investigating its luminescence properties, it is found that under 384 nm excitation, Al₁₈B₄O₃₃: Cr³⁺ produces broadband emission located at 712 nm belonging to the ⁴T₂→⁴A₂ transition of Cr³⁺. The best luminescence intensity was achieved when the Cr³⁺ doping concentration was 0.015 mol. And the quantum efficiency reaches 62.6 %. The relationship between the luminescence intensity of excitation and emission spectra as a function of concentration and suggests that the mechanism of concentration quenching of Cr³⁺ in Al₁₈B₄O₃₃ is caused by non-radiative energy transfer among the nearest-neighbor ions. Through the analysis of thermal stability spectrum, it was found that the luminescence intensity could be achieved up to 65.2 % of the room temperature at 423 K, showing good thermal stability. Testing the water stability of Al₁₈B₄O₃₃: Cr³⁺ showed that the luminescence intensity decreased to 61.8 % of the initial intensity after 5 h of immersion. The results suggest that Al₁₈B₄O₃₃: Cr³⁺ provides a new direction for the prospects of NIR development.